Liquid chromatography-tandem mass spectrometry determination of bumetanide in human plasma and application to a clinical pharmacokinetic study

Determining a drug's bioavailability and bioequivalence is important for developing and approving a drug product. The procedure supports applications for generic drug products and novel therapeutic substances, makes important decisions regarding safety and efficacy, and measures a drug's concentration in biological matrices. This study aimed to develop and validate a specific, simple, sensitive, and accurate method using liquid chromatography-tandem mass spectrometry (LC-MS) for measuring bumetanide (BUM) in human plasma. Chromatographic separation was achieved using a Hypurity C18 column (4.6 × 50 mm, 5 μm) under isocratic conditions, and LC-MS detected positive ionization acquisition modes. Protonated precursor to product ion transitions were observed at m/z 365.08 → 240.10 and 370.04 → 244.52 for BUM and internal standard, respectively. The linear range of BUM in plasma samples was 3.490-401.192 ng/mL. The inter-precision value ranged from 1.76% to 4.75%. The inter-accuracy value ranged from 96.46% to 99.95%. The method was adequately validated per the U.S. Food and Drug Administration guidelines, and the results were within permissible bounds. The Cmax and Tmax values were ~53.097 ± 13.537 ng/mL and 1.25 (0.67-5.00) h, respectively. The new approach showed satisfactory results for studying BUM in human plasma with potential use in pharmacokinetic and bioequivalence investigations.

Thermosensitive polymer-assisted extraction and purification of fungal laccase from citrus pulp wash effluent

BACKGROUND

This study explores the use of liquid-liquid extraction with thermosensitive polymers for producing laccase (Lac) from Pleurotus sajor-caju. This process leverages liquid waste from the citrus industry, specifically pulp wash. The research delves into extractive fermentation and thermoseparation, both processes being facilitated by a polymer exhibiting a lower critical solution temperature transition.

RESULTS

Key factors considered include the choice of polymer, its concentration, pH, separation temperature, and the behavior of the polymer-rich phase post-extractive fermentation concerning the lower critical solution temperature. Notably, under conditions of 45% by weight of Pluronic L-61 and pH 5.0 at 25 °C, the Lac resulted in an enhancement in the purification factor of 28.4-fold, compared with the Lac obtained directly from the fermentation process on the eighth day. There was an 83.6% recovery of the Lac enzyme in the bottom phase of the system. Additionally, the unique properties of Pluronic L-61, which can induce phase separation and also allow for thermoseparation, led to a secondary fraction (aqueous solution) of Lac with purification factor of 2.1 ± 0.1-fold (at 32 ± 0.9 °C and 30 ± 0.3 min without stirring) from the polymeric phase (top phase). Fourier-transform infrared analysis validated the separation data, particularly highlighting the α-helix content in the amide I region (1600-1700 cm-1 ).

CONCLUSION

In summary, the insights from this study pave the way for broader industrial applications of these techniques, underscoring benefits like streamlined process integration, heightened selectivity, and superior separation efficacy. © 2023 Society of Chemical Industry.

Economic simulation of batch and continuous aqueous two-phase purification for viral products

Vaccine manufacturing strategies that lower capital and production costs could improve vaccine access by reducing the cost per dose and encouraging localized manufacturing. Continuous processing is increasingly utilized to drive lower costs in biological manufacturing by requiring fewer capital and operating resources. Aqueous two-phase systems (ATPS) are a liquid-liquid extraction technique that enables continuous processing for viral vectors. To date, no economic comparison between viral vector purifications using traditional methods and ATPS has been published. In this work, economic simulations of traditional chromatography-based virus purification were compared to ATPS-based virus purification for the same product output in both batch and continuous modes. First, the modeling strategy was validated by re-creating a viral subunit manufacturing economic simulation. Then, ATPS capital and operating costs were compared to that of a traditional chromatography purification at multiple scales. At all scales, ATPS purification required less than 10% of the capital expenditure compared to chromatography-based purification. At an 11 kg per year production scale, the ATPS production costs were 50% less than purification with chromatography. Other chromatography configurations were explored, and may provide a production cost benefit to ATPS, but the purity and recovery were not experimentally verified. Batch and continuous ATPS were similar in capital and production costs. However, manual price adjustments suggest that continuous ATPS plant-building costs could be less than half that of batch ATPS at the 11 kg per year production scale. These simulations show the significant reduction in manufacturing costs that ATPS-based purification could deliver to the vaccine industry.

Application of Liquid-Liquid Extraction for N-terminal Myristoylation Proteomics

Proteins can be modified by lipids in various ways, for example, by myristoylation, palmitoylation, farnesylation, and geranylgeranylation-these processes are collectively referred to as lipidation. Current chemical proteomics using alkyne lipids has enabled the identification of lipidated protein candidates but does not identify endogenous lipidation sites and is not readily applicable to in vivo systems. Here, we introduce a proteomic methodology for global analysis of endogenous protein N-terminal myristoylation sites that combines liquid-liquid extraction of hydrophobic lipidated peptides with liquid chromatography-tandem mass spectrometry using a gradient program of acetonitrile in the high concentration range. We applied this method to explore myristoylation sites in HeLa cells and identified a total of 75 protein N-terminal myristoylation sites, which is more than the number of high-confidence myristoylated proteins identified by myristic acid analog-based chemical proteomics. Isolation of myristoylated peptides from HeLa digests prepared with different proteases enabled the identification of different myristoylated sites, extending the coverage of N-myristoylome. Finally, we analyzed in vivo myristoylation sites in mouse tissues and found that the lipidation profile is tissue-specific. This simple method (not requiring chemical labeling or affinity purification) should be a promising tool for global profiling of protein N-terminal myristoylation.

Optimising a urinary extraction method for non-targeted GC-MS metabolomics

Urine is ideal for non-targeted metabolomics, providing valuable insights into normal and pathological cellular processes. Optimal extraction is critical since non-targeted metabolomics aims to analyse various compound classes. Here, we optimised a low-volume urine preparation procedure for non-targeted GC-MS. Five extraction methods (four organic acid [OA] extraction variations and a "direct analysis" [DA] approach) were assessed based on repeatability, metabolome coverage, and metabolite recovery. The DA method exhibited superior repeatability, and achieved the highest metabolome coverage, detecting 91 unique metabolites from multiple compound classes comparatively. Conversely, OA methods may not be suitable for all non-targeted metabolomics applications due to their bias toward a specific compound class. In accordance, the OA methods demonstrated limitations, with lower compound recovery and a higher percentage of undetected compounds. The DA method was further improved by incorporating an additional drying step between two-step derivatization but did not benefit from urease sample pre-treatment. Overall, this study establishes an improved low-volume urine preparation approach for future non-targeted urine metabolomics applications using GC-MS. Our findings contribute to advancing the field of metabolomics and enable efficient, comprehensive analysis of urinary metabolites, which could facilitate more accurate disease diagnosis or biomarker discovery.

Sample preparation for planar chromatography

High-performance thin-layer chromatography has favorable properties for high-throughput separations with a high matrix tolerance. Sample preparation, however, is sometimes required to control specific matrix interferences and to enhance the detectability of target compounds. Trends in contemporary applications have shifted from absorbance and fluorescence detection to methods employing bioassays and mass spectrometry. Traditional methods (shake-flask, heat at reflux, Soxhlet, and hydrodistillation) are being challenged by automated instrumental approaches (ultrasound-assisted and microwave-assisted solvent extraction, pressurized liquid extraction, and supercritical fluid extraction) and the quick, easy cheap, efficient, rugged, and safe extraction method for faster and streamlined sample processing. Liquid-liquid extraction remains the most widely used approach for sample clean-up with increasing competition from solid-phase extraction. On-layer sample, clean-up by planar solid-phase extraction is increasingly used for complex samples and in combination with heart-cut multimodal systems. The automated spray-on sample applicator, the elution head interface, biological detection of target and non-target compounds, and straightforward mass spectrometric detection are highlighted as the main factors directing current interest toward faster and simpler sample workflows, analysis of more complex samples, and the determination of minor contaminants requiring high concentration factors.

