1
|
Burdová H, Pilnaj D, Kuráň P. Application of low-energy-capable electron ionization with high-resolution mass spectrometer for characterization of pyrolysis oils from plastics. J Chromatogr A 2023; 1711:464445. [PMID: 37857155 DOI: 10.1016/j.chroma.2023.464445] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2023] [Revised: 10/04/2023] [Accepted: 10/10/2023] [Indexed: 10/21/2023]
Abstract
Pyrolysis is a promising way of waste transformation into new valuable products. Pyrolytic oil is a mixture of hundreds of compounds and it requires detailed and accurate characterization for future applications. One of the most widely used techniques is mass spectrometry in combination with electron ionization. Tuneable ionization provides benefits including additional structural information and validation of molecular ion due to limited fragmentation at lower energies compared to conventional 70 eV, which provides spectral matches towards libraries. This approach was applied to the compounds identification and group characterization of virgin plastics polyvinyl chloride (PVC), polypropylene (PP), polystyrene (PS), high-density polyethylene (HDPE), low-density polyethylene (LDPE) and their mixture. The use of lower ionization energy was beneficial for distinction of alkanes, iso-alkanes and aromatics. On the contrary to 70 eV, significantly higher fragmentation in branching of iso-alkanes at 12 eV was observed with higher yield of molecular ion also for n-alkane. More than 50 % of detected peaks were identified up to the retention time of icosane. The main analytes of produced pyrolysis oil were monoaromatic (from PVC and PS), alkene/cycloalkane (from PP and mixture). In the case of HDPE and LDPE the main compounds were 1-n-alkenes and n-alkanes. The applied methodology reveals compound group, carbon chain length and degree of unsaturation with higher confidence and success rate compared to traditional nominal mass 70 eV datasets.
Collapse
Affiliation(s)
- Hana Burdová
- Faculty of Environment, Jan Evangelista Purkyně University in Ústí and Labem, Pasteurova 3632/15, Ústí nad Labem 40096, Czech Republic.
| | - Dominik Pilnaj
- Faculty of Environment, Jan Evangelista Purkyně University in Ústí and Labem, Pasteurova 3632/15, Ústí nad Labem 40096, Czech Republic; Faculty of electrotechnology, Czech Technical University in Prague, Technická 2, 166 27, Prague 6, Czech Republic
| | - Pavel Kuráň
- Faculty of Environment, Jan Evangelista Purkyně University in Ústí and Labem, Pasteurova 3632/15, Ústí nad Labem 40096, Czech Republic
| |
Collapse
|
2
|
Keen B, Cawley A, Reedy B, Fu S. Metabolomics in clinical and forensic toxicology, sports anti-doping and veterinary residues. Drug Test Anal 2022; 14:794-807. [PMID: 35194967 PMCID: PMC9544538 DOI: 10.1002/dta.3245] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2021] [Revised: 02/13/2022] [Accepted: 02/15/2022] [Indexed: 11/29/2022]
Abstract
Metabolomics is a multidisciplinary field providing workflows for complementary approaches to conventional analytical determinations. It allows for the study of metabolically related groups of compounds or even the study of novel pathways within the biological system. The procedural stages of metabolomics; experimental design, sample preparation, analytical determinations, data processing and statistical analysis, compound identification and validation strategies are explored in this review. The selected approach will depend on the type of study being conducted. Experimental design influences the whole metabolomics workflow and thus needs to be properly assessed to ensure sufficient sample size, minimal introduced and biological variation and appropriate statistical power. Sample preparation needs to be simple, yet potentially global in order to detect as many compounds as possible. Analytical determinations need to be optimised either for the list of targeted compounds or a universal approach. Data processing and statistical analysis approaches vary widely and need to be better harmonised for review and interpretation. This includes validation strategies that are currently deficient in many presented workflows. Common compound identification approaches have been explored in this review. Metabolomics applications are discussed for clinical and forensic toxicology, human and equine sports anti-doping and veterinary residues.
