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Thapa B, Bell DS, Anderson JL. Extraction of volatile organic compounds liberated upon filament extrusion by 3D pen and its comparison with a desktop 3D printer using solid-phase microextraction fiber and Arrow. J Chromatogr A 2024; 1719:464740. [PMID: 38401373 DOI: 10.1016/j.chroma.2024.464740] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2023] [Revised: 02/12/2024] [Accepted: 02/13/2024] [Indexed: 02/26/2024]
Abstract
Desktop 3D printers that operate by the fused deposition modeling (FDM) mechanism are known to release numerous hazardous volatile organic compounds (VOCs) during printing, including some with potential carcinogenic effects. Operating in a similar manner to FDM 3D printers, 3D pens have gained popularity recently from their ability to allow users to effortlessly draw in the air or create various 3D printed shapes while handling the device like a pen. In contrast to numerous modern 3D printers, 3D pens lack their own ventilation systems and are often used in settings with minimum airflow. Their operation makes users more vulnerable to VOC emissions, as the released VOCs are likely to be in the breathing zone. Consequently, monitoring VOCs released during the use of 3D pens is crucial. In this study, VOCs liberated while extruding acrylonitrile butadiene styrene (ABS) filaments from a 3D pen were measured by solid-phase microextraction (SPME) combined with gas chromatography/mass spectrometry (GC/MS). SPME was investigated using the traditional fiber and Arrow geometries with the DVB/Carbon WR/PDMS sorbent while four different brands of ABS filaments-Amazon Basics, Gizmodork, Mynt 3D, and Novamaker-were used with the 3D pen. Heatmap analysis showed differentiation among these brands based on the liberated VOCs. The nozzle temperature and printing speed were found to affect the number and amount of released VOCs. This study goes a step further and presents for the first time a comparison between 3D pen and a desktop 3D printer based on liberated VOCs. Interestingly, the findings reveal that the 3D pen releases a greater number and amount of VOCs compared to the printer. The amounts of liberated VOCs, as indicated by the corresponding chromatographic peak areas, were found to be 1.4 to 62.6 times higher for the 3D pen compared to the 3D printer when using SPME Arrow.
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Affiliation(s)
- Bhawana Thapa
- Department of Chemistry, Iowa State University, Ames, IA 50011, USA
| | - David S Bell
- Restek Corporation, 110 Benner Circle, Bellefonte, PA 16823, USA
| | - Jared L Anderson
- Department of Chemistry, Iowa State University, Ames, IA 50011, USA.
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2
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Zeger VR, Bell DS, Anderson JL. Polymeric ionic liquid sorbent coatings in thin film microextraction: Insight into sorbent selectivity for pesticides and cannabinoids. J Chromatogr A 2024; 1715:464583. [PMID: 38160584 DOI: 10.1016/j.chroma.2023.464583] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 12/06/2023] [Accepted: 12/14/2023] [Indexed: 01/03/2024]
Abstract
Polymeric ionic liquid (PIL) sorbent coatings consisting of polymerizable cations and anions were employed as sorbent coatings in thin film microextraction (TFME) for the extraction of pesticides and cannabinoids. The blades consisted of a thin film of PIL sorbents chemically bonded to vinyltrimethoxysilane-functionalized nitinol sheets. The imidazolium- or ammonium-based PIL sorbents contained aromatic benzyl moieties as well as polar hydroxyl groups or aliphatic functional groups within the chemical structure of the IL monomer. The chemical structure of the IL crosslinkers of the PILs were kept constant across each sorbent, except for the anion, which consisted of either bis[(trifluoromethyl)sulfonyl]imide ([NTf2-]), p-styrenesulfonate ([SS-]), or 3-sulfopropyl acrylate ([SPA-]). Temperature, salt content, and methanol content were optimized as extraction conditions to maximize pesticide-cannabinoid selectivity using Doehlert design of experiments (DOE). Effects of these three factors on selectivity and extraction efficiency are discussed. The optimal extraction conditions consisting of sample temperature (31°C), sodium chloride (30% w/v), and methanol content (0.25% v/v) are compared to initial sorbent screening conditions at a sample temperature of 40°C, 15% (w/v) sodium chloride, and 2.5% (v/v) methanol content. PIL sorbent swelling behavior at different salt and methanol content conditions and its effect on extraction efficiency are hypothesized. Selectivity factors for the sorbents indicated that aromatic moieties within the IL monomer may enhance pesticide-cannabinoid selectivity under optimized conditions, but the extraction efficiency of pesticides that are known to coelute with cannabinoids in the chromatographic separation may be enhanced by employing sorbent coatings with [SPA-] anions.
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Affiliation(s)
- Victoria R Zeger
- Department of Chemistry, Iowa State University, 1605 Gilman Hall, Ames, IA 50011, USA
| | - David S Bell
- Restek Corporation, 110 Benner Circle, Bellefonte, Pennsylvania 16823, USA
| | - Jared L Anderson
- Department of Chemistry, Iowa State University, 1605 Gilman Hall, Ames, IA 50011, USA.
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3
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Moeini B, Pinder JW, Avval TG, Jacobsen C, Brongersma HH, Průša S, Bábík P, Vaníčková E, Argyle MD, Strohmeier BR, Jones B, Shollenberger D, Bell DS, Linford MR. Controlling the surface silanol density in capillary columns and planar silicon via the self-limiting, gas-phase deposition of tris(dimethylamino)methylsilane, and quantification of surface silanols after silanization by low energy ion scattering. J Chromatogr A 2023; 1707:464248. [PMID: 37598532 DOI: 10.1016/j.chroma.2023.464248] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2023] [Revised: 07/25/2023] [Accepted: 07/27/2023] [Indexed: 08/22/2023]
Abstract
Surface silanols (Si-OH) play a vital role on fused silica surfaces in chromatography. Here, we used an atmospheric-pressure, gas-phase reactor to modify the inner surface of a gas chromatography, fused silica capillary column (0.53 mm ID) with a small, reactive silane (tris(dimethylamino)methylsilane, TDMAMS). The deposition of TDMAMS on planar witness samples around the capillary was confirmed with X-ray photoelectron spectroscopy (XPS), ex situ spectroscopic ellipsometry (SE), and wetting. The number of surface silanols on unmodified and TDMAMS-modified native oxide-terminated silicon were quantified by tagging with dimethylzinc (DMZ) via atomic layer deposition (ALD) and counting the resulting zinc atoms with high sensitivity-low energy ion scattering (HS-LEIS). A bare, clean native oxide - terminated silicon wafer has 3.66 OH/nm2, which agrees with density functional theory (DFT) calculations from the literature. After TDMAMS modification of native oxide-terminated silicon, the number of surface silanols decreases by a factor of ca. 10 (to 0.31 OH/nm2). Intermediate surface testing (IST) was used to characterize the surface activities of functionalized capillaries. It suggested a significant deactivation/passivation of the capillary with some surface silanols remaining; the modified capillary shows significant deactivation compared to the native/unmodified fused silica tubing. We believe that this methodology for determining the number of residual silanols on silanized fused silica will be enabling for chromatography.
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Affiliation(s)
- Behnam Moeini
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602, USA
| | - Joshua W Pinder
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602, USA
| | - Tahereh G Avval
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602, USA
| | - Collin Jacobsen
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602, USA
| | - Hidde H Brongersma
- Department of Applied Physics, Eindhoven University of Technology, 5600 MB Eindhoven, the Netherlands
| | - Stanislav Průša
- Institute of Physical Engineering, Brno University of Technology, Technická 2, Brno 616 69, Czech Republic; CEITEC BUT, Brno University of Technology, Purkyňova 123, 612 00 Brno, Czech Republic
| | - Pavel Bábík
- Institute of Physical Engineering, Brno University of Technology, Technická 2, Brno 616 69, Czech Republic; CEITEC BUT, Brno University of Technology, Purkyňova 123, 612 00 Brno, Czech Republic
| | - Elena Vaníčková
- Institute of Physical Engineering, Brno University of Technology, Technická 2, Brno 616 69, Czech Republic; CEITEC BUT, Brno University of Technology, Purkyňova 123, 612 00 Brno, Czech Republic
| | - Morris D Argyle
- Department of Chemical Engineering, Brigham Young University, Provo, UT 84602, USA
| | - Brian R Strohmeier
- Materials Group, Avery Dennison Corp., 8080 Norton Parkway, Mentor, OH 44060, USA
| | - Brian Jones
- Restek Corporation, 110 Benner Circle, Bellefonte, PA 16823, USA
| | | | - David S Bell
- Restek Corporation, 110 Benner Circle, Bellefonte, PA 16823, USA
| | - Matthew R Linford
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602, USA.