Miniaturization and Automation Protocol of a Urinary Organic Acid Liquid-Liquid Extraction Method on GC-MS

The aim of this study was to improve the extraction method for urinary organic acids by miniaturizing and automating the process. Currently, manual extraction methods are commonly used, which can be time-consuming and lead to variations in test results. To address these issues, we reassessed and miniaturized the in-house extraction method, reducing the number of steps and the sample-to-solvent volumes required. The evaluated miniaturized method was translated into an automated extraction procedure on a MicroLab (ML) Star (Hamilton Technologies) liquid handler. This was then validated using samples obtained from the ERNDIM External Quality Assurance program. The organic acid extraction method was successfully miniaturized and automated using the Autosampler robot. The linear range for most of the thirteen standard analytes fell between 0 to 300 mg/L in spiked synthetic urine, with low (50 mg/L), medium (100 mg/L), and high (500 mg/L) levels. The correlation coefficient (r) for most analytes was >0.99, indicating a strong relationship between the measured values. Furthermore, the automated extraction method demonstrated acceptable precision, as most organic acids had coefficients of variation (CVs) below 20%. In conclusion, the automated extraction method provided comparable or even superior results compared to the current in-house method. It has the potential to reduce solvent volumes used during extraction, increase sample throughput, and minimize variability and random errors in routine diagnostic settings.

Ionic Liquids for the Chemical Recycling of Polymeric Materials and Control of Their Solubility

Plastics are wonderful materials that have modernized our daily life; however, importance of effective recycling of plastics is gradually recognized widely. In this account, we describe our discovery of new and efficient methods for the chemical recycling of plastics using ionic liquids (ILs). Since the chemical recycling usually requires high temperature conditions to breakdown chemical bonds in polymeric materials, we thought that less-flammability and non-volatility of ionic liquids are the most suitable physical properties for this purpose. Ionic liquids successfully depolymerized polyamides and unsaturated polyesters smoothly and corresponding monomeric materials were obtained in good yields. To the best of our knowledge, this was the first use of Ionic liquids for such reactions. However, we encountered another difficult problem-separation. To solve the problem, we developed solubility-switchable ionic liquids, a new type of ionic liquids in which solubility is readily changed using the chemistry of protective groups. Conversion between hydrophilic and lipophilic forms was readily achieved using a simple chemical treatment under mild conditions, and the complete separation of products was achieved by liquid-liquid-extraction. The robustness of either form unlocks their wide use as reaction solvents.

Simple Method for the Determination of THC and THC-COOH in Human Postmortem Blood Samples by Gas Chromatography-Mass Spectrometry

A simple and sensitive analytical method was developed for qualitative and quantitative analysis of Δ9-tetrahydrocannabinol (Δ9-THC) and its metabolite 11-nor-Δ9-tetrahydrocannabinol-carboxylic acid (Δ9-THC-COOH) in human postmortem blood using gas chromatography/mass spectrometry (GC-MS) in selected ion monitoring (SIM) mode. The method involved a liquid-liquid extraction in two steps, one for Δ9-THC and a second one for Δ9-THC-COOH. The first extract was analyzed using Δ9-THC-D3 as internal standard. The second extract was derivatized and analyzed using Δ9-THC-COOH-D3 as internal standard. The method was shown to be very simple, rapid, and sensitive. The method was validated for the two compounds, including linearity (range 0.05-1.5 µg/mL for Δ9-THC and 0.08-1.5 µg/mL for Δ9-THC-COOH), and the main precision parameters. It was linear for both analytes, with quadratic regression of calibration curves always higher than 0.99. The coefficients of variation were less than 15%. Extraction recoveries were superior to 80% for both compounds. The developed method was used to analyze 41 real plasma samples obtained from the Forensic Toxicology Service of the Institute of Forensic Sciences of Santiago de Compostela (Spain) from cases in which the use of cannabis was involved, demonstrating the usefulness of the proposed method.

Nanoliter Scale Parallel Liquid-Liquid Extraction for High-Throughput Purification on a Droplet Microarray

In the current drug discovery process, the synthesis of compound libraries is separated from biological screenings both conceptually and technologically. One of the reasons is that parallel on-chip high-throughput purification of synthesized compounds is still a major challenge. Here, on-chip miniaturized high-throughput liquid-liquid extraction in volumes down to 150 nL with efficiency comparable to or better than large-scale extraction utilizing separation funnels is demonstrated. The method is based on automated and programmable merging of arrays of aqueous nanoliter droplets with organic droplets. Multi-step extraction performed simultaneously or with changing conditions as well as handling of femtomoles of compounds are demonstrated. In addition, the extraction efficiency is analyzed with a fast optical readout as well as matrix-assisted laser desorption ionization-mass spectrometry on-chip detection. The new massively parallel and miniaturized purification method adds another important tool to the chemBIOS concept combining chemical combinatorial synthesis with biological screenings on the same miniaturized droplet microarray platform, which will be essential to accelerate drug discovery.

[Study of the possibility of emtricitabine extraction from biomaterial]

THE AIM OF THE STUDY

Is to investigate the opportunity of emtricitabine extraction from biomaterial and to develop method of emtricitabine chemicotoxicological analysis while acute poisoning. This research represents the methods of emtricitabine isolation from urine, plasma and liver samples (rats of Wistar line weighing 180 g) using liquid-liquid extraction. The identification and quantitation methods of emtricitabine in extractions by thin-layer chromatography, ultraviolet spectrophotometry and high-performance liquid chromatography methods were described. The emtricitabine was found extracted from urine with a therapeutic dose of 6.65±2.21 µg/ml and a toxic dose 35.81±1.05 µg/ml, from plasma with a therapeutic dose of 2.91±0.19 µg/ml and a toxic dose of 16.88±0.90 µg/ml.

On chip microfluidic separation of cyclotides

Cyclotides as a cyclic peptide produced by different groups of plants have been a very attractive field of research due to their exceptional properties in biological activities and drug design applications. The importance of cyclotides as new biological activities from nature caused to attract researchers to develop new separation systems. Recent growth and development on chip-based technology for separation and bioassay especially for anticancer having sparklingly advantages comparison with common traditional methods. In this study, the microfluidic separation of Vigno 1-5 cyclotides extracted from Viola ignobilis by using polar and nonpolar forces as a liquid-liquid interaction was investigated through modified microfluidic chips and then the results were compared with a traditional counterpart technique of high-performance liquid chromatography (HPLC). The traditional process of separating cyclotides from plants is a costly and time-consuming procedure. The scientific novelty of this study is to accelerate the separation of cyclotides using modified microfluidic chips with low cost and high efficiency. The results revealed that a novel and simple microfluidic chip concept is an effective approach for separating the Vigno groups in the violet extract. We believe that the concept could potentially be utilized for further drug development process especially for anticancer studies by coupling bioassay chips as online procedures via reducing in time and cost compared with traditional offline methods.

Bioanalysis of Trifluoperazine in human plasma by LC-MS/MS: Application to disposition kinetics

A sensitive, selective and rapid bioanalytical method using liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been developed for the quantification of Trifluoperazine in human plasma. Trifluoperazine-D₈ was used as the internal standard and the extraction from human plasma was performed by liquid-liquid extraction technique using tertiary butyl methyl ether as the solvent. Chromatographic separation was carried out on Zodiac C₁₈ column (50 x 4.6 mm, 3 μm) employing a mixture of acetonitrile, methanol and 5mM ammonium bicarbonate buffer in water (85:10:5, v/v/v) at a flow rate of 0.55 mL/min. The linearity was established within the concentration range of 5-1250 pg/mL with r² >0.99. Results of all the validation parameters as per USFDA guidelines were within the acceptance limits. Pharmacokinetics of Trifluoperazine after oral administration of syrup of 1 mg dose under fasting conditions was performed by successful application of the present method.