Collapse
Affiliation(s)
- Bethany Keen
- Centre for Forensic ScienceUniversity of Technology SydneyBroadwayNew South WalesAustralia
| | - Adam Cawley
- Australian Racing Forensic LaboratoryRacing NSWSydneyNew South WalesAustralia
| | - Brian Reedy
- School of Mathematical and Physical SciencesUniversity of Technology SydneyBroadwayNew South WalesAustralia
| | - Shanlin Fu
- Centre for Forensic ScienceUniversity of Technology SydneyBroadwayNew South WalesAustralia
| |
Collapse
|
3
|
Redhu N, Thakur Z. Network biology and applications. Bioinformatics 2022. [DOI: 10.1016/b978-0-323-89775-4.00024-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
|
4
|
Fialkov AB, Ikonen E, Laaksonen T, Amirav A. GC-MS with photoionization of cold molecules in supersonic molecular beams-Approaching the softest ionization method. JOURNAL OF MASS SPECTROMETRY : JMS 2020; 55:e4516. [PMID: 32567120 DOI: 10.1002/jms.4516] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 03/18/2020] [Accepted: 03/23/2020] [Indexed: 06/11/2023]
Abstract
A new type of photoionization ion source was developed for the ionization of cold molecules in supersonic molecular beams (named Cold PI). The system was based on a GC-MS with supersonic molecular beams and its fly-through EI of cold molecules ion source (Cold EI) plus quadrupole mass analyzer. A continuously operated deuterium VUV photoionization lamp was added and placed above and between the supersonic nozzle and skimmer whereas the Cold EI ion source served only as a portion of the ion transfer ion optics. The supersonic nozzle and skimmer were voltage biased and the VUV light crossed the supersonic expansion about 10 mm from the nozzle. We obtained over three orders of magnitude enhancement in the relative abundance of the molecular ion of squalane in Cold PI versus in photoionization of this compound as a thermal compound. Accordingly, we also proved that standard photoionization is not as soft ionization method as previously perceived for large compounds. We found that Cold PI is as soft as and possibly softer than field ionization; thus, it could be the softest known ionization method. The ionization yield was about 200-300 times weaker than with Cold EI yet our limit of detection was about 200 femtogram in SIM mode for cholesterol and pyrene which is reasonable. Practically, all hydrocarbons gave only molecular ions with rather uniform response whereas alcohols gave some molecular ions plus major fragment ions particularly with a loss of water (similarly to field ionization). We tested Cold PI in the GC-MS analysis of diesel fuels and analyzed the time averaged data for group type information. We also found that we can analyze the diesel fuels by fast under 20-s flow injection analysis in which the generated averaged mass spectrum of molecular ions only could serve for the characterization of fuels.
Collapse
Affiliation(s)
| | | | | | - Aviv Amirav
- School of Chemistry, Tel Aviv University, Tel Aviv, 69978, Israel
| |
Collapse
|
5
|
Gruber B, David F, Sandra P. Capillary gas chromatography-mass spectrometry: Current trends and perspectives. Trends Analyt Chem 2020. [DOI: 10.1016/j.trac.2019.04.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
|
6
|
Margolin Eren KJ, Fialkov AB, Keshet U, Tsizin S, Amirav A. Doubly Charged Molecular Ions in GC-MS with Cold EI. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2020; 31:347-354. [PMID: 32031407 DOI: 10.1021/jasms.9b00067] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We report the finding of doubly charged molecular ions in a range of relatively large molecules including hydrocarbons upon their electron ionization as vibrationally cold molecules in supersonic molecular beams (SMB) (also named as Cold EI). Furthermore, we also report the detection by mass spectrometry of triply charged molecular ions in large PAHs such as decacyclene and ovalene upon their cooling in SMB. We found that the relative abundance of doubly charged molecular ions strongly depends on the internal vibrational cooling. While after some vibrational cooling the fragmentation pattern became cooling independent, the relative abundance of the doubly charged molecular ions was noticeably increased upon further cooling via increasing of the cooling make-up gas flow rate. In addition, the relative abundance of the doubly charged molecular ions was strongly increased with the compounds' size, and its electron energy threshold was lower than expected. These observations indicate a new mechanism that involves two separate electron ionization processes in the same compound, most likely with the same electron but at two separate atoms (places) in large molecules, to reduce Coulombic repulsion energy that can lead to fragmentation into two singly charged ions. These findings are shedding new light on electron ionization mass spectra. Accordingly, electron ionization mass spectra are the result of three separate mechanisms with relative magnitudes that depend on the compound size: (a) single electron ionization; (b) double electron ionization; and (c) single electron ionization with subsequent internal excitation by the same ionizing electron in another place.