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Zeger VR, Bell DS, Anderson JL. Understanding the influence of polymeric ionic liquid sorbent coating substituents on cannabinoid and pesticide affinity in solid-phase microextraction. J Chromatogr A 2023; 1706:464222. [PMID: 37523907 DOI: 10.1016/j.chroma.2023.464222] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Revised: 07/04/2023] [Accepted: 07/18/2023] [Indexed: 08/02/2023]
Abstract
To understand factors that drive pesticide-cannabinoid selectivity in solid-phase microextraction (SPME), eight new polymeric ionic liquid (PIL) sorbent coatings were designed and compared to four previously reported PIL sorbent coatings for the extraction of pesticides. The four PIL sorbent coatings consisted of either vinylimidazolium or vinylbenzylimidazolium ILs with long alkyl chain substituents (i.e., -C8H17 or -C12H25) and bis[(trifluoromethyl)sulfonyl]imide ([NTf2-]) anions, from which the eight new PIL sorbent coatings were adapted. Modifications to the chemical structure of IL monomers and crosslinkers included incorporation of polymerizable p-styrenesulfonate or 3-sulfopropyl acrylate anions, the addition of aromatic moieties, and/or the addition of polar functional groups (i.e., -OH or -O- groups). A total of ten commonly regulated pesticides and six cannabinoids were examined in this study. The effect of salt on the solubility of pesticides and cannabinoids in aqueous solutions was assessed by determining their extraction efficiencies in the presence of varied methanol content. Differences in their solubilities appear to play a dominant role in enhancing pesticide-cannabinoid selectivity. The selectivity, represented as the ratio of pesticide total peak areas to cannabinoid total peak areas, also exhibited a moderate correlation to the affinity of the sorbent coatings towards both the pesticides and the cannabinoids. A positive correlation was observed for the pesticides and a negative correlation was observed for the cannabinoids, suggesting that selectivity was driven by more than the presence of salt in the samples. The sorbent coatings' affinity towards each class of analytes were examined to determine specific interactions that might influence selectivity. The two main structural modifications increasing pesticide-cannabinoid selectivity included the absence of aromatic moieties and the addition of hydrogen bond donor functional groups. Extractions of simple aromatic molecules as probes were performed under similar extraction conditions as the cannabinoids and confirmed the influence of hydrogen bonding interactions on sorbent coating affinity.
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Affiliation(s)
- Victoria R Zeger
- Department of Chemistry, Iowa State University, Ames, IA 50011, United States
| | - David S Bell
- Restek Corporation, 110 Benner Circle, Bellefonte, Pennsylvania 16823, United States
| | - Jared L Anderson
- Department of Chemistry, Iowa State University, Ames, IA 50011, United States.
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Moeini B, Avval TG, Brongersma HH, Průša S, Bábík P, Vaníčková E, Strohmeier BR, Bell DS, Eggett D, George SM, Linford MR. Area-Selective Atomic Layer Deposition of ZnO on Si\SiO 2 Modified with Tris(dimethylamino)methylsilane. Materials (Basel) 2023; 16:4688. [PMID: 37445002 DOI: 10.3390/ma16134688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2023] [Revised: 06/19/2023] [Accepted: 06/25/2023] [Indexed: 07/15/2023]
Abstract
Delayed atomic layer deposition (ALD) of ZnO, i.e., area selective (AS)-ALD, was successfully achieved on silicon wafers (Si\SiO2) terminated with tris(dimethylamino)methylsilane (TDMAMS). This resist molecule was deposited in a home-built, near-atmospheric pressure, flow-through, gas-phase reactor. TDMAMS had previously been shown to react with Si\SiO2 in a single cycle/reaction and to drastically reduce the number of silanols that remain at the surface. ZnO was deposited in a commercial ALD system using dimethylzinc (DMZ) as the zinc precursor and H2O as the coreactant. Deposition of TDMAMS was confirmed by spectroscopic ellipsometry (SE), X-ray photoelectron spectroscopy (XPS), and wetting. ALD of ZnO, including its selectivity on TDMAMS-terminated Si\SiO2 (Si\SiO2\TDMAMS), was confirmed by in situ multi-wavelength ellipsometry, ex situ SE, XPS, and/or high-sensitivity/low-energy ion scattering (HS-LEIS). The thermal stability of the TDMAMS resist layer, which is an important parameter for AS-ALD, was investigated by heating Si\SiO2\TDMAMS in air and nitrogen at 330 °C. ALD of ZnO takes place more readily on Si\SiO2\TDMAMS heated in the air than in N2, suggesting greater damage to the surface heated in the air. To better understand the in situ ALD of ZnO on Si\SiO2\TDMAMS and modified (thermally stressed) forms of it, the ellipsometry results were plotted as the normalized growth per cycle. Even one short pulse of TDMAMS effectively passivates Si\SiO2. TDMAMS can be a useful, small-molecule inhibitor of ALD of ZnO on Si\SiO2 surfaces.
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Affiliation(s)
- Behnam Moeini
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602, USA
| | - Tahereh G Avval
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602, USA
| | - Hidde H Brongersma
- Department of Applied Physics, Eindhoven University of Technology, 5600 MB Eindhoven, The Netherlands
| | - Stanislav Průša
- Institute of Physical Engineering, Brno University of Technology, Technická 2, 616 69 Brno, Czech Republic
- CEITEC BUT, Brno University of Technology, Purkyňova 123, 612 00 Brno, Czech Republic
| | - Pavel Bábík
- Institute of Physical Engineering, Brno University of Technology, Technická 2, 616 69 Brno, Czech Republic
- CEITEC BUT, Brno University of Technology, Purkyňova 123, 612 00 Brno, Czech Republic
| | - Elena Vaníčková
- Institute of Physical Engineering, Brno University of Technology, Technická 2, 616 69 Brno, Czech Republic
- CEITEC BUT, Brno University of Technology, Purkyňova 123, 612 00 Brno, Czech Republic
| | - Brian R Strohmeier
- Materials Group-NA, Avery Dennison Corporation, 8080 Norton Parkway, Mentor, OH 44060, USA
| | - David S Bell
- Restek Corporation, 110 Benner Circle, Bellefonte, PA 16823, USA
| | - Dennis Eggett
- Department of Statistics, Brigham Young University, Provo, UT 84602, USA
| | - Steven M George
- Department of Chemistry, University of Colorado, 215 UCB, Boulder, CO 80309, USA
| | - Matthew R Linford
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602, USA
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6
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Thapa B, Hsieh SA, Bell DS, Anderson JL. Monitoring the liberation of volatile organic compounds during fused deposition modeling three dimensional printing using solid-phase microextraction coupled to gas chromatography/mass spectrometry. J Chromatogr A 2023; 1693:463886. [PMID: 36870231 DOI: 10.1016/j.chroma.2023.463886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 02/14/2023] [Accepted: 02/18/2023] [Indexed: 02/23/2023]
Abstract
Three-dimensional (3D) printers have gained tremendous popularity and are being widely used in offices, laboratories, and private homes. Fused deposition modeling (FDM) is among the most commonly used mechanisms by desktop 3D printers in indoor settings and relies on the extrusion and deposition of heated thermoplastic filaments, resulting in the liberation of volatile organic compounds (VOCs). With the growing use of 3D printers, concerns regarding human health have risen as the exposure to VOCs may cause adverse health effects. Therefore, it is important to monitor VOC liberation during printing and to correlate it to filament composition. In this study, VOCs liberated with a desktop printer were measured by solid-phase microextraction (SPME) combined with gas chromatography/mass spectrometry (GC/MS). SPME fibers featuring sorbent coatings of varied polarity were chosen for the extraction of VOCs liberated from acrylonitrile butadiene styrene (ABS), tough polylactic acid, and copolyester+ (CPE+) filaments. It was found that for all three filaments tested, longer print times resulted in a greater number of extracted VOCs. The ABS filament liberated the most VOCs while the CPE+ filaments liberated the fewest VOCs. Through the use of hierarchical cluster analysis and principal component analysis, filaments as well as fibers could be differentiated based on the liberated VOCs. This study demonstrates that SPME is a promising tool to sample and extract VOCs liberated during 3D printing under non-equilibrium conditions and can be used to aid in tentative identification of the VOCs when coupled to gas chromatography-mass spectrometry.
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Affiliation(s)
- Bhawana Thapa
- Department of Chemistry, Iowa State University, Ames, Iowa 50011 USA
| | - Shu-An Hsieh
- Department of Chemistry, Iowa State University, Ames, Iowa 50011 USA
| | - David S Bell
- Restek Corporation, 110 Benner Circle, Bellefonte, Pennsylvania 16823, USA
| | - Jared L Anderson
- Department of Chemistry, Iowa State University, Ames, Iowa 50011 USA.
