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Deltamethrin, a well-known type 2 synthetic pyrethroid insecticide, is a widespread environmental toxicant. It has potential to accumulate in body fluids and tissues due to its lipophilic characteristics. The immune system is among the most sensitive targets regarding toxicity of environmental pollutants. Various methods are available in the literature to analyze deltamethrin (DLM) concentration in plasma and tissues, but regarding the immune organs, only one gas chromatography–tandem mass spectrometry (GC–MS/MS) method (on spleen tissues) has been reported. In the present investigation, a rapid and sensitive high-performance liquid chromatography (HPLC) method has been developed and validated to determine DLM concentration in plasma, thymus, and spleen using zaleplone as an internal standard. Liquid chromatography (LC) separation is performed on an Agilent Zorbax® C8 column (250 mm × 4.6 mm, i.d., 5 μm) with isocratic elution using a mobile phase consisting of acetonitrile–5 mM KH2PO4 (70:30, v/v) at a flow rate of 1 mL min−1. The lower limit of quantification (LLOQ) for DLM is 10 ng mL−1 (plasma, thymus, and spleen). The method has been validated in terms of establishing linearity, specificity, sensitivity, recovery, accuracy, and precision (intra- and inter-day) and stabilities study. This validated method was successfully applied to a pharmacokinetic and tissue distribution study of DLM in mice.

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A rapid, selective, sensitive, and simple method for simultaneous determination of tigecycline and its epimer in human plasma samples was developed and validated by liquid chromatography–tandem mass spectrometry (LC–MS/MS). Sample preparation involved one-step protein precipitation by adding 0.1% formic acid–methanol and phosphate buffer (PB) solution to the plasma. Chromatographic separation was obtained with XBridge BEH C18 column (3.5 μm, 50 × 4.6 mm) through a 9.5-min gradient mobile phase at the flow rate of 0.6 mL min−1 at 4 °C. The calibration curves were linear over concentration 5.00–2000 ng mL−1 with correlation coefficient greater than 0.998. Intra-batch and inter-batch accuracy of the assay were in the ranges of −2.90% to 3.00%, and the corresponding precision was less than 6.97%. The extraction recovery of tigecycline and its epimer with the current method were 87.2% and 76.9%, respectively. The applied LC–MS/MS method was shown to be sufficiently sensitive and will be suitable for pharmacokinetic studies.

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A fast, reliable, inexpensive, and practical method with a low determination limit and high recovery has been developed for the determination of the marijuana metabolite in routine analysis. THC-COOH in urine was validated using liquid chromatography—tandem mass spectrometry (LC—MS/MS). Before an easy single-step extraction with Toxi-Tubes, basic hydrolysis was performed at 60 °C for 30 min. LC—MS/MS analysis takes 2.5 min for each sample, and the retention time of the analyte is 1.75 min. Specificity, linearity, limit of detection (LOD), limit of quantification (LOQ), accuracy, repeatability, and intermediate precision (inter-day) system suitability parameters were determined in the validation study. The recovery of the extraction method was 88.67 (±5.91). LOD and LOQ values were 1.41 and 5.00 ng mL−1, respectively. The method showed linear response between the values 5.00 and 500.00 ng mL−1. The repeatability was 9.64% (relative standard deviation, RSD%), and the intermediate precisions (RSDR%) were 10.73%, 13.74%, and 8.11% at 10.00, 100.00, and 200.00 ng mL−1 concentration levels, respectively. No statistically significant difference was found in ANOVA analysis, between three consecutive days in intermediate precision study, for 90% confidence level. HorRat values were between 0.34 and 0.61. The method was applied to CEDIA positive samples, obtained from the Trabzon Group Presidency of Turkish Council of Forensic Medicine, successfully.