Collapse
Affiliation(s)
| | | | - Uri Keshet
- School of Chemistry , Tel Aviv University , Tel Aviv 6997801 , Israel
| | - Svetlana Tsizin
- School of Chemistry , Tel Aviv University , Tel Aviv 6997801 , Israel
| | - Aviv Amirav
- School of Chemistry , Tel Aviv University , Tel Aviv 6997801 , Israel
- Aviv Analytical Ltd. , 24 Hanagar Street Hod , Hasharon 4527713 , Israel
| |
Collapse
|
7
|
Pua A, Lau H, Liu SQ, Tan LP, Goh RMV, Lassabliere B, Leong KC, Sun J, Cornuz M, Yu B. Improved detection of key odourants in Arabica coffee using gas chromatography-olfactometry in combination with low energy electron ionisation gas chromatography-quadrupole time-of-flight mass spectrometry. Food Chem 2019; 302:125370. [PMID: 31442699 DOI: 10.1016/j.foodchem.2019.125370] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2019] [Revised: 06/24/2019] [Accepted: 08/13/2019] [Indexed: 11/28/2022]
Abstract
Four Arabica coffees (Brazil, Colombia, Ethiopia, and Guatemala) yield highly variant odours, attesting to the complexities of coffee aroma that command advanced analytical tools. In this study, their volatiles were extracted using solvent-assisted flavour evaporation (SAFE) and headspace solid-phase microextraction (HS-SPME). Due to matrix complexity, some trace odourants were detected in SAFE extracts by aroma extract dilution analysis (AEDA) but remained difficult to quantify by gas chromatography-mass spectrometry (GC-MS). This prompted the application of low energy electron ionisation (EI) coupled with GC-quadrupole time-of-flight (GC-QTOF). Optimal low EI GC-QTOF parameters (EI energy: 15 eV, acquisition rate: 3 Hz) were applied to achieve improved molecular ion signal intensity and reproducibility (relative standard deviation < 10%) across five compounds, which resulted in good linearity (R2 ≥ 0.999) and lowered detection levels (e.g. 0.025 ± 0.005 ng/mL for 4-hydroxy-5-methyl-3(2H)-furanone). Therefore, this method potentially improves the measurement of trace odourants in complex matrices by increasing specificity and sensitivity.
Collapse
Affiliation(s)
- Aileen Pua
- Food Science and Technology Programme, Department of Chemistry, National University of Singapore, S14 Level 5, Science Drive 2, Singapore 117542, Singapore
| | - Hazel Lau
- Food Science and Technology Programme, Department of Chemistry, National University of Singapore, S14 Level 5, Science Drive 2, Singapore 117542, Singapore
| | - Shao Quan Liu
- Food Science and Technology Programme, Department of Chemistry, National University of Singapore, S14 Level 5, Science Drive 2, Singapore 117542, Singapore.
| | - Lay Peng Tan
- Agilent Technologies Singapore (Sales) Pte Ltd, 1 Yishun Avenue 7, Singapore 768923, Singapore
| | - Rui Min Vivian Goh
- Food Science and Technology Programme, Department of Chemistry, National University of Singapore, S14 Level 5, Science Drive 2, Singapore 117542, Singapore
| | - Benjamin Lassabliere
- Mane SEA PTE LTD, 3 Biopolis Drive, #07-17/18/19 Synapse, Singapore 138623, Singapore
| | - Kwong-Chee Leong
- Mane SEA PTE LTD, 3 Biopolis Drive, #07-17/18/19 Synapse, Singapore 138623, Singapore
| | - Jingcan Sun
- Mane SEA PTE LTD, 3 Biopolis Drive, #07-17/18/19 Synapse, Singapore 138623, Singapore
| | - Maurin Cornuz
- Mane SEA PTE LTD, 3 Biopolis Drive, #07-17/18/19 Synapse, Singapore 138623, Singapore
| | - Bin Yu
- Mane SEA PTE LTD, 3 Biopolis Drive, #07-17/18/19 Synapse, Singapore 138623, Singapore.