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Emmons RV, Karaj E, Cudjoe E, Bell DS, Tillekeratne LV, Gionfriddo E. Leveraging multi-mode microextraction and liquid chromatography stationary phases for quantitative analysis of neurotoxin β-N-methylamino-L-alanine and other non-proteinogenic amino acids. J Chromatogr A 2022; 1685:463636. [DOI: 10.1016/j.chroma.2022.463636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Revised: 10/15/2022] [Accepted: 11/02/2022] [Indexed: 11/09/2022]
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Muraco CE, Bell DS. Highlights from the 50th International Symposium on High Performance Liquid Phase Separations and Related Techniques (HPLC 2022). LCGC N Am 2022. [DOI: 10.56530/lcgc.na.ws5783s4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
Abstract
After three “lost” years, the 50th International Symposium on High Performance Liquid Phase Separations and Related Techniques, or HPLC 2022, returned. The symposium was held at the Town and Country Hotel and Conference Center in sunny San Diego, California, from June 18–23, 2022. The HPLC symposium continues to be the premier event bringing together leading scientists in the field of liquid chromatography (LC) and related techniques. The conference was chaired by Frantisek Svec of Charles University, and, especially under the uncertain times leading up to the event, was very successful and welcomed by the attendees.
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Patel DI, Major GH, Jacobsen C, Shah D, Strohmeier BR, Shollenberger D, Bell DS, Argyle MD, Linford MR. Flow-Through Atmospheric Pressure-Atomic Layer Deposition Reactor for Thin-Film Deposition in Capillary Columns. Anal Chem 2022; 94:7483-7491. [PMID: 35579626 DOI: 10.1021/acs.analchem.1c05029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We demonstrate the development of a new atmospheric pressure-atomic layer deposition(AP-ALD) system to coat the inner walls of capillary columns for gas chromatography (GC). Unlike traditional ALD, this reactor operates at near-atmospheric pressure and addresses the challenges of depositing thin films inside capillaries, which include long pump down times, deposition in high-aspect-ratio materials, and temperature control. We show ALD of alumina in 5 and 12 m capillaries (0.53 mm ID) via sequential half reactions of trimethylaluminum and water. Our system yields pinhole-free, uniform thin films. It includes small witness chambers for witness silicon shards before and after the capillary. An engineering flow/transport analysis of the device is provided. Our ALD alumina thin films are characterized by spectroscopic ellipsometry (SE), X-ray photoelectron spectroscopy, transmission electron microscopy (TEM), and energy-dispersive X-ray spectroscopy. Alumina film growth achieved is 1.4-1.5 Å/cycle, which is consistent with previously reported results. Film thickness measurements by SE on witness shards of silicon and by TEM at both ends of the capillary are in good agreement. A capillary column coated with alumina is used to separate different gases by GC, although the retention times of gases are essentially the same as with an untreated fused silica capillary. This successful deposition of ALD alumina in long capillaries opens the door for other possible ALD coatings, including hybrid organic-inorganic coatings, using the 450+ ALD precursors available today.
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Affiliation(s)
- Dhananjay I Patel
- Department of Chemistry & Biochemistry, Brigham Young University, Provo, Utah 84602, United States
| | - George H Major
- Department of Chemistry & Biochemistry, Brigham Young University, Provo, Utah 84602, United States
| | - Collin Jacobsen
- Department of Chemistry & Biochemistry, Brigham Young University, Provo, Utah 84602, United States
| | - Dhruv Shah
- Department of Chemistry & Biochemistry, Brigham Young University, Provo, Utah 84602, United States
| | - Brian R Strohmeier
- Label and Graphic Materials, Avery Dennison Corporation, North America, 8080 Norton Parkway, Mentor, Ohio 44060, United States
| | - Daniel Shollenberger
- Restek Corporation, 110 Benner Circle, Bellefonte, Pennsylvania 16823, United States
| | - David S Bell
- Restek Corporation, 110 Benner Circle, Bellefonte, Pennsylvania 16823, United States
| | - Morris D Argyle
- Department of Chemical Engineering, Brigham Young University, Provo, Utah 84602, United States
| | - Matthew R Linford
- Department of Chemistry & Biochemistry, Brigham Young University, Provo, Utah 84602, United States
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Bell DS. New Liquid Chromatography Columns and Accessories in 2022. LCGC N Am 2022. [DOI: 10.56530/lcgc.na.sx2967r4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
This article covers liquid chromatography (LC) columns and accessories commercially released after Pittcon 2021 through this year’s virtual conference. Like in the past, LCGC sent out a survey in late 2021 and early 2022 asking vendors to supply information on products launched over the past year. Note that new products for gas chromatography (GC), LC instrumentation and software, and sample preparation are covered elsewhere. The information for this article was obtained over several months; therefore, it is possible that some information was missed or misinterpreted. The reader is encouraged to check with specific vendor sites for additional products as well as more detailed information on product usage and attributes. Links to vendor sites are provided where applicable.
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11
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Bell DS. The Current Status of Metal-Organic Frameworks (MOFs) for Use in Liquid Chromatography. LCGC N Am 2022. [DOI: 10.56530/lcgc.na.kt3688w6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Metal-organic frameworks (MOFs) are self-assembled combinations of metals and inorganic ligands that result in a relatively young class of highly ordered, porous materials. Because of the number of structural and chemical possibilities, high surface area, controlled pore volume, and favorable thermal properties, MOFs are being investigated in several fields, including chromatography. Because of the enormous interest in a 2018 “Column Watch” article on the subject and the high level of research in the field, this article explores recent (2019–present) activity specifically toward the application of MOFs for liquid chromatography (LC).
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12
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Patel DI, Roychowdhury T, Shah D, Jacobsen C, Herrington JS, Hoisington J, Myers C, Salazar BG, Walker AV, Bell DS, Linford MR. 6-Phenylhexyl silane derivatized, sputtered silicon solid phase microextraction fiber for the parts-per-trillion detection of polyaromatic hydrocarbons in water and baby formula. J Sep Sci 2021; 44:2824-2836. [PMID: 33989452 DOI: 10.1002/jssc.202100266] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 05/11/2021] [Accepted: 05/12/2021] [Indexed: 12/23/2022]
Abstract
We report the fabrication of 6-phenylhexylsilane derivatized, sputtered silicon, solid phase microextraction fibers that show parts per trillion detection limits for polyaromatic hydrocarbons, and negligible carry over and phase bleed. Their fabrication involves sputtering silicon on silica fibers under various conditions. Six different fibers were evaluated by generating three different thicknesses of sputtered silicon at two different throw distances, which altered the morphologies of the silicon surfaces. All of the fibers were coated with similar thicknesses of 6-phenylhexylsilane (ca. 2 nm). These fibers were characterized with multiple analytical techniques. The optimum fiber configuration was then used to analyze polyaromatic hydrocarbons via direct immersion, gas chromatography mass spectrometry. Our best fiber for the extraction of low molecular weight polyaromatic hydrocarbons in water had similar performance to that of a commercial fiber. However, our fiber demonstrated ca. 3 times the extraction efficiency for higher molecular weight polyaromatic hydrocarbons. In addition, it outperformed the commercial fiber by showing better linearity, repeatability, and detection limits. A method for analyzing polyaromatic hydrocarbons in baby formula was developed, which showed very good linearity (0.5-125 ppb), repeatability (2-26%), detection limits (0.12-0.81 ppb), and recoveries (103-135%). In addition, our fiber showed much less (negligible) carry over and phase bleed than the commercially available fibers.
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Affiliation(s)
- Dhananjay I Patel
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah, 84602, USA
| | - Tuhin Roychowdhury
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah, 84602, USA
| | - Dhruv Shah
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah, 84602, USA
| | - Collin Jacobsen
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah, 84602, USA
| | - Jason S Herrington
- Restek Corporation, 110 Benner Circle, Bellefonte, Pennsylvania, 16823, USA
| | - Jason Hoisington
- Restek Corporation, 110 Benner Circle, Bellefonte, Pennsylvania, 16823, USA
| | - Colton Myers
- Restek Corporation, 110 Benner Circle, Bellefonte, Pennsylvania, 16823, USA
| | - Bryan G Salazar
- Department of Chemistry and Biochemistry, University of Texas at Dallas, Richardson, Texas, 75080, USA
| | - Amy V Walker
- Department of Chemistry and Biochemistry, University of Texas at Dallas, Richardson, Texas, 75080, USA.,Department of Materials Science and Engineering, University of Texas at Dallas, Richardson, Texas, 75080, USA
| | - David S Bell
- Restek Corporation, 110 Benner Circle, Bellefonte, Pennsylvania, 16823, USA
| | - Matthew R Linford
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, Utah, 84602, USA
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13
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Bell DS. Modern Trends in Mixed-Mode Liquid Chromatography (LC) Columns. LCGC N Am 2021. [DOI: 10.56530/lcgc.na.qo9881n6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Commercialization of columns that provide multiple modes of chromatographic separations have recently been on the rise. For example, combinations of retention modes, such as ion-exchange and reversed-phase, often enable the separation of complex mixtures of analytes not possible using single-mode columns. In this work, recent trends in what is often referred to as “mixed-mode” phase are investigated. Particular attention is paid to recent fundamental research, stationary phase development and design, and areas of application.