Efficient Electrocatalyst Nanoparticles from Upcycled Class II Capacitors

To move away from fossil fuels, the electrochemical reaction plays a critical role in renewable energy sources and devices. The anodic oxygen evolution reaction (OER) is always coupled with these reactions in devices but suffers from large energy barriers. Thus, it is important for developing efficient OER catalysts with low overpotential. On the other hand, there are large amounts of metals in electronic waste (E-waste), especially various transition metals that are promising alternatives for catalyzing OER. Hence, this work, which focuses on upcycling Class II BaTiO₃ Multilayer Ceramic Capacitors, of which two trillion were produced in 2011 alone. We achieved this by first using a green solvent extraction method that combined the ionic liquid Aliquat^® 336 and hydrochloride acid to recover a mixed solution of Ni, Fe and Cu cations, and then using such a solution to synthesize high potential catalysts NiFe hydroxide and NiCu hydroxide for OER. NiFe-hydroxide has been demonstrated to have faster OER kinetics than the NiCu-hydroxide and commercial c-RuO₂. In addition, it showed promising results after the chronopotentiometry tests that outperform c-RuO₂.

Bioanalytical method for estimation of procyclidine in human plasma using liquid chromatography-tandem mass spectrometry: Application to pharmacokinetic study

A rapid, selective and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed and validated for quantification of procyclidine hydrochloride in human plasma using Procyclidine D11 hydrochloride as internal standard. Liquid-liquid extraction technique with methyl tertiary butyl ether was used for the extraction of plasma samples. Chromatographic separation of the analyte and the internal standard from the endogenous components was done on Zodiac C₁₈ column (50 × 4.6 mm, 5 µm) using a mixture of methanol and 0.1% formic acid in water (70:30, v/v) as mobile phase at a flow rate of 1 mL/min with the run time of 2 min. The detection of the eluents was done using multiple reaction monitoring (MRM) in positive ion mode. Linearity of the method was established in the concentration range of 0.5 to 120 ng/mL. Full validation of the method was done as per USFDA guidelines and the results were well within the acceptance limits. The successful application of the method was done on healthy human subjects under fasting conditions, proving it to be used for bioequivalence and bioavailability (BA/BE) studies of procyclidine.

A Sensitive LC-MS/MS Method for the Simultaneous Determination of Two Thia-Analogous Indirubin N-Glycosides and Indirubin-3'-Monoxime in Plasma and Cell Culture Medium

Indirubin was identified as an active component of Danggui Longhui Wan, an herbal mixture used in traditional Chinese medicine, and showed anticancer activity in clinical trials in patients with chronic leukemia. Investigations on the mechanisms of antitumor action of indirubins have mainly focused on the indirubin derivative indirubin-3'-monoxime (I3M). Meanwhile, antiproliferative and cytotoxic properties on cancer cells have also been demonstrated for several synthetic indirubin N-glycosides. In the present study, we demonstrate cytotoxic activity of the thia-analogous indirubin N-glycosides KD87 (3-[3'-oxo-benzo[b]thiophen-2'-(Z)-ylidene]-1-(β-d-glucopyranosyl)-oxindole) and KD85 (3-[3'-oxo-benzo[b]thiophen-2'-(Z)-ylidene]-1-(β-d-mannopyranosyl)-oxindole) against melanoma and squamous cell carcinoma cells as well as lung cancer and glioblastoma cells. The advanced state of preclinical studies on the effects of indirubins conducted to date underscores the need for pharmacokinetic data from cellular, animal, and human studies for which reliable quantification is required. Therefore, a sensitive liquid chromatography-tandem mass spectrometric (LC-MS/MS) method was developed and validated for the simultaneous measurement of KD87, KD85, and I3M in plasma and cell culture medium. Experimental conditions for sample preparation were optimized for human plasma protein precipitation and liquid-liquid extraction from plasma and cell culture medium. The methods were successfully validated in accordance with the U.S. Food and Drug Administration Bioanalytical Method Validation and evaluated for selectivity, sensitivity, matrix effect, recovery, carryover, calibration curve linearity, accuracy, precision, and stability. The applicability of the methods was demonstrated by the determination of KD87 in mouse plasma after prior intraperitoneal administration to mice.

Remarkable enantioselectivity enhancement of the extractors with nonaxial chirality in liquid-liquid extraction of underivatized amino acids by introducing t-butyl group

A class of carbonyl extractors, (R)-3, (R)-4, and (R)-5, with nonaxial chirality containing asymmetric carbons has been synthesized and studied for their efficiencies in enantioselective liquid-liquid extraction for underivatized amino acids. The bulky t-butyl ketone extractors, (R)-4 and (R)-5, showed the stereoselectivities ranging 5.4-9.4 of l/d ratio much better than those of the aldehyde extractor, (R)-3, ranging 2.4-5.2. The imine formation rates and yields of the t-butyl ketones were not significantly affected by their bulkiness and even in the absence of resonance-assisted hydrogen bond. This work confirms that a bulky t-butyl ketone can be a good choice in the development of an extractor not only with axial chirality but also with nonaxial chirality for the enantioselective extraction of unprotected amino acids.

[Determination of abacavir in biological objects for the purpose of chemical and toxicological analysis]

Purpose - to develop a technique for isolating abacavir, as well as its detection and quantification in biological objects. Extraction of abacavir from centrifuges was carried out with chloroform at pH 8 in the presence of an electrolyte saturated solution of (NH₄)₂SO₄ once for 3 minutes. The determination of abacavir in extracts from urine, saliva and liver was carried out by thin-layer chromatography in the system of ethyl acetate: trichloromethane: ammonia, a concentrated solution of 25% (17:4:1) ascending method, UV spectrophotometry in a medium of hydrochloric acid 0.1 M, where the absorption spectrum abacavir is characterized by an absorption maximum at a wavelength of 297±1 nm, high performance liquid chromatography, during which one peak with a retention time of 9.5 min was observed on the chromatogram of a standard sample, which coincided with the retention time of abacavir obtained after extraction from biological objects.

[Mathematical planning of the liquid-liquid extraction procedure: a forensic chemical study of verapamil in blood]

The objective of the study is to determine the optimal conditions for blood sample preparation by liquid-liquid extraction using mathematical planning of the experiment by the example of forensic chemical study of verapamil. Evaluation of verapamil recovery from blood samples was performed according to the scheme of multivariate three-level experimental planning using the Box-Behnken design. The effect of aqueous phase pH, the ratio of chloroform to n-butanol in the extraction agent, extraction and centrifugation time, addition of sodium chloride, and the ratio of sample and extraction agent volumes on the recovery was studied. The algorithm using mathematical planning and development of liquid-liquid extraction model of target analyte can be recommended for analysis procedure optimization in forensic chemistry.

Quantitative analysis of fragrance allergens in various matrixes of cosmetics by liquid-liquid extraction and GC-MS

Fragrances are the most common chemicals in cosmetics to which people expose every day. However, the unwanted allergic reactions such as contact dermatitis caused by direct contact with fragrances may happen. In Directive 2003/15/EC of the EU, cosmetic product containing one or more of 26 fragrance allergens must be declared on the package label. In addition, commission regulation (EU) 2017/1410 amending Annexes II and III of cosmetic regulation 1223/2009 restricted fragrance chemical of methyl eugenol, and prohibited Lyral, atranol, chloroatranol to be used in cosmetic. In this study, an efficient and sensitive GC-MS method for 3 banned fragrances, 26 fragrance allergens along with restricted methyl eugenol in cosmetics was established. Sample preparation by liquid-liquid extraction was developed by testing various solvent systems to simplify traditional complex extraction methodologies. Validation of the proposed method showed good linearities in a wide concentration ranges of 0.1-10 μg/mL. The intra-day and inter-day recoveries were between 84.4 and 119% with coefficient of variation (CV) below 13.5%. The limit of quantifications (LOQs) of 27 fragrance allergens were in the range of 2-20 μg/g. A surveillance study consisted with 82 cosmetics was conducted, among which 31 products claimed fragrance-free. The results showed some fragrance-free claims were false. In the other hand, there were seven cosmetics labeled containing Lyral, but only four were detected. The top fragrance allergens detected in the samples were linalool, limonene, and geraniol. The analysis of fragrance allergens in cosmetics indicated that potential contact allergy related to these products should be considered, even though some fragrance allergens were from natural extracts, such as oak moss absolute.