| |
Collapse
|
8
|
A systematic study of molecular ion intensity and mass accuracy in low energy electron ionisation using gas chromatography-quadrupole time-of-flight mass spectrometry. Talanta 2019; 199:431-441. [DOI: 10.1016/j.talanta.2019.02.089] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 02/22/2019] [Accepted: 02/26/2019] [Indexed: 11/20/2022]
|
9
|
Potgieter H, de Coning P, Bekker R, Rohwer E, Amirav A. The pre-separation of oxygen containing compounds in oxidised heavy paraffinic fractions and their identification by GC-MS with supersonic molecular beams. JOURNAL OF MASS SPECTROMETRY : JMS 2019; 54:328-341. [PMID: 30720234 DOI: 10.1002/jms.4340] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/23/2018] [Revised: 01/21/2019] [Accepted: 01/28/2019] [Indexed: 06/09/2023]
Abstract
The heavy petroleum fractions produced during refining processes need to be upgraded to useable products to increase their value. Hydrogenated heavy paraffinic fractions can be oxidised to produce high value products that contain a variety of oxygenates. These heavy oxygenated paraffinic fractions need to be characterised to enable the control of oxidation processes and to understand product properties. The accurate identification of the oxygenates present in these fractions by electron ionisation (EI) mass spectrometry is challenging due to the complexity of these heavy fractions. Adding to this challenge is the limited applicability of EI mass spectral libraries due to the absence of molecular ions from the EI mass spectra of many oxygenates. The separation of oxygenates from the complex hydrocarbon matrix prior to high temperature GC-MS (HT-GC-MS) analysis reduces the complexity of these fractions and assists in the accurate identification of these oxygenates. Solid phase extraction (SPE) and supercritical fluid chromatography (SFC) were employed as prefractionation techniques. GC-MS with supersonic molecular beams (SMBs) (also named GC-MS with cold-EI) utilises a SMB interface with which EI is done with vibrationally cold sample compounds in a fly-through ion source (cold-EI) resulting in a substantial increase in the molecular ion signal intensity in the mass spectrum. This greatly enhances the accurate identification of the oxygenates in these fractions. This study investigated the ionisation behaviour of oxygenated compounds using cold-EI. The prefractionation by SPE and SFC and the subsequent analysis with GC-MS with cold-EI were applied to an oxygenated heavy paraffinic fraction.
Collapse
Affiliation(s)
- Hein Potgieter
- Operations and Analytics Department, Group Technology R&T, Sasol, Sasolburg, South Africa
| | - Piet de Coning
- Operations and Analytics Department, Group Technology R&T, Sasol, Sasolburg, South Africa
| | - Riaan Bekker
- Operations and Analytics Department, Group Technology R&T, Sasol, Sasolburg, South Africa
| | - Egmont Rohwer
- Department of Chemistry, University of Pretoria, Pretoria, South Africa
| | - Aviv Amirav
- School of Chemistry, Tel Aviv University, Tel Aviv, Israel
| |
Collapse
|
10
|
Kondyli A, Schrader W. High-resolution GC/MS studies of a light crude oil fraction. JOURNAL OF MASS SPECTROMETRY : JMS 2019; 54:47-54. [PMID: 30378212 DOI: 10.1002/jms.4306] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Revised: 09/18/2018] [Accepted: 10/23/2018] [Indexed: 06/08/2023]
Abstract
The continuous development in analytical instrumentation has brought the newly developed Orbitrap-based gas chromatography / mass spectrometry (GC/MS) instrument into the forefront for the analysis of complex mixtures such as crude oil. Traditional instrumentation usually requires a choice to be made between mass resolving power or an efficient chromatographic separation, which ideally enables the distinction of structural isomers that is not possible by mass spectrometry alone. Now, these features can be combined, thus enabling a deeper understanding of the constituents of volatile samples on a molecular level. Although electron ionization is the most popular ionization method employed in GC/MS analysis, the need for softer ionization methods has led to the utilization of atmospheric pressure ionization sources. The last arrival to this family is the atmospheric pressure photoionization (APPI), which was originally developed for liquid chromatography / mass spectrometry (LC/MS). With a newly developed commercial GC-APPI interface, it is possible to extend the characterization of unknown compounds. Here, first results about the capabilities of the GC/MS instrument under high or low energy EI or APPI are reported on a volatile gas condensate. The use of different ionization energies helps matching the low abundant molecular ions to the structurally important fragment ions. A broad range of compounds from polar to medium polar were successfully detected and complementary information regarding the analyte was obtained.