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Roychowdhury T, Patel DI, Shah D, Diwan A, Kaykhaii M, Herrington JS, Bell DS, Linford MR. Sputtered silicon solid phase microextraction fibers with a polydimethylsiloxane stationary phase with negligible carry-over and phase bleed. J Chromatogr A 2020; 1623:461065. [DOI: 10.1016/j.chroma.2020.461065] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Revised: 03/21/2020] [Accepted: 03/23/2020] [Indexed: 02/06/2023]
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Goncalves E, Bell DS. Efficacy of semaglutide versus liraglutide in clinical practice. Diabetes Metab 2019; 46:515-517. [PMID: 31606525 DOI: 10.1016/j.diabet.2019.10.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Accepted: 10/02/2019] [Indexed: 11/26/2022]
Affiliation(s)
- E Goncalves
- Diabetes and Thyroid Associates, 2022 Brookwood Baptist Medical Center Drive, Suite #408, Birmingham, AL 35209, United States.
| | - D S Bell
- Southside endocrinology, 1900 Crestwood Blvd, suite 201, Irondale, AL 35210, United States.
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Seidl C, Bell DS, Stoll DR. A study of the re-equilibration of hydrophilic interaction columns with a focus on viability for use in two-dimensional liquid chromatography. J Chromatogr A 2019; 1604:460484. [DOI: 10.1016/j.chroma.2019.460484] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2019] [Revised: 08/26/2019] [Accepted: 08/26/2019] [Indexed: 10/26/2022]
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Vanderlinden K, Desmet G, Bell DS, Broeckhoven K. Detailed efficiency analysis of columns with a different packing quality and confirmation via total pore blocking. J Chromatogr A 2018; 1581-1582:55-62. [PMID: 30446265 DOI: 10.1016/j.chroma.2018.10.052] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Revised: 10/26/2018] [Accepted: 10/29/2018] [Indexed: 11/16/2022]
Abstract
We report on a systematic study involving columns with a clearly different efficiency (4 distinct quality groups) obtained by packing the columns that were C18 bonded and endcapped with a different carbon loading. Using B-term analysis (via peak parking) and theoretical models to estimate the magnitude of the Cm- and Cs-term contributions, it could be concluded that the difference in efficiency among the groups was entirely due to a difference in eddy dispersion. As such, the columns provided an ideal testing ground to verify how well the total pore blocking (TPB)-method can be used to probe differences in packing heterogeneity. In agreement with earlier literature observations, it turns out the TPB-method is much more sensitive to packing heterogeneities than the eddy dispersion (Heddy)-contribution measured under open-pore conditions via B- and C- term subtraction. Typically, differences in Heddy on the order of 0.1-0.5μm translate into a difference on the order of 0.5-2μm in the TPB mode. This confirms the TPB as a powerful technique to make very sensitive measurements of the homogeneity of packed beds.
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Affiliation(s)
- Kim Vanderlinden
- Vrije Universiteit Brussel, Department of Chemical Engineering, Pleinlaan 2, 1050 Brussels, Belgium
| | - Gert Desmet
- Vrije Universiteit Brussel, Department of Chemical Engineering, Pleinlaan 2, 1050 Brussels, Belgium
| | - David S Bell
- MilliporeSigma/Supelco, 595 North Harrison Road, Bellefonte, PA 16823, USA
| | - Ken Broeckhoven
- Vrije Universiteit Brussel, Department of Chemical Engineering, Pleinlaan 2, 1050 Brussels, Belgium.
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Ismail OH, Antonelli M, Ciogli A, De Martino M, Catani M, Villani C, Cavazzini A, Ye M, Bell DS, Gasparrini F. Direct analysis of chiral active pharmaceutical ingredients and their counterions by ultra high performance liquid chromatography with macrocyclic glycopeptide-based chiral stationary phases. J Chromatogr A 2018; 1576:42-50. [PMID: 30266236 DOI: 10.1016/j.chroma.2018.09.029] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2018] [Revised: 09/07/2018] [Accepted: 09/15/2018] [Indexed: 10/28/2022]
Abstract
In this work the simultaneous separation of chiral active pharmaceutical ingredients (API) in salt form from their counterions has been performed by using different high-efficiency macrocyclic glycopeptide-based chiral stationary phases (CSPs). Not only a new zwitterionic vancomycin-based CSP has been prepared (similarly to what was done for teicoplanin) but macrocyclic selectors have also been bonded to sub-2 μm fully porous silica particles through traditional ureidic linkage to obtain versions of CSPs suitable for ultra-high performance applications. The direct separation of chiral APIs and counterions is particularly attracting since it simplifies the workflow traditionally used with reduction of analysis time and costs. The wide selection of macrocyclic antibiotics CSPs now available has allowed to manage different cases that can happen in the simultaneous separation of APIs and their counterions (either cations or anions). Indeed, while inorganic cations are retained on traditional vancomycin- and teicoplanin-based CSPs, inorganic anions are almost unretained (due to Donnan's effect). On the other hand, cations and anions can be both retained on the zwitterionic versions of these CSPs. Afterwards, zwitterionic CSPs allowed the separation of other compounds including N-derivative amino-acids, profens, polyols, sugar anomers, oligosaccharides and inorganic anions/cations opening new perspectives in the use of this family of CSPs.
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Affiliation(s)
- Omar H Ismail
- Dipartimento di Chimica e Tecnologie del Farmaco, "Sapienza" Università di Roma, P. le Aldo Moro 5, 00185 Roma, Italy
| | - Michela Antonelli
- Dipartimento di Chimica e Tecnologie del Farmaco, "Sapienza" Università di Roma, P. le Aldo Moro 5, 00185 Roma, Italy
| | - Alessia Ciogli
- Dipartimento di Chimica e Tecnologie del Farmaco, "Sapienza" Università di Roma, P. le Aldo Moro 5, 00185 Roma, Italy.
| | - Michela De Martino
- Dipartimento di Chimica e Tecnologie del Farmaco, "Sapienza" Università di Roma, P. le Aldo Moro 5, 00185 Roma, Italy
| | - Martina Catani
- Dipartimento di Scienze Chimiche e Farmaceutiche, Università di Ferrara, via L. Borsari 46, 44121 Ferrara, Italy
| | - Claudio Villani
- Dipartimento di Chimica e Tecnologie del Farmaco, "Sapienza" Università di Roma, P. le Aldo Moro 5, 00185 Roma, Italy
| | - Alberto Cavazzini
- Dipartimento di Scienze Chimiche e Farmaceutiche, Università di Ferrara, via L. Borsari 46, 44121 Ferrara, Italy
| | - Michael Ye
- Sigma-Aldrich/Supelco, 595 North Harrison Road, Bellefonte, PA, 16823, United States
| | - David S Bell
- Sigma-Aldrich/Supelco, 595 North Harrison Road, Bellefonte, PA, 16823, United States
| | - Francesco Gasparrini
- Dipartimento di Chimica e Tecnologie del Farmaco, "Sapienza" Università di Roma, P. le Aldo Moro 5, 00185 Roma, Italy.