Determination of quetiapine and its metabolites in plasma by field-enhanced sample stacking

Quetiapine is an atypical antipsychotic drug that can be used to treat mental disorders, including schizophrenia, bipolar disorder and Alzheimer's disease. Quetiapine is mainly converted into the active metabolites of norquetiapine and 7-hydroxyquetiapine by the liver enzymes CYP3A4 and CYP2D6. In this study, liquid-liquid extraction (LLE) was used as a sample pretreatment method to eliminate interferences in plasma. tert-Butyl methyl ether was chosen as the extraction solvent. Field-enhanced sample injection (FESS), an online preconcentration technique, was used to analyze quetiapine and its metabolites norquetiapine and 7-hydroxyquetiapine in plasma. The optimal separation condition was 120 mM phosphate (pH 4.0) containing 0.005% (w/v) polyvinyl pyrrolidone and 40% (v/v) methanol. The methanol plug was 0.3 psi for 6 s, the sample was electrokinetic injection by 10 kV for 60 s at positive polarity, and the separation voltage was set at 26 kV. In this experiment, quetiapine, norquetiapine and 7-hydroxyquetiapine were successfully extracted from plasma by the LLE method and stacking and separated by FESS within 15 min. The limits of detection (S/N = 3) of quetiapine, norquetiapine and 7-hydroxyquetiapine were 0.25 ng/mL, 0.50 ng/mL and 1.00 ng/mL, respectively. The linear ranges of quetiapine, norquetiapine and 7-hydroxyquetiapine were 3-120 ng/mL and the correlation coefficients were 0.999. Compared with that of the traditional capillary zone electrophoresis method, the sensitivity enrichment of analytes was 463-835-fold. The optimal experimental conditions were successfully applied to the analysis of plasma samples from patients taking quetiapine for the treatment of schizophrenia.

Cold-induced phase separation for the simple and reliable extraction of sex hormones for subsequent LC-MS/MS analysis

Sex hormones, including androgens, estrogens, and progestogens, are important biomarkers for various diseases. Quantification of sex hormones is typically conducted by LC-MS/MS. At present, most methods require liquid-liquid extraction or solid phase extraction for sample preparation. However, these pretreatments are prone to compromise LC-MS/MS throughput. To improve on the current standard practices, we investigated cold-induced phase separation for sex hormone extraction. After protein precipitation with acetonitrile and adjusting the solution constitution with water, samples were stored at −30°C for 10 min to generate two distinct phases: an acetonitrile-rich layer on top of a water-rich layer. During this process, the hydrophobic sex hormones spontaneously separate into the upper layer. This simple and reliable cold-induced phase separation-based LC-MS/MS methodology was used here to simultaneously detect estrone, estradiol, estriol, testosterone, androstenedione, dehydroepiandrosterone, progesterone, and 17-hydroxyprogesterone in serum. Validation of this method indicated satisfactory performance, including acceptable linearity, accuracy, precision, and tractability. Compared with the mainstream liquid-liquid extraction-based method, this new method exhibits significant progress in throughput, which shortens the time cost of sample preparation from 90 to 40 min. We propose that this method can be an excellent alternative for sex hormone analysis in routine clinical laboratories.

A Downstream Processing Cascade for Separation of Caproic and Caprylic Acid from Maize Silage-Based Fermentation Broth

Production of caproic and caprylic acid through anaerobic fermentation of crops or residual and waste biomass has been regarded as an alternative to the conventional ways, where plant oils and animal fats are mostly used. The downstream processing of the fermentation broth is a particular challenge since the broth has a highly complex composition and low concentrations of the target products. In this study, the proof-of-principle for a separation cascade for caproic (C6) and caprylic acid (C8) produced in a maize silage-based fermentation process was demonstrated. For clarification of the fermentation broth, a filter press and a ceramic ultrafiltration membrane was used to remove coarse solids and to separate suspended particles and macromolecules from the fermentation broth, respectively. With both techniques, the dry matter content was reduced from 6.8 to 2.3% and a particle-free product solution was obtained. Subsequently, the carboxylic acids were extracted with oleyl alcohol by liquid-liquid extraction with an extraction efficiency of 85% for C6 and 97% for C8. Over the whole cascade, 58% of caproic acid and 66% of caprylic acid were recovered from the fermentation broth into the extract. Among all separation steps, solid-liquid separation with the filter press caused the major part of the product loss of 21% of each carboxylic acid. By using separation equipment with a better solid separation efficiency such as decanter centrifuges or belt filter presses this loss could be minimized.

Long-Term Continuous Extraction of Medium-Chain Carboxylates by Pertraction With Submerged Hollow-Fiber Membranes

Medium-chain carboxylic acids (MCCAs), which can be generated from organic waste and agro-industrial side streams through microbial chain elongation, are valuable chemicals with numerous industrial applications. Membrane-based liquid-liquid extraction (pertraction) as a downstream separation process to extract MCCAs has been applied successfully. Here, a novel pertraction system with submerged hollow-fiber membranes in the fermentation bioreactor was applied to increase the MCCA extraction rate and reduce the footprint. The highest average surface-corrected MCCA extraction rate of 655.2 ± 86.4 mmol C m⁻² d⁻¹ was obtained, which was higher than any other previous reports, albeit the relatively small surface area removed only 11.6% of the introduced carbon via pertraction. This submerged extraction system was able to continuously extract MCCAs with a high extraction rate for more than 8 months. The average extraction rate of MCCA by internal membrane was 3.0- to 4.7-fold higher than the external pertraction (traditional pertraction) in the same bioreactor. A broth upflow velocity of 7.6 m h⁻¹ was more efficient to extract MCCAs when compared to periodic biogas recirculation operation as a means to prevent membrane fouling. An even higher broth upflow velocity of 40.5 m h⁻¹ resulted in a significant increase in methane production, losing more than 30% of carbon conversion to methane due to a loss of H₂, and a subsequent drop in the H₂ partial pressure. This resulted in the shift from a microbial community with chain elongators as the key functional group to methanogens, because the drop in H₂ partial pressure led to thermodynamic conditions that oxidizes ethanol and carboxylic acids to acetate and H₂ with methanogens as the syntrophic partner. Thus, operators of chain elongating systems should monitor the H₂ partial pressure when changes in operating conditions are made.

[Determination of four bisphenol environmental hormone residues in infant serum by liquid chromatography-tandem mass spectrometry]

Bisphenols are important industrial raw materials that are widely used to produce plastic bottles (feeding bottles), infant cups, and food and beverage (milk powder) cans. Because of the estrogen-like effect of bisphenols, even low-dose intake of these compounds by trace migration affects normal hormone levels in the human body. Therefore, it is imperative to develop a rapid, accurate, and highly sensitive method for the determination of bisphenols in serum. In this study, methyl tert-butyl ether (MTBE) was used as the extraction solvent, and the liquid-liquid extraction pretreatment method was used for sample processing. A high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method was established for the simultaneous determination of bisphenol A (BPA), bisphenol B (BPB), bisphenol F (BPF), and bisphenol S (BPS) at trace levels in infant serum. The important parameters affecting the extraction efficiency, such as the extraction solvent, extraction time, and extraction solvent volume for the four bisphenol environmental hormones were optimized. Serum samples were extracted by MTBE at 40℃ for 15 min. The target compounds were separated on a Waters ACQUITY UPLC BEH C18 column (50 mm×2.1 mm, 1.7 μm) using ultrapure water and methanol solution containing 0.5 mmol/L ammonium acetate as the mobile phases, with gradient elution at a flow rate of 0.2 mL/min. Finally, the analytes were analyzed by HPLC-MS/MS in the negative ion mode. BPA, BPB, and BPS showed good linearity in the range of 0.25-100 μg/L, while BPF showed good linearity in the range of 1-100 μg/L. The correlation coefficients were 0.9929-0.9959, and the limits of detection for BPA, BPB, BPS, and BPF were 0.05, 0.05, 0.05, 0.5 μg/L, respectively. At the three spiked levels (5, 20, 100 μg/L), the average recoveries of BPA, BPB, BPS, and BPF ranged from 84.56% to 104.43%, and the relative standard deviations were less than 10%. The proposed method was successfully applied to the determination of bisphenol contents in 150 infant serum samples. BPA was detected in most serum samples, and the detection rates in the serum of boys and girls were 90.67% and 89.33%, respectively. The detection rates of BPF in the serum of boys and girls were 6.67% and 1.33%, respectively; the corresponding values for BPS were 5.33% and 16.00%. BPB was not detected. The proposed method has the advantages of simple operation, good recovery, and high precision, and it is suitable for the simultaneous determination of the four bisphenol environmental hormones in infant serum.