Collapse
Affiliation(s)
- Aikaterini Kondyli
- Max-Planck Institut für Kohlenforschung, Mass Spectrometry Group, Kaiser-Wilhelm-Platz 1, 45470, Mülheim an der Ruhr, Germany
| | - Wolfgang Schrader
- Max-Planck Institut für Kohlenforschung, Mass Spectrometry Group, Kaiser-Wilhelm-Platz 1, 45470, Mülheim an der Ruhr, Germany
| |
Collapse
|
11
|
Tsizin S, Seemann B, Alon T, Amirav A. Second hydrogen atom abstraction by molecular ions. JOURNAL OF MASS SPECTROMETRY : JMS 2017; 52:638-642. [PMID: 28685904 DOI: 10.1002/jms.3966] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Revised: 06/25/2017] [Accepted: 07/03/2017] [Indexed: 06/07/2023]
Abstract
We report the observation of a new physical phenomenon of the addition of 2 hydrogen atoms to molecular ions thus forming [M + 2H]+ ions. We demonstrate such second hydrogen atom abstraction onto the molecular ions of pentaerythritol and trinitrotoluene (TNT). We used both gas chromatography mass spectrometry (GC-MS) with supersonic molecular beam (SMB) with methanol added into its make-up gas and electron ionization (EI) liquid chromatography mass spectrometry (LC-MS) with SMB with methanol as the LC solvent. We found that the formation of methanol clusters resulted upon EI in the formation of dominant protonated pentaerythritol ion at m/z = 137 plus about 70% relative abundance of pentaerythritol molecular ion with 2 additional hydrogen atoms at m/z = 138 which is well above the 5.7% natural C13 isotope abundance of protonated pentaerythritol. Similarly, we found an abundant protonated TNT ion at m/z = 228 and a similar abundance of TNT molecular ion with 2 additional hydrogen atoms at m/z = 229. Upon the use of deuterated methanol (CD3 OD) as the solvent, we observed an abundant m/z = 231 (M + 2D)+ of TNT with 2 deuterium atoms. We found such abundant second hydrogen atom abstraction with butylglycolate and at low abundances in dioctylphthalate, Vitamin K3, phenazine, and RDX. At this time, we are unable to report the magnitude and frequency of occurrence of this phenomenon in standard electrospray LC-MS. This observation could have important implications on the provision of elemental formula from mass spectra that are involved with protonated molecules. Accordingly, while accurate mass measurements can serve for the generation of elemental formula, their further support and improvement via isotope abundance analysis are questionable. Consequently, if a given compound can be analyzed by both GC-MS and LC-MS, its GC-MS analysis can be superior for the provision of accurate elemental formulae if its EI mass spectrum exhibits abundant molecular ions such as with GC-MS with SMB (also known as cold EI).
Collapse
Affiliation(s)
- Svetlana Tsizin
- School of Chemistry, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Boaz Seemann
- School of Chemistry, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Tal Alon
- School of Chemistry, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Aviv Amirav
- School of Chemistry, Tel Aviv University, Tel Aviv, 69978, Israel
| |
Collapse
|