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Ismail OH, Antonelli M, Ciogli A, Villani C, Cavazzini A, Catani M, Felletti S, Bell DS, Gasparrini F. Future perspectives in high efficient and ultrafast chiral liquid chromatography through zwitterionic teicoplanin-based 2-μm superficially porous particles. J Chromatogr A 2017; 1520:91-102. [PMID: 28911942 DOI: 10.1016/j.chroma.2017.09.008] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Revised: 09/01/2017] [Accepted: 09/04/2017] [Indexed: 10/18/2022]
Abstract
With the aim of pushing forward the limits of high efficient and ultrafast chiral liquid chromatography, a new Chiral Stationary Phase (CSP) has been prepared by covalently bonding the teicoplanin selector on 2.0μm Superficially Porous Particles (SPPs). An already validated bonding protocol, which permits to achieve teicoplanin-based CSPs exhibiting zwitterionic behaviour, has been employed to prepare not only the 2.0μm version of the CSP but also two other analogous CSPs based, respectively, on 2.7μm SPPs and 1.9μm Fully Porous Particles (FPPs). The kinetic performance of these CSPs has been compared through the analysis of both van Deemter curves and kinetic plots by employing in-house packed columns of 4.6mm internal diameter and different lengths (20, 50 and 100mm). In particular on the columns packed with 2.0μm SPPs, extremely large efficiencies were observed for both achiral (>310,000 theoretical plates/meter, N/m; hr: 1.61) and chiral compounds (>290,000 N/m; hr: 1.72) in HILIC conditions. Thanks to their efficiency and enantioselectivity, these CSPs were successfully employed in ultrafast chiral separations. As an example, the enantiomers of haloxyfop were baseline resolved in about 3s, with a resolution higher than 2.0, (flow rate: 8mL/min) on a 2cm long column packed with the 2.0μm chiral SPPs.
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Affiliation(s)
- Omar H Ismail
- Dipartimento di Chimica e Tecnologie del Farmaco, "Sapienza" Università di Roma, P. le Aldo Moro 5, 00185 Roma, Italy.
| | - Michela Antonelli
- Dipartimento di Chimica e Tecnologie del Farmaco, "Sapienza" Università di Roma, P. le Aldo Moro 5, 00185 Roma, Italy
| | - Alessia Ciogli
- Dipartimento di Chimica e Tecnologie del Farmaco, "Sapienza" Università di Roma, P. le Aldo Moro 5, 00185 Roma, Italy
| | - Claudio Villani
- Dipartimento di Chimica e Tecnologie del Farmaco, "Sapienza" Università di Roma, P. le Aldo Moro 5, 00185 Roma, Italy
| | - Alberto Cavazzini
- Dipartimento di Scienze Chimiche e Farmaceutiche, Università di Ferrara, via L. Borsari 46, 44121 Ferrara, Italy
| | - Martina Catani
- Dipartimento di Scienze Chimiche e Farmaceutiche, Università di Ferrara, via L. Borsari 46, 44121 Ferrara, Italy
| | - Simona Felletti
- Dipartimento di Scienze Chimiche e Farmaceutiche, Università di Ferrara, via L. Borsari 46, 44121 Ferrara, Italy
| | - David S Bell
- MilliporeSigma/Supelco, 595 North Harrison Road, Bellefonte, PA 16823, USA
| | - Francesco Gasparrini
- Dipartimento di Chimica e Tecnologie del Farmaco, "Sapienza" Università di Roma, P. le Aldo Moro 5, 00185 Roma, Italy.
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Catani M, Ismail OH, Cavazzini A, Ciogli A, Villani C, Pasti L, Bergantin C, Cabooter D, Desmet G, Gasparrini F, Bell DS. Rationale behind the optimum efficiency of columns packed with new 1.9μm fully porous particles of narrow particle size distribution. J Chromatogr A 2016; 1454:78-85. [DOI: 10.1016/j.chroma.2016.05.037] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2016] [Revised: 05/07/2016] [Accepted: 05/10/2016] [Indexed: 12/12/2022]
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Ward LF, Enders JR, Bell DS, Cramer HM, Wallace FN, McIntire GL. Improved Chiral Separation of Methamphetamine Enantiomers Using CSP-LC–MS-MS. J Anal Toxicol 2016; 40:255-63. [DOI: 10.1093/jat/bkw005] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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Ismail OH, Ciogli A, Villani C, De Martino M, Pierini M, Cavazzini A, Bell DS, Gasparrini F. Ultra-fast high-efficiency enantioseparations by means of a teicoplanin-based chiral stationary phase made on sub-2 μm totally porous silica particles of narrow size distribution. J Chromatogr A 2015; 1427:55-68. [PMID: 26687167 DOI: 10.1016/j.chroma.2015.11.071] [Citation(s) in RCA: 64] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Revised: 11/20/2015] [Accepted: 11/23/2015] [Indexed: 11/26/2022]
Abstract
A new ultra-high performance teicoplanin-based stationary phase was prepared starting from sub-2 μm totally porous silica particles of narrow size distribution. Columns of different lengths were packed at high pressure and a deep and systematic evaluation of kinetic performance, in terms of van Deemter analysis, was performed under different elution conditions (HILIC, POM, RP and NP) by using both achiral and chiral probes. For the achiral probes, the efficiency of the columns at the minimum of the van Deemter curves were very high leading to some 278,000, 270,000, 262,000 and 232,000 plates/m in hydrophilic interaction liquid chromatography (HILIC), polar organic mode (POM), normal phase (NP) and reversed phase (RP) respectively. The lowest plate height, Hmin=3.59 μm (h(/)=1.89), was obtained under HILIC conditions at a flow rate of 1.4 mL/min. Efficiency as high as 200,000-250,000 plates/m (at the optimum flow rate) was obtained in the separation of the enantiomers of chiral probes under HILIC/POM conditions. N-protected amino acids, α-aryloxy acids, herbicides, anti-inflammatory agents were baseline separated on short (2-cm) and ultra-short (1-cm) columns, with analysis time in the order of 1 min. The enantiomers of N-BOC-d,l-methionine were successfully baseline separated in only 11s in HILIC mode. Several examples of fast and efficient resolutions in sub/supercritical fluid chromatography were also obtained for a range of chiral carboxylic acids.
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Affiliation(s)
- Omar H Ismail
- Dipartimento di Chimica e Tecnologie del Farmaco, Sapienza Università di Roma, P.le Aldo Moro 5, 00185 Roma, Italy
| | - Alessia Ciogli
- Dipartimento di Chimica e Tecnologie del Farmaco, Sapienza Università di Roma, P.le Aldo Moro 5, 00185 Roma, Italy
| | - Claudio Villani
- Dipartimento di Chimica e Tecnologie del Farmaco, Sapienza Università di Roma, P.le Aldo Moro 5, 00185 Roma, Italy
| | - Michela De Martino
- Dipartimento di Chimica e Tecnologie del Farmaco, Sapienza Università di Roma, P.le Aldo Moro 5, 00185 Roma, Italy
| | - Marco Pierini
- Dipartimento di Chimica e Tecnologie del Farmaco, Sapienza Università di Roma, P.le Aldo Moro 5, 00185 Roma, Italy
| | - Alberto Cavazzini
- Dipartimento di Scienze Chimiche e Farmaceutiche, Università di Ferrara, via L. Borsari 46, 44121 Ferrara, Italy
| | - David S Bell
- Sigma-Aldrich/Supelco, 595 North Harrison Road, Bellefonte, PA 16823, USA
| | - Francesco Gasparrini
- Dipartimento di Chimica e Tecnologie del Farmaco, Sapienza Università di Roma, P.le Aldo Moro 5, 00185 Roma, Italy.
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Barhate CL, Wahab MF, Breitbach ZS, Bell DS, Armstrong DW. High efficiency, narrow particle size distribution, sub-2 μm based macrocyclic glycopeptide chiral stationary phases in HPLC and SFC. Anal Chim Acta 2015; 898:128-37. [PMID: 26526918 DOI: 10.1016/j.aca.2015.09.048] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Revised: 09/21/2015] [Accepted: 09/26/2015] [Indexed: 12/01/2022]
Abstract
State of the art chiral chromatography still employs 3-5 μm bonded or immobilized chiral selectors in 10-25 cm columns. With the availability of 1.9 μm narrow particle size distribution (NPSD) silica, it is now possible to make ever shorter, high efficiency columns practical for sub-minute chiral separations. Three macrocyclic glycopeptides (teicoplanin, teicoplanin aglycone, and vancomycin) were bonded onto 1.9 μm NPSD particles. Such packed columns had ∼80% lower backpressure as compared to polydisperse (PD) 1.7 μm silica materials when using the same mobile phase. The decreased backpressure allowed for diminution of frictional heating and allowed for the use of the 1.9 μm NPSD particle based columns at high flow rates. The 1.9 μm NPSD particle based columns showed up to 190,000 plates m(-1) for chiral molecules and 210,000 plates m(-1) for achiral probes. Representative enantiomeric separations are shown for wide classes of compounds, including different types of amino acids, β-blockers, and pharmaceutically important heterocyclic compounds such as oxazolidinones. Applications in three liquid chromatography modes, namely, reversed phase, polar organic mode and normal phase chiral separations were shown with resolution values ranging from 1.5 to 5.7. Additionally, the same columns were used with supercritical fluid chromatography (SFC) for ultrafast separations.