Development and Optimisation of Solid-Phase Extraction of Extractable and Bound Phenolic Acids in Spelt (Triticum spelta L.) Seeds

A solid-phase extraction (SPE) technique was developed and optimised for isolation and concentration of extractable and bound phenolic acids from germinated spelt seeds, for analysis by liquid chromatography–mass spectrometry. Samples initially underwent solvent extraction under different conditions to maximise the yield of phenolic antioxidants. Optimal extraction conditions for extractable phenolics were absolute methanol as solvent, sample-to-methanol ratio 1:9, and reconstitution in non-acidified water. The bound phenolics were extracted from sample pellets using hydrolysis with 2 M NaOH, acidification of the hydrolysate with formic acid, and simultaneous isolation and purification using Strata X polymeric RP tubes. Compared to liquid-liquid extraction, this direct SPE protocol has significant advantages in terms of higher extraction efficiencies of total and individual phenolics and their antioxidant activities. These data suggest that direct SPE represents a rapid and reliable method for quantitative analysis of both the extractable and the commonly overlooked bound phenolics in Triticum spelta seeds.

Applications of isothermal titration calorimetry in pure and applied research from 2016 to 2020

The last 5 years have seen a series of advances in the application of isothermal titration microcalorimetry (ITC) and interpretation of ITC data. ITC has played an invaluable role in understanding multiprotein complex formation including proteolysis-targeting chimeras (PROTACS), and mitochondrial autophagy receptor Nix interaction with LC3 and GABARAP. It has also helped elucidate complex allosteric communication in protein complexes like trp RNA-binding attenuation protein (TRAP) complex. Advances in kinetics analysis have enabled the calculation of kinetic rate constants from pre-existing ITC data sets. Diverse strategies have also been developed to study enzyme kinetics and enzyme-inhibitor interactions. ITC has also been applied to study small molecule solvent and solute interactions involved in extraction, separation, and purification applications including liquid-liquid separation and extractive distillation. Diverse applications of ITC have been developed from the analysis of protein instability at different temperatures, determination of enzyme kinetics in suspensions of living cells to the adsorption of uremic toxins from aqueous streams.

Steric Hindrance in Metal Coordination Drives the Separation of Pyridine Regioisomers Using Rhodium(II)-Based Metal-Organic Polyhedra

The physicochemical similarity of isomers makes their chemical separation through conventional techniques energy intensive. Herein, we report that, instead of using traditional encapsulation-driven processes, steric hindrance in metal coordination on the outer surface of Rh^II -based metal-organic polyhedra (Rh-MOPs) can be used to separate pyridine-based regioisomers via liquid-liquid extraction. Through molecular dynamics simulations and wet experiments, we discovered that the capacity of pyridines to coordinatively bind to Rh-MOPs is determined by the positions of the pyridine substituents relative to the pyridine nitrogen and is influenced by steric hindrance. Thus, we exploited the differential solubility of bound and non-bound pyridine regioisomers to engineer liquid-liquid self-sorting systems. As a proof of concept, we separated four different equimolecular mixtures of regioisomers, including a mixture of the industrially relevant compounds 2-chloropyridine and 3-chloropyridine, isolating highly pure compounds in all cases.

Development, validation, and application of a simple UPLC-MS/MS method for simultaneous quantification of five traditional antipsychotics in human plasma

A UPLC-MS/MS method was developed to determine the levels of five traditional antipsychotics (APs) (chlorprothixene, perphenazine, fluphenazine, thioridazine, and promethazine) in human plasma with carbamazepine as the internal standard. Samples were extracted using simple liquid-liquid extraction (ethyl acetate/methyl tert-butyl ether, 2:3 v/v); then the analytes were subjected to gradient elution chromatography with a mobile phase composed of 0.1% formic acid in water and acetonitrile. The analytes were separated using a Waters XBridge BEH C₁₈ column (100 × 2.1 mm, 2.5 μm). The linear ranges of chlorprothixene, perphenazine, fluphenazine, thioridazine, and promethazine are 2-250 ng/mL, r > 0.995. The limit of quantitation is 2 ng/mL, and the limit of detection is in the range of 0.1-0.5 ng/mL. The inter-day and intra-day relative standard deviations are less than 10%, and the relative errors are in the range of -5.70 to 7.20%. The recoveries of the five drugs are in the range of 70-109%. The results of methodology verification indicate that this method is simple, economical, sensitive, and suitable for the simultaneous quantification of five traditional APs in human plasma.

Rapid enrichment and separation of two novel minor phenols from Malus hupehensis utilizing liquid-liquid extraction with three-phase solvent system and high-speed counter-current chromatography based on the polarity parameter

For a rapid enrichment and separation of minor components from Malus hupehensis, the selection of suitable solvent system is the great challenge for liquid-liquid extraction with a three-phase solvent system and high-speed counter-current chromatography. According to the concept of "like dissolves like," the similarity of the average polarity between solvent system and target compounds was the significant characteristic of liquid-liquid extraction with a three-phase solvent system and high-speed counter-current chromatography separation. The polarity parameter model provides a way to calculate the polarity of unknown compounds. Under the guidance of the polarity, an efficient enrichment and separation approach was established through liquid-liquid extraction and high-speed counter-current chromatography with solvent systems composed of n-hexane-ethyl acetate-acetonitrile-water (5:3:5:7, v/v), n-hexane-ethyl acetate-methanol-water (1:2:1:2, v/v), respectively. Thus, the total content of minor compounds was increased from 2.6% to 17.2%, and two novel compounds (6´´-O-coumaroyl-2´-O-glucopyranosylphloretin and 3´´´-methoxy-6´´-O-feruloy-2´-glucopyranosylphloretin) were obtained. The discovery of the new dihydrochalcones expanded the structural diversity of compounds produced by the genus Malus. The experimental results demonstrated that compound polarity can be described by the polarity parameter model and is an important reference for investigating optimum solvent systems for liquid-liquid extraction with a three-phase solvent system and high-speed counter-current chromatography.

Automated liquid-liquid extraction of organic compounds from aqueous samples using a multifunction autosampler syringe

Liquid-liquid extraction is one of the most widely used and simplest sample preparation techniques. However, consumption of large volumes of organic solvent and manual handling are two major drawbacks of this technique. A multifunction autosampler syringe is introduced which permits automated liquid-liquid extraction in an enclosed operating environment, with low consumption of organic solvents. The device described herein features a micromixer function in addition to common autosampler syringe features like accurate and precise aspirating and dispensing. To test the functionality of the micromixer syringe, manual extraction of caffeine from a tea infusion and semi-automated extraction of dichloroethane from water were carried out. Excellent recoveries of caffeine from a tea infusion (89% recovery with 1.3% RSD) and dichloroethane from water (107% recovery with 10% RSD) were obtained. Two automated workflows were tested using the micromixer syringe mounted in a laboratory autosampler. Standalone automated micro liquid-liquid extraction was performed for sample preparation of selected polychlorinated biphenyl (PCB) congeners prior to comprehensive two-dimensional gas chromatography - electron capture detection analysis. Extraction of PCBs using the described approach used substantially less solvent than a validated solid-phase extraction approach whilst delivering equivalent results for samples with high-level PCBs. Finally, fully automated extraction and GC-MS analysis of polynuclear aromatic hydrocarbons (PAHs) from water samples was performed. Mean recoveries of extraction for PCB and PAH analysis were > 70% using 4 min automated liquid-liquid extractions.