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Affiliation(s)
- Chandan L Barhate
- Department of Chemistry and Biochemistry, University of Texas at Arlington, 700 Planetarium Place, Arlington, TX 76019-0065, USA
| | - M Farooq Wahab
- Department of Chemistry and Biochemistry, University of Texas at Arlington, 700 Planetarium Place, Arlington, TX 76019-0065, USA
| | - Zachary S Breitbach
- Department of Chemistry and Biochemistry, University of Texas at Arlington, 700 Planetarium Place, Arlington, TX 76019-0065, USA
| | - David S Bell
- Sigma-Aldrich/Supelco, 595 North Harrison Road, Bellefonte, PA 16823, USA
| | - Daniel W Armstrong
- Department of Chemistry and Biochemistry, University of Texas at Arlington, 700 Planetarium Place, Arlington, TX 76019-0065, USA.
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DiNicolantonio JJ, Fares H, Niazi AK, Chatterjee S, D'Ascenzo F, Cerrato E, Biondi-Zoccai G, Lavie CJ, Bell DS, O'Keefe JH. β-Blockers in hypertension, diabetes, heart failure and acute myocardial infarction: a review of the literature. Open Heart 2015; 2:e000230. [PMID: 25821584 PMCID: PMC4371808 DOI: 10.1136/openhrt-2014-000230] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Revised: 01/16/2015] [Accepted: 02/15/2015] [Indexed: 11/12/2022] Open
Abstract
β-Blockers (BBs) are an essential class of cardiovascular medications for
reducing morbidity and mortality in patients with heart failure (HF). However, a
large body of data indicates that BBs should not be used as first-line therapy for
hypertension (HTN). Additionally, new data have questioned the role of BBs in the
treatment of stable coronary heart disease (CHD). However, these trials mainly tested
the non-vasodilating β1 selective BBs (atenolol and metoprolol)
which are still the most commonly prescribed BBs in the USA. Newer generation BBs,
such as the vasodilating BBs carvedilol and nebivolol, have been shown not only to be
better tolerated than non-vasodilating BBs, but also these agents do not increase the
risk of diabetes mellitus (DM), atherogenic dyslipidaemia or weight gain. Moreover,
carvedilol has the most evidence for reducing morbidity and mortality in patients
with HF and those who have experienced an acute myocardial infarction (AMI). This
review discusses the cornerstone clinical trials that have tested BBs in the settings
of HTN, HF and AMI. Large randomised trials in the settings of HTN, DM and stable CHD
are still needed to establish the role of BBs in these diseases, as well as to
determine whether vasodilating BBs are exempt from the disadvantages of
non-vasodilating BBs.
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Affiliation(s)
| | - Hassan Fares
- John Ochsner Heart and Vascular Institute, Ochsner Clinical School- The University of Queensland School of Medicine , New Orleans, Louisiana , USA
| | | | | | - Fabrizio D'Ascenzo
- University of Turin, Citta Della Salute e Della Scienza , Torino , Italy
| | - Enrico Cerrato
- University of Turin, Citta Della Salute e Della Scienza , Torino , Italy
| | | | - Carl J Lavie
- John Ochsner Heart and Vascular Institute, Ochsner Clinical School- The University of Queensland School of Medicine , New Orleans, Louisiana , USA ; Department of Preventive Medicine , Pennington Biomedical Research Center , Baton Rouge, Louisiana , USA
| | - David S Bell
- Southside Endocrinology, University of Alabama at Birmingham
| | - James H O'Keefe
- Mid America Heart Institute at Saint Luke's Hospital, University of Missouri-Kansas City , Kansas City, Missouri , USA
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Gritti F, Bell DS, Guiochon G. Particle size distribution and column efficiency. An ongoing debate revived with 1.9μm Titan-C18 particles. J Chromatogr A 2014; 1355:179-92. [DOI: 10.1016/j.chroma.2014.06.029] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Revised: 06/06/2014] [Accepted: 06/10/2014] [Indexed: 10/25/2022]
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Li X, Uboh CE, Soma LR, Liu Y, Guan F, Aurand CR, Bell DS, You Y, Chen J, Maylin GA. Sensitive hydrophilic interaction liquid chromatography/tandem mass spectrometry method for rapid detection, quantification and confirmation of cathinone-derived designer drugs for doping control in equine plasma. Rapid Commun Mass Spectrom 2014; 28:217-229. [PMID: 24338970 DOI: 10.1002/rcm.6778] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Revised: 10/29/2013] [Accepted: 10/31/2013] [Indexed: 06/03/2023]
Abstract
RATIONALE Cathinone derivatives are new amphetamine-like stimulants that can evade detection when presently available methods are used for doping control. To prevent misuse of these banned substances in racehorses, development of a liquid chromatography/tandem mass spectrometry (LC/MS/MS) method became the impetus for undertaking this study. METHODS Analytes were recovered via liquid-liquid extraction using methyl tert-butyl ether. Analyte separation was achieved on a hydrophilic interaction column using liquid chromatography and mass analysis was performed on a QTRAP mass spectrometer in positive electrospray ionization (ESI) mode with multiple reaction monitoring (MRM). Analyte identification was carried out by screening for a specified MRM transition. Quantification was conducted using an internal standard. Confirmation was performed by establishing a match in retention time and ion intensity ratios comparison. RESULTS The method was linear over the range 0.2-50 ng/mL. The specificity was evaluated by analysis of six different batches of blank plasma and those spiked with each analyte (0.2 ng/mL). The recovery of analytes from plasma at three different concentrations was >70%. The limits of detection, quantification and confirmation were 0.02-0.05, 0.2-1.0 and 0.2-10 ng/mL, respectively. The matrix effect was insignificant. The intra-day and inter-day precision were 1.94-12.08 and 2.58-13.32%, respectively. CONCLUSIONS The method is routinely employed in screening for the eleven analytes in post-competition samples collected from racehorses in Pennsylvania to enforce the ban on the use of these performance-enhancing agents in racehorses. The method is sensitive, fast, effective and reliably reproducible.
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Affiliation(s)
- Xiaoqing Li
- University of Pennsylvania, School of Veterinary Medicine, Department of Clinical Studies, New Bolton Center Campus, Kennett Square, PA, 19348, USA
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Kotoni D, Ciogli A, Villani C, Bell DS, Gasparrini F. Separation of complex sugar mixtures on a hydrolytically stable bidentate urea-type stationary phase for hydrophilic interaction near ultra high performance liquid chromatography. J Sep Sci 2014; 37:527-35. [DOI: 10.1002/jssc.201301008] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2013] [Revised: 12/09/2013] [Accepted: 12/14/2013] [Indexed: 11/08/2022]
Affiliation(s)
- Dorina Kotoni
- Dipartimento di Chimica e Tecnologie del Farmaco; Sapienza Università di Roma; Roma Italy
| | - Alessia Ciogli
- Dipartimento di Chimica e Tecnologie del Farmaco; Sapienza Università di Roma; Roma Italy
| | - Claudio Villani
- Dipartimento di Chimica e Tecnologie del Farmaco; Sapienza Università di Roma; Roma Italy
| | | | - Francesco Gasparrini
- Dipartimento di Chimica e Tecnologie del Farmaco; Sapienza Università di Roma; Roma Italy
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Kotoni D, Villani C, Bell DS, Capitani D, Campiglia P, Gasparrini F. Bidentate urea-based chiral selectors for enantioselective high performance liquid chromatography: Synthesis and evaluation of “Crab-like” stationary phases. J Chromatogr A 2013; 1297:157-67. [DOI: 10.1016/j.chroma.2013.04.083] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Revised: 04/24/2013] [Accepted: 04/29/2013] [Indexed: 11/15/2022]
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Abstract
OBJECTIVE This study sought to examine long-term health, symptom, and disability outcomes among patients with chronic fatigue syndrome (CFS) by comparing those diagnosed with CFS 25 years ago with healthy controls. METHOD Of the 25 participants diagnosed with CFS 25 years ago, 5 self-reported that they maintained a diagnosis of CFS, while 20 reported no longer having a diagnosis. These two groups were compared with healthy controls on outcomes related to functioning and symptom severity. RESULTS Those who remitted from CFS showed significantly more impairment on 21 out of 23 outcomes compared with controls. On 17 outcomes, those who remitted had nonsignificant differences in impairment compared to those who maintained a CFS diagnosis. CONCLUSIONS Findings from this study suggest that over time many individuals will not maintain a CFS diagnosis but will not return to their premorbid level of functioning.
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Lee LL, Lin L, Bell DS, Levine S, Hanson MR. Sensitivity of PCR assays for murine gammaretroviruses and mouse contamination in human blood samples. PLoS One 2012; 7:e37482. [PMID: 22629404 PMCID: PMC3357399 DOI: 10.1371/journal.pone.0037482] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2012] [Accepted: 04/24/2012] [Indexed: 11/19/2022] Open
Abstract
Gammaretroviruses related to murine leukemia virus (MLV) have variously been reported to be present or absent in blood from chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME) patients and healthy controls. Using subjects from New York State, we have investigated by PCR methods whether MLV-related sequences can be identified in nucleic acids isolated from whole blood or from peripheral blood mononuclear cells (PBMCs) or following PBMC culture. We have also passaged the prostate cancer cell line LNCaP following incubation with plasma from patients and controls and assayed nucleic acids for viral sequences. We have used 15 sets of primers that can effectively amplify conserved regions of murine endogenous and exogenous retrovirus sequences. We demonstrate that our PCR assays for MLV-related gag sequences and for mouse DNA contamination are extremely sensitive. While we have identified MLV-like gag sequences following PCR on human DNA preparations, we are unable to conclude that these sequences originated in the blood samples.
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Affiliation(s)
- Li Ling Lee
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, United States of America
| | - Lin Lin
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, United States of America
| | - David S. Bell
- Department of Pediatrics, State University of New York, Buffalo, New York, United States of America
| | - Susan Levine
- Private Practice, New York, New York, United States of America
| | - Maureen R. Hanson
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, United States of America
- * E-mail:
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Hanson MR, Lee LL, Lin L, Bell DE, Ruppert D, Bell DS. Detection of MLV-like gag sequences in blood samples from a New York state CFS cohort. Retrovirology 2011. [PMCID: PMC3112714 DOI: 10.1186/1742-4690-8-s1-a234] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Carruthers BM, van de Sande MI, De Meirleir KL, Klimas NG, Broderick G, Mitchell T, Staines D, Powles ACP, Speight N, Vallings R, Bateman L, Baumgarten-Austrheim B, Bell DS, Carlo-Stella N, Chia J, Darragh A, Jo D, Lewis D, Light AR, Marshall-Gradisnik S, Mena I, Mikovits JA, Miwa K, Murovska M, Pall ML, Stevens S. Myalgic encephalomyelitis: International Consensus Criteria. J Intern Med 2011; 270:327-38. [PMID: 21777306 PMCID: PMC3427890 DOI: 10.1111/j.1365-2796.2011.02428.x] [Citation(s) in RCA: 695] [Impact Index Per Article: 53.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The label 'chronic fatigue syndrome' (CFS) has persisted for many years because of the lack of knowledge of the aetiological agents and the disease process. In view of more recent research and clinical experience that strongly point to widespread inflammation and multisystemic neuropathology, it is more appropriate and correct to use the term 'myalgic encephalomyelitis' (ME) because it indicates an underlying pathophysiology. It is also consistent with the neurological classification of ME in the World Health Organization's International Classification of Diseases (ICD G93.3). Consequently, an International Consensus Panel consisting of clinicians, researchers, teaching faculty and an independent patient advocate was formed with the purpose of developing criteria based on current knowledge. Thirteen countries and a wide range of specialties were represented. Collectively, members have approximately 400 years of both clinical and teaching experience, authored hundreds of peer-reviewed publications, diagnosed or treated approximately 50 000 patients with ME, and several members coauthored previous criteria. The expertise and experience of the panel members as well as PubMed and other medical sources were utilized in a progression of suggestions/drafts/reviews/revisions. The authors, free of any sponsoring organization, achieved 100% consensus through a Delphi-type process. The scope of this paper is limited to criteria of ME and their application. Accordingly, the criteria reflect the complex symptomatology. Operational notes enhance clarity and specificity by providing guidance in the expression and interpretation of symptoms. Clinical and research application guidelines promote optimal recognition of ME by primary physicians and other healthcare providers, improve the consistency of diagnoses in adult and paediatric patients internationally and facilitate clearer identification of patients for research studies.
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Affiliation(s)
- B M Carruthers
- Department of Physiology and Medicine, Vrije University of Brussels, Himmunitas Foundation, Brussels, Belgium.
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Jason L, Porter N, Shelleby E, Till L, Bell DS, Lapp CW, Rowe K, De Meirleir K. Severe versus Moderate criteria for the new pediatric case definition for ME/CFS. Child Psychiatry Hum Dev 2009; 40:609-20. [PMID: 19513826 DOI: 10.1007/s10578-009-0147-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2009] [Accepted: 05/25/2009] [Indexed: 10/20/2022]
Abstract
The new diagnostic criteria for pediatric ME/CFS are structurally based on the Canadian Clinical Adult case definition, and have more required specific symptoms than the (Fukuda et al. Ann Intern Med 121:953-959, 1994) adult case definition. Physicians specializing in pediatric ME/CFS referred thirty-three pediatric patients with ME/CFS and 21 youth without the illness. Those who met ME/CFS criteria were separated into Severe and Moderate categories. Significant differences were found for symptoms within each of the six major categories: fatigue, post-exertional malaise, sleep, pain, neurocognitive difficulties, and autonomic/neuroendocrine/immune manifestations. In general, the results showed participants who met the Severe ME/CFS criteria reported the highest scores, the Moderate ME/CFS group show scores that were a little lower, and the control group evidenced the lowest scores. Findings indicate that the Pediatric Case Definition for ME/CFS can distinguish between those with this illness and controls, and between those with Severe versus Moderate manifestations of the illness.
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Affiliation(s)
- Leonard Jason
- Center for Community Research, DePaul University, Chicago, IL 60614, USA.
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Bell DS. Controversy Corner: Quieta movere magna merces videbatur: The Bite and Bark of Medico-Legal Argument. AUST J FORENSIC SCI 2009. [DOI: 10.1080/00450619609411356] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Bell DS. Forensic Medicine and the Law. AUST J FORENSIC SCI 2009. [DOI: 10.1080/00450619609411358] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Bell DS. Guide to the Seeker. AUST J FORENSIC SCI 2009. [DOI: 10.1080/00450619609411346] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Bell DS. Guide to the Seeker. AUST J FORENSIC SCI 2009. [DOI: 10.1080/00450619909410780] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Jason LA, Porter N, Shelleby E, Bell DS, Lapp CW, Rowe K, De Meirleir K. A Case Definition for Children with Myalgic Encephalomyelitis/Chronic Fatigue Syndrome. Clinical medicine Pediatrics 2008. [DOI: 10.4137/cmped.s978] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The case definition for chronic fatigue syndrome was developed for adults (Fukuda et al. 1994), and this case definition may not be appropriate for use with children and adolescents. The lack of application of a consistent pediatric definition for this illness and the lack of a reliable instrument to assess it might lead to studies which lack sensitivity and specificity. In this article, a case definition is presented that has been endorsed by the International Association of ME/CFS.
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Nuckols TK, Bell DS, Paddock SM, Hilborne LH. Contributing factors identified by hospital incident report narratives. Qual Saf Health Care 2008; 17:368-72. [DOI: 10.1136/qshc.2007.023721] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
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Brondz I, Ekeberg D, Høiland K, Bell DS, Annino AR. The real nature of the indole alkaloids in Cortinarius infractus: Evaluation of artifact formation through solvent extraction method development. J Chromatogr A 2007; 1148:1-7. [PMID: 17391682 DOI: 10.1016/j.chroma.2007.02.074] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2006] [Revised: 02/07/2007] [Accepted: 02/14/2007] [Indexed: 11/28/2022]
Abstract
This study was triggered by the absence of infractine in EtOH extracts of Cortinarius infractus and the presence of the beta-carboline-1-propionic acid [I. Brondz, K. Høiland, D.S. Bell, A.R. Annino, TheReporter, Supelco 24 (3) (2006) 6]. In previous studies it was determined that C. infractus contained indole alkaloid substances of the infractine group [W. Steglich, L. Kopanski, M. Wolf, M. Moser, G. Tegtmeyer, Indolalkaloide aus dem Blaetterpilz Cortinarius infractus (Agaricales). Tetrahedron Lett. 25 (1984) 2341]. It is quite possible that some of these compounds do not exist in any other mushroom species and therefore they could prove to be valuable chemotaxonomic markers. Proper classification of this species requires that the chemical markers are identified correctly. In this study, the presence of several compounds previously found in C. infractus (Pers.: Fr.) Fr. is questioned. In this investigation, it was shown by HPLC-MS that infractine and 6-hydroxyinfractine, previously described as constituents of C. infractus, were artifacts produced during the extraction process. Also, the molecular species that participate in the artefact formation were identified. Infractine and 6-hydroxyinfractine, reported earlier in C. infractus, originate from the precursor (pre-infractine) beta-carboline-1-propionic acid during extraction with methanol.