[Investigation of the distribution of (±)-N-methyl-3-phenyl-3-(para-trifluoromethyl) phenoxypropylamine hydrochloride in the body of warm-blooded animals]

THE AIM OF THE STUDY

Was to investigate the distribution of (±)-N-methyl-3-phenyl-3-(para-trifluoromethyl) phenoxypropylamine hydrochloride (fluoxetine) in the body of warm-blooded animals. For the experiments, Wistar rats were used. Fluoxetine was isolated from animal organs and bio-liquids by liquid-liquid extraction. Thin layer chromatography, UV spectrophotometry, and high performance liquid chromatography were used for identification and quantification. Techniques for isolating fluoxetine from urine, blood, intestinal contents, kidneys, and liver samples using liquid-liquid extraction are presented. Methods for identification and quantitative determination of fluoxetine in extracts by thin layer chromatography, UV spectrophotometry, and high performance liquid chromatography are described. The greatest amount of fluoxetine was found in the kidneys - 12.94±2.18 mg/100 g, the small intestine with contents - 9.50±1.90 mg/100 g and liver - 9.28±1.37 mg/100 g.

First Profile of Phenolic Compounds from Maltese Extra Virgin Olive Oils Using Liquid-Liquid Extraction and Liquid Chromatography-Mass Spectrometry

This study presents the profile of phenolic extracts from different Extra Virgin Olive Oils (EVOOs) from Malta and is the first study that characterizes the phenolic profile of the Maltese EVOOs Bidni (B) and Malti (M) using liquid-liquid extraction (LLE) and Liquid Chromatography-Mass Spectrometry (LC-MS). The total phenolic content (TPC), ortho diphenolic content (TdPC) and flavonoid content (TFC) were determined using the Folin-Ciocalteau assay, the Arnow's assay and the Aluminium Chloride method respectively. Results show that the B variety had the highest TPC, TdPC and TFC. Using LC-MS analysis, over 30 phenolic compounds were identified belonging to different classes of phenolic compounds.

Understanding the Complex Surface Interplay for Extraction: A Molecular Dynamics Study

By means of classical molecular dynamics simulation the interfacial properties of methanol and n‐dodecane, which are two potential candidate solvents for use in non‐aqueous liquid–liquid extraction, were assessed. The question of how the interface changes depending on the concentration of extractant (tri‐n‐butyl phosphate) and salt (LiCl) is addressed. Two different models to represent systems were used to evaluate how LiCl and tri‐n‐butyl phosphate affect mutual miscibility, and how the last‐named behaves depending on the chemical environment. Tri‐n‐butyl phosphate increases the mutual solubility of the solvents, whereas LiCl counteracts it. The extractant was found to be mostly adsorbed on the interface between the solvents, and therefore the structural features of the adsorption were investigated. Adsorption of tri‐n‐butyl phosphate changes depending on its concentration and the presence of LiCl. It exhibits a preferential orientation in which the butyl chains point at the n‐dodecane phase and the phosphate group points at the methanol phase. For high concentrations of tri‐n‐butyl phosphate, its molecular orientation is preserved by diffusion of the excess molecules into both the methanol and n‐dodecane phases. However, LiCl hinders the diffusion into the methanol phase, and thus increases the concentration of tri‐n‐butyl phosphate at the interface and forces a rearrangement with subsequent loss of orientation.

Vitamin D in human serum and adipose tissue after supplementation

BACKGROUND

Serum 25-hydroxyvitamin D [25(OH)D] concentration is an indicator of vitamin D exposure, but it is also influenced by clinical characteristics that affect 25(OH)D production and clearance. Vitamin D is the precursor to 25(OH)D but is analytically challenging to measure in biological specimens.

OBJECTIVES

We aimed to develop and validate a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for quantification of vitamins D3 and D2 in serum and to explore the potential of circulating vitamin D as a biomarker of exposure in supplementation trials.

METHODS

The method was validated using guideline C62-A from the Clinical and Laboratory Standards Institute and was applied in 2 pilot clinical trials of oral vitamin D3 supplementation. Pilot study 1 included 22 adults randomly assigned to placebo or 2000 IU/d. Blood was collected at baseline, 1, 3, 6, and 12 mo. Pilot study 2 included 15 adults randomly assigned to 2000 or 4000 IU/d. Blood and subcutaneous (SUBQ) adipose tissue were collected at baseline and 3 mo.

RESULTS

In study 1, mean change (baseline to 3 mo) in serum vitamin D3 was -0.1 ng/mL in the placebo group and 6.8 ng/mL in the 2000 IU/d group (absolute difference: 6.9; 95% CI: 4.5, 9.3 ng/mL). In study 2, mean change (baseline to 3 mo) in serum vitamin D3 was 10.4 ng/mL in the 2000 IU/d group and 22.2 ng/mL in the 4000 IU/d group (fold difference: 2.15; 95% CI: 1.40, 3.37). Serum and adipose tissue vitamin D3 concentrations were correlated, and the dose-response of vitamin D3 in adipose mirrored that in serum.

CONCLUSIONS

We validated a sensitive, robust, and high-throughput LC-MS/MS method to quantify vitamins D3 and D2 in serum. Serum and SUBQ adipose tissue vitamin D3 concentrations increased proportionally to dose with 3 mo of daily supplementation.These trials were registered at clinicaltrials.gov as NCT00552409 (pilot study 1) and NCT01477034 (pilot study 2).

Design and evaluation of a continuous semipartition bioreactor for in situ liquid-liquid extractive fermentation

Extractive fermentation (or in situ product removal (ISPR)) is an operational method used to combat product inhibition in fermentations. To achieve ISPR, different separation techniques, modes of operation and physical reactor configurations have been proposed. However, the relative paucity of industrial application necessitates continued investigation into reactor systems. This article outlines a bioreactor designed to facilitate in situ product extraction and recovery, through adapting the reaction volume to include a settler and solvent extraction and recycle section. This semipartition bioreactor is proposed as a new mode of operation for continuous liquid-liquid extractive fermentation. The design is demonstrated as a modified bench-top fermentation vessel, initially analysed in terms of fluid dynamic studies, in a model two-liquid phase system. A continuous abiotic simulation of lactic acid (LA) fermentation is then demonstrated. The results show that mixing in the main reaction vessel is unaffected by the inserted settling zone, and that the size of the settling tube effects the maximum volumetric removal rate. In these tests the largest settling tube gave a potential continuous volumetric removal rate of 7.63 ml/min; sufficiently large to allow for continuous product extraction even in a highly productive fermentation. To demonstrate the applicability of the developed reactor, an abiotic simulation of a LA fermentation was performed. LA was added to reactor continuously at a rate of 33ml/h, while continuous in situ extraction removed the LA using 15% trioctylamine in oleyl alcohol. The reactor showed stable LA concentration of 1 g/L, with the balance of the LA successfully extracted and recovered using back extraction. This study demonstrates a potentially useful physical configuration for continuous in situ extraction.

Optimization for Liquid-Liquid Extraction of Cd(II) over Cu(II) Ions from Aqueous Solutions Using Ionic Liquid Aliquat 336 with Tributyl Phosphate

This study investigates the separation of two heavy metals, Cd(II) and Cu(II), from the mixed synthetic feed using a liquid-liquid extraction. The current study uses tri-octyl methylammonium chloride (Aliquat 336) as the extractant (with tributyl phosphate (TBP) as a phase modifier), diluted in toluene, in order to investigate the selective extraction of Cd(II) over Cu(II) ions. We investigate the use of ethylenediaminetetraacetic acid (EDTA) as a masking agent for Cu(II), when added in aqueous feed, for the selective extraction of Cd(II). Five factors that influence the selective extraction of Cd(II) over Cu(II) (the equilibrium pH (pH_eq), Aliquat 336 concentration (Aliquat 336), TBP concentration (TBP), EDTA concentration (EDTA), and organic to aqueous ratio (O:A)) were analyzed. Results from a 2^5–1 fractional factorial design show that Aliquat 336 significantly influenced Cd(II) extraction, whereas EDTA was statistically significant for the antagonistic effect on the E% of Cu(II) in the same system. Moreover, results from optimization experiment showed that the optimum conditions are Aliquat 336 concentration of 99.64 mM and EDTA concentration of 48.86 mM—where 95.89% of Cd(II) was extracted with the least extracted Cu(II) of 0.59%. A second-order model was fitted for optimization of Cd(II) extraction with a R² value of 0.998, and ANOVA results revealed that the model adequately fitted the data at a 5% significance level. Interaction between Aliquat 336 and Cd(II) has been proven via FTIR qualitative analysis, whereas the addition of TBP does not affect the extraction mechanism.