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Affiliation(s)
- Ilia Brondz
- Norwegian University of Life Sciences, Department of Chemistry, Biotechnology and Food Science, P.O. Box 5003, N-1432 As, Norway.
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Brondz I, Ekeberg D, Bell DS, Annino AR, Hustad JA, Svendsen R, Vlachos V, Oakley P, Langley GJ, Mohini T, Amaury CG, Mikhalitsyn F. Nature of the main contaminant in the drug primaquine diphosphate: SFC and SFC–MS methods of analysis. J Pharm Biomed Anal 2007; 43:937-44. [PMID: 17079107 DOI: 10.1016/j.jpba.2006.09.017] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2006] [Revised: 09/07/2006] [Accepted: 09/08/2006] [Indexed: 11/15/2022]
Abstract
The drug primaquine diphosphate is used for causative treatment of malaria. Using HPLC-MS and GC-MS, this research group was previously able to show that the main contaminant of primaquine is the positional isomer quinocide [I. Brondz, D. Mantzilas, U. Klein, D. Ekeberg, E. Hvattum, M.N. Lebedeva, F.S. Mikhailitsyn, G.D. Soulimanov, J. Roe, J. Chromatogr. B: Anal. Technol. Biomed. Life Sci. 800 (2004) 211-223; I. Brondz, U. Klein, D. Ekeberg, D. Mantzilas, E. Hvattum, H. Schultz, F. S. Mikhailitsyn, Asian J. Chem. 17 (2005) 1678-1688]. Primaquine and quinocide are highly toxic substances which can have a number of side effects upon use in medical treatment. A standard for quinocide is not typically commercially available. In the present work, supercritical fluid chromatography-mass spectrometry (SFC-MS) with two different columns was used to achieve a shorter analysis time for the separation between the positional isomers quinocide and primaquine in primaquine diphosphate and to elucidate additional information about differences in their MS fragmentation. Unlike using HPLC-MS, it was possible to achieve the differential fragmentation of positional isomers at branching points using the SFC-MS technique. The desired short analysis time was achieved using SFC equipped with a Discovery HS F5 column and the differential fragmentation of positional isomers during SFC-MS provides information on the differences in the structure of these substances. Using a Chiralpak AD-H chiral column, it was possible to resolve the enantiomers in primaquine and separate quinocide from those enantiomers.
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Affiliation(s)
- Ilia Brondz
- University of Life Sciences, Department of Chemistry, Biotechnology and Food Science, As, Norway.
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Bell DS. Controversy Corner: Quieta movere magna merces videbatur. AUST J FORENSIC SCI 2006. [DOI: 10.1080/00450610609410637] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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Bell DS, Cramer HM, Jones AD. Rational method development strategies on a fluorinated liquid chromatography stationary phase: Mobile phase ion concentration and temperature effects on the separation of ephedrine alkaloids. J Chromatogr A 2005; 1095:113-8. [PMID: 16275290 DOI: 10.1016/j.chroma.2005.08.004] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2005] [Revised: 07/29/2005] [Accepted: 08/01/2005] [Indexed: 11/24/2022]
Abstract
Fluorinated, silica-based stationary phases are becoming increasingly popular alternatives to traditional alkyl phases owing to their differential selectivity and retention for a variety of analyte classes. In this report, the ion-exchange mechanisms characteristic of a fluorinated phase are exploited to rapidly develop separation conditions for ephedrine alkaloids and synephrine using a mobile phase compatible with mass spectrometry. A linear relationship of basic analyte retention with the reciprocal of ammonium acetate concentration is first established. This linear relationship can then be used to optimize retention and selectivity in just two experiments. The relationship of retention with temperature is also explored. Greater retention with increasing temperature is demonstrated on the fluorinated phase at high percentages of organic modifier, which is in contrast to behavior observed in typical reversed-phase separations. The unexpected observation is explicated based on the reduction in solvent solvating power with increasing temperature. As solvation power of the mobile phase decreases, decreased solvation of both mobile phase and ionized surface groups of the stationary phase leads to stronger interactions between analyte and stationary phase. Both mobile phase ion concentration and temperature are shown to be powerful tools for the manipulation of analyte retention and selectivity.
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Affiliation(s)
- David S Bell
- Department of Chemistry, The Pennsylvania State University, University Park, 16802, USA.
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Bell DS, Jones AD. Solute attributes and molecular interactions contributing to “U-shape” retention on a fluorinated high-performance liquid chromatography stationary phase. J Chromatogr A 2005; 1073:99-109. [PMID: 15909511 DOI: 10.1016/j.chroma.2004.08.163] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The structural attributes and molecular interactions contributing to "U-shape" retention on pentafluorophenylpropyl (PFPP) HPLC stationary phases are systematically investigated. Only basic analytes exhibit retention that increases with the acetonitrile content in mixtures of acetonitrile and aqueous ammonium acetate, with some basic analytes not eluting at all from PFPP columns using 100% acetonitrile. U-shaped retention as a function of mobile phase acetonitrile content was more dramatic on a PFPP column relative to C18. Retention of the quaternary ammonium salt bretylium on these stationary phases and on the same bare silica support showed minimal influence of ion-exchange mechanisms on the C18 phase, however, a significant influence of ion-exchange mechanisms was observed for both PFPP and bare silica. The retention of bretylium on PFPP was only slightly less than on bare silica. These findings suggest ion-exchange mechanisms dominate retention of basic analytes in the high acetonitrile realm on PFPP. The PFPP stationary phase exhibits a substantial increase in effects of ionized surface silanol groups compared to the alkyl phase despite similar surface coverage. Retention of some basic analytes on a PFPP phase was enhanced relative to retention on silica alone, and implicates other dispersive interactions that might be exploited for selectivity different from either alkyl phases or silica alone.
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Affiliation(s)
- David S Bell
- Department of Chemistry, The Pennsylvania State University, University Park, PA 16802, USA.
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Abstract
OBJECTIVE To emphasize that measurement of a C-peptide level can be critical in the diagnosis and appropriate management of patients with diabetes mellitus. METHODS We present a series of clinical cases in which glycemic control proved challenging, and we discuss the underlying pathophysiologic features of type 1 versus type 2 diabetes. RESULTS In a series of 12 illustrative cases, suboptimal control of blood glucose levels in patients with diabetes prompted further investigation. Assessment of C-peptide levels helped determine a precise diagnosis of type 1 or type 2 diabetes, information that was pivotal in choosing treatment options and improving the outcome. These examples show that the age of the patient at the time of diagnosis of diabetes does not necessarily indicate the type of diabetes that is present. CONCLUSION Clinicians should be aware of the importance of establishing whether patients have type 1 or type 2 diabetes mellitus and the implications of that distinction on the effectiveness of therapeutic strategies.
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Affiliation(s)
- D S Bell
- University of Alabama at Birmingham School of Medicine, Department of Medicine, Division of Endocrinology and Metabolism, Birmingham, Alabama, USA
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Abstract
OBJECTIVE To assess the frequency of severe hypoglycemia in patients with non-insulin-dependent diabetes mellitus (NIDDM). METHODS We surveyed a single diabetologist's clinical practice of consecutive patients with NIDDM during a 3-month period. RESULTS Of the 262 study participants interviewed, 172 insulin-using and 90 sulfonylurea-using patients were asked whether they had ever had hypoglycemia severe enough to require the assistance of another person. Of the 90 sulfonylurea-treated patients with NIDDM, 3 (3.3%) reported experiencing severe hypoglycemia on one occasion only. Of the 172 insulin-utilizing patients, 13 (7.6%) had had severe hypoglycemic episodes--8 on one occasion only (5 of these had been iatrogenic circumstances and 3 had been precipitated by exercise or lack of food). Five insulin-requiring patients reported multiple bouts of severe hypoglycemia. With one exception, all patients were thin, and C peptide levels were low or undetectable. CONCLUSION On the basis of this study, we conclude that severe hypoglycemia is extremely uncommon in NIDDM. When it occurs, it is usually accidental and seldom recurs. Patients with multiple bouts of severe hypoglycemia have almost complete insulin deficiency. Thus, aggressive treatment of NIDDM to avoid diabetic complications is rarely associated with severe hypoglycemia and is usually well tolerated.
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Affiliation(s)
- D S Bell
- University of Alabama at Birmingham, School of Medicine, Department of Medicine, Birmingham, Alabama, USA
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