Metabolic profiling of aromatic compounds in cerebrospinal fluid of neurosurgical patients using microextraction by packed sorbent and liquid-liquid extraction with gas chromatography-mass spectrometry analysis

A new approach to the quantitative analysis of aromatic metabolites in cerebrospinal fluid samples of neurosurgical patients based on microextraction by packed sorbent coupled with derivatization and GC-MS was developed. Analytical characteristics such as recoveries (40-90%), limit of detection (0.1-0.3 μm) and limit of quantitation (0.4-0.7 μm) values, accuracy (<±20%), precision (<20%) and linear correlations (R²  ≥ 0.99) over a 0.4-10 μm range of concentrations demonstrated that microextraction by packed sorbent provides results for the quantitative analysis of target compounds comparable with those for liquid-liquid extraction. Similar results were achieved using 40 μl of sample for microextraction by packed sorbent instead of 200 μl for liquid-liquid extraction. Benzoic, 3-phenylpropionic, 3-phenyllactic, 4-hydroxybenzoic, 2-(4-hydroxyphenyl)acetic, homovanillic and 3-(4-hydroxyphenyl)lactic acids were found in cerebrospinal fluid samples (n = 138) of neurosurgical patients in lower concentrations than in serum samples (n = 110) of critically ill patients. Analysis of the cerebrospinal fluid and serum samples taken at the same time from neurosurgical patients (n = 5) revealed similar results for patients without infection and multidirectional results for patients with central nervous system infection. Our preliminary results demonstrate the necessity of further evaluating the aromatic compound profile in cerebrospinal fluid for its subsequent verification for potential diagnostic markers.

Analytical approaches applied to the analysis of apprehended formulations of anabolic androgenic steroids

Anabolic androgenic steroids (AASs) comprise a class of synthetic androgens resulting from chemical modifications of testosterone, known for their illicit consumption, which can result inextensive side effects. Extraction procedures applied to the analysis of their formulations are still limited to a few methodologies, despite the increasing numbers of confiscations of AASs. In this sense, the aims of this work were to evaluate the extraction of active ingredients from formulations of anabolic agents using solid-liquid or liquid-iquid, ultrasonic bath, ultrasonicprobe, and microwave-assisted extraction. The results indicated that the extraction procedures influenced the detected concentration of AASs, as the use of ultrasonic probe and microwave irradiation increased the overall extraction of anabolic agents compared with solid-liquid, liquid-liquid, and ultrasonic bath. Regarding oxymetholone, for instance, the microwave-assisted extraction and ultrasonic probe extracted, respectively, 37.46 ± 1.36 and 35.69 ± 0.98 mg/tablet, while solid-liquid extracted 29.63 ± 0.40 mg/tablet of the activeingredient. Therefore, alternative methods such as microwave-assisted extraction or theultrasonic probe could be used for the analysis of formulations of AASs assisting with the identification of illicit and toxic components.

Identification of Transient Receptor Potential Vanilloid 3 Antagonists from Achillea alpina L. and Separation by Liquid-Liquid-Refining Extraction and High-Speed Counter-Current Chromatography

Bioassay-guided fractionation of the ethanol extract of whole herbs of Achilleaalpina led to the isolation of isochlorogenic acids A and B as transient receptor potential vanilloid 3 (TRPV3) channel antagonists by using a calcium fluorescent assay. The structures were identified by spectroscopic analysis and the inhibitory activities of isochlorogenic acids A and B were confirmed by whole-cell patch clamp recordings of human embryonic kidney 293 (HEK293) cells expressing human TRPV3. Molecular docking results revealed that these two compounds reside in the same active pocket of human TRPV3 channel protein with lower binding energy than the agonist 2-aminoethoxydiphenyl borate (2-APB). High-speed counter-current chromatography (HSCCC) coupled with a liquid-liquid extraction approach was successfully established for the separation of isochlorogenic acids A and B from the whole herbs of A. alpina. Ethyl acetate and n-hexane-ethyl acetate-water (3:3:4 and 1:5:4, v/v/v) were selected as liquid-liquid extraction solvent systems to remove high- and low-polarity impurities in the mixture. Sixty g of ethanol extract was refined by solvent partition to yield 1.7 g of the enriched fraction, of which 480 mg in turn obtained 52.5 mg of isochlorogenic acid B (purity 98.3%) and 37.6 mg isochlorogenic acid A (purity 96.2%) after HSCCC with n-hexane-ethyl acetate-water containing 1% acetic acid (1:4:8, v/v/v).

3D Printing in analytical sample preparation

In the last 5 years, additive manufacturing (three-dimensional printing) has emerged as a highly valuable technology to advance the field of analytical sample preparation. Three-dimensional printing enabled the cost-effective and rapid fabrication of devices for sample preparation, especially in flow-based mode, opening new possibilities for the development of automated analytical methods. Recent advances involve membrane-based three-dimensional printed separation devices fabricated by print-pause-print and multi-material three-dimensional printing, or improved three-dimensional printed holders for solid-phase extraction containing sorbent bead packings, extraction disks, fibers, and magnetic particles. Other recent developments rely on the direct three-dimensional printing of extraction sorbents, the functionalization of commercial three-dimensional printable resins, or the coating of three-dimensional printed devices with functional micro/nanomaterials. In addition, improved devices for liquid-liquid extraction such as extraction chambers, or phase separators are opening new possibilities for analytical method development combined with high-performance liquid chromatography. The present review outlines the current state-of-the-art of three-dimensional printing in analytical sample preparation.

Method Optimization: Analysis of Benzbromarone and Tolfenamic Acid in Citrus Tissues and Soil Using Liquid Chromatography Coupled With Triple-Quadrupole Mass Spectrometry

Herein, an analytical method was developed for extraction and quantification of benzbromarone and tolfenamic acid in citrus and soil matrices using liquid-liquid extraction followed by liquid chromatography-triple quadrupole-tandem mass spectrometry analysis. The compounds were extracted using 0.1% formic acid in 6:4 ethyl acetate and n-hexane solution, and the analytes were separated using a mixture of 0.1% formic acid in ultrapure water and 0.1% formic acid in acetonitrile as mobile phase. A six-point in-matrix calibration curve was constructed providing good linearity with coefficients of determination R ² ≥ 0.98. The limits of detection and quantification for benzbromarone and tolfenamic acid were 3.0 and 10.0 μg/kg in roots, peel, juice, and soil, and 4.0 and 12.0 μg/kg for leaves samples, respectively. The method yielded excellent recoveries between 81.3 and 101.2%, with relative standard deviation ≤9.5% in the matrices. The developed technique provides a simple and sensitive method for the determination of the chemicals and can be applied to agricultural practices.

Development and Validation of Liquid Chromatography-Tandem Mass Spectrometry Method for Simple Analysis of Sumatriptan and its Application in Bioequivalence Study

This work demonstrated a sensitive, selective, and simple liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for quantitation of sumatriptan in human plasma samples. Terazosin was used as an internal standard to minimize the variability during sample processing and detection. Sample cleanup prior to chromatographic analysis was accomplished by liquid-liquid extraction (LLE) with tert-butyl methyl ether (t-BME). The separation was performed on a reversed-phase Symmetry^® C18 column (150 × 4.6 mm i.d., 5 µm) under a gradient mode, using a 0.2% formic acid aqueous solution and acetonitrile at a flow rate of 0.5 mL/min. Sumatriptan (m/z 296.26→251.05) and terazosin (m/z 388.10→290.25) were quantified using a triple quadrupole mass spectrometer, operating in the multiple reaction monitoring (MRM) under the positive ion mode. The method was fully validated following US-FDA and EMA guidelines. The LC-MS/MS assay had a calibration range of 0.5–50.0 ng/mL. The assay was precise and accurate with a between-run precision of <9.51%, and between-run accuracy between −7.27 to 8.30%. The developed method was subsequently applied in the determination of plasma concentration-time profile of a sumatriptan 50-mg tablet following oral administration in healthy volunteers.

[Chemical and toxicological determination of lamivudine in biological substances]

The purpose of the study is to develop a method for detecting, isolating and quantifying lamivudine in biological substances. Lamivudine was isolated by liquid-liquid and solid phase extraction. The conditions for isolating lamivudine (extractant, pH of the medium, electrolyte, time and frequency of extraction) from aqueous solutions were selected and methods were developed for isolating it from biological substances, including urine, saliva and liver, using liquid-liquid and solid phase extraction methods. Qualitative and quantitative analysis of lamivudine in extracts from urine, saliva and liver was performed by thin layer chromatography, UV spectrophotometry and high-performance liquid chromatography. A validation assessment of the developed techniques indicates their suitability for chemical and toxicological analysis of lamivudine.

Automated on-line liquid-liquid extraction in a multisyringe flow injection analysis manifold for migration studies in food-contact materials: analysis of 4,4´-dihydroxybiphenyl

Packaging may represent a source of food contamination, as different organic compounds and degradation compounds may migrate from packaging to foodstuff. For fatty foods, rectified olive oil is the common simulant, which implies time-consuming and laborious liquid-liquid extraction (LLE) procedures to isolate the contaminant(s) from the oil. Here we propose a Multisyringe Flow Injection Analysis manifold to automate this sample treatment, using the monomer 4,4´-dihydroxybiphenyl as the contaminant. The LLE procedure, using water as extractant, was fully automated. After the on-line LLE, the resulting extract was pumped through a fluorescence detector, inside which a flow-cell filled with C₁₈ silica gel solid support was placed. The analyte was pre-concentrated on the solid support (in which the analytical signal was directly recorded), so improving the sensitivity of the system. Under optimum conditions, the method detection limit is 0.05 mg kg^-1, well within the specific migration limit of 6 mg kg^-1. The method developed was compared with the standard CEN test method (off-line LLE and HPLC determination) observing savings in sample and reagents of 90% and a 7-fold increase in sample throughput.

Α Simple Method for the Determination of Lacosamide in Blood by GC-MS

Lacosamide is a functionalized amino acid with antiepileptic function. Therapeutic drug monitoring (TDM) in patients for lacosamide is critical as it allows clinicians to control epileptic seizures. A single liquid-liquid extraction step was applied for the extraction of lacosamide from whole blood samples which were thereafter analyzed by GC-MS. Optimum extraction conditions were selected on the basis of experiments with various solvents at different pHs, indicating ethyl acetate at pH 12 as the most efficient parameters for the extraction of lacosamide. Method exhibited linearity from 2 to 100 μg/mL with R²  = 0.998. Accuracy and precision were evaluated at three concentrations and found to be within acceptable limits. LOD and LOQ were determined at 0.1 and 0.5 μg/mL, respectively. Lacosamide was found to be stable at storage conditions. The developed method was applied successfully in clinical samples and postmortem blood sample from an overdose case.

Matrix-Induced Sugaring-Out: A Simple and Rapid Sample Preparation Method for the Determination of Neonicotinoid Pesticides in Honey

In the present work, we developed a simple and rapid sample preparation method for the determination of neonicotinoid pesticides in honey based on the matrix-induced sugaring-out. Since there is a high concentration of sugars in the honey matrix, the honey samples were mixed directly with acetonitrile (ACN)-water mixture to trigger the phase separation. Analytes were extracted into the upper ACN phase without additional phase separation agents and injected into the HPLC system for the analysis. Parameters of this matrix-induced sugaring-out method were systematically investigated. The optimal protocol involves 2 g honey mixed with 4 mL ACN-water mixture (v/v, 60:40). In addition, this simple sample preparation method was compared with two other ACN-water-based homogenous liquid-liquid extraction methods, including salting-out assisted liquid-liquid extraction and subzero-temperature assisted liquid-liquid extraction. The present method was fully validated, the obtained limits of detection (LODs) and limits of quantification (LOQs) were from 21 to 27 and 70 to 90 μg/kg, respectively. Average recoveries at three spiked levels were in the range of 91.49% to 97.73%. Precision expressed as relative standard deviations (RSDs) in the inter-day and intra-day analysis were all lower than 5%. Finally, the developed method was applied for the analysis of eight honey samples, results showed that none of the target neonicotinoid residues were detected.

A high-throughput LC-MS/MS method for determination of flunarizine in human plasma: Pharmacokinetic study with different doses

A high-throughput and sensitive liquid chromatography-tandem mass spectrometry (LC-MS/MS) method has been developed and validated for the determination of flunarizine in human plasma. Liquid-liquid extraction under acidic conditions was used to extract flunarizine and flunarizine-d8 from 100 μL human plasma. The mean extraction recovery obtained for flunarizine was 98.85% without compromising the sensitivity of the method. The chromatographic separation was performed on Hypersil Gold C₁₈ (50 × 2.1 mm, 3 μm) column using methanol-10 mm ammonium formate, pH 3.0 (90:10, v/v) as the mobile phase. A tandem mass spectrometer (API-5500) equipped with an electrospray ionization source in the positive ion mode was used for detection of flunarizine. Multiple reaction monitoring was selected for quantitation using the transitions, m/z 405.2 → 203.2 for flunarizine and m/z 413.1 → 203.2 for flunarizine-d8. The validated concentration range was established from 0.10 to 100 ng/mL. The accuracy (96.1-103.1%), intra-batch and inter-batch precision (CV ≤ 5.2%) were satisfactory and the drug was stable in human plasma under all tested conditions. The method was used to evaluate the pharmacokinetics of 5 and 10 mg flunarizine tablet formulation in 24 healthy subjects. The pharmacokinetic parameters C_max and AUC were dose-proportional.

Enantioseparation of flurbiprofen enantiomers using chiral ionic liquids by liquid-liquid extraction

Flurbiprofen is a kind of nonsteroidal anti-inflammatory drug, which has been widely used in clinic for treatment of rheumatoid arthritis and osteoarthritis. It has been reported that S-flurbiprofen shows good performance on clinic anti-inflammatory treatment, while R-enantiomer almost has no pharmacological activities. It has important practical values to obtain optically pure S-flurbiprofen. In this work, chiral ionic liquids, which have good structural designability and chiral recognize ability, were selected as the extraction selector by the assistance of quantum chemistry calculations. The distribution behaviors of flurbiprofen enantiomers were investigated in the extraction system, which was composed of organic solvent and aqueous phase containing chiral ionic liquid. The results show that maximum enantioselectivity up to 1.20 was attained at pH 2.0, 25°C using 1,2-dichloroethane as organic solvent, 1-butyl-3-methylimidazole L-tryptophan ([Bmim][L-trp]) as chiral selector. The racemic flurbiprofen initial concentration was 0.2 mmol L^-1 , and [Bmim][L-trp] concentration was 0.02 mol L^-1 . Furthermore, the recycle of chiral ionic liquids has been achieved by reverse extraction process of the aqueous phase with chiral selector, which is significant for industrial application of chiral ionic liquids and scale-up of the extraction process.

[Determination of trichloroaldehyde in drinking water using liquid-liquid extraction and gas chromatography]

OBJECTIVE

To establish a liquid-liquid extraction and gas chromatography method for the determination of trichloroacetaldehyde in drinking water.

METHODS

Chromatography parameters and extraction parameters, such as extraction solvent, salting out reagents, internal standards and pH were tested and selected. Using the optimized parameters, methods validation and comparison with the national standard examination method was also conducted.

RESULTS

Employing the optimized extraction and instrumental analytic parameters, good correlation coefficient was obtained in the linear range of 0.20-20.0 μg/L, with r greater than 0.999. The methods detection limit was 0.030 μg/L. When spiked concentration was 1.0 μg/L for pure water and tap water, the recoveries were 94.8% and 93.7%, respectively, and relative standard deviation was 2.9% and 3.4%, respectively. When spiked concentration was 16.0 μg/L for pure water and tap water, the recoveries were both 101% and relative standard deviation was 1.0% and 1.3%, respectively. Paired samples t test showed that the result obtained with this method were generally lower than that acquired from the national standard examination method.

CONCLUSION

This method is sensitive and accurate, and it is suitable for the determination of trichloroaldehyde in drinking water.