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Patrinia scabiosaefolia Fisch. (PSF), a well-known traditional Chinese medicine, has been demonstrated to show therapeutic effects on inflammatory bowel disease. In this study, a rapid and sensitive method using ultra-performance liquid chromatography/quadrupole time-of-flight mass spectrometry (UPLC/Q-TOF-MS) was developed for identification of the major constituents in PSF. The separation analysis was performed on Waters Acquity UPLC system, and the accurate mass of molecules and their fragment ions were determined by Q-TOF-MS. Thirty-one constituents, including triterpenoids, iridoids, flavonoids, and organic acids were detected and tentatively deduced on the basis of their element compositions, tandem mass spectrometry (MS/MS) data, and relevant literatures. Twelve constituents were discovered for the first time in PSF. The results demonstrated that hederagenin-type and oleanolic acid-type saponins were the main constituents of PSF. Our work provides a certain foundation for further quantitation of major chemical constituents and in vivo pharmacokinetic studies of PSF. Moreover, the analytical approach developed herein has proven to be generally applicable for profiling the chemical constituents in traditional Chinese medicines (TCMs) and other complicated mixtures.

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Acta Chromatographica
Authors: Su-su Bao, Jian Wen, Teng-hui Liu, Bo-wen Zhang, Chen-chen Wang, and Guo-xin Hu

Olmutinib (Olita™) is an oral third-generation epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) which is used to treat non-small cell lung cancer (NSCLC). A simple, rapid, and sensitive method based on ultra-performance liquid chromatography tandem mass spectrometry (UHPLC–MS/MS) has been developed for the determination of olmutinib. Sample preparation was performed following simple one-step protein precipitation with acetonitrile. Olmutinib and internal standard (dasatinib) were separated on an Eclipse Plus C18 RRHD (2.1 × 50 mm, 1.8 μm) column. The mobile phase consisted of acetonitrile–0.1% formic acid in water with gradient elution. A total run time of 1.7 min was achieved. Detection was performed on a positive-ion electrospray ionization mass spectrometer in multiple reaction monitoring (MRM) mode, using transitions of m/z 487.2 → 402.1 for olmutinib and m/z 488.2 → 401 for dasatinib (IS), respectively. The calibration curve (R 2 = 0.999) was linear over the range of 1–500 ng/mL. The recovery of olmutinib ranged from 85.8% to 95.5%. This method can be applied to pharmacokinetic studies of olmutinib.

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Eupatilin, mainly derived from Artemisia asiatica (Asteraceae), is an O-methylated flavone with various bioactivities. In the present study, a validated ultra-performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS) method was established for the quantification of eupatilin in rat plasma with the internal standard (IS) of tussilagone and the protein precipitation of plasma samples was performed using acetonitrile–methanol (9:1, v/v). The eupatilin and IS were eluted separately on a UPLC BEH C18 column (2.1 mm × 100 mm, 1.7 μm) with the gradient mobile phase consisted of 0.1% formic acid and acetonitrile. The protonated analytes were quantified by multiple reactions monitoring (MRM) mode with an electrospray ionization (ESI) source operated in positive ion mode. The calibration plots were found to be linear over the range from 2 to 1000 ng/mL for eupatilin in rat plasma. Both of the intra-day and inter-day precision variations (RSDs) were ≤13%. The recoveries of eupatilin in rat plasma were between 83.7% and 94.6%, and the accuracy of the method ranged from 95.8% to 107.6%. In addition, the validated method was applied to pharmacokinetic study of eupatilin after an intravenous dose of 2 mg/kg to rats.

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Summary

A new liquid chromatography tandem mass spectrometry (LC-MS/MS) assay for the quantification of seven isoflavones (daidzin, genistin, ononin, daidzein, glycitein, genistein, and formononetin) and coumestrol in vegetable extracts was developed. The separation was performed on a Zorbax SB-C18 column with a mixture of methanol (solvent A) and 0.1% (υ/υ) acetic acid in water (solvent B) under gradient conditions at 50°C with a flow rate of 1 mL min−1. The detection of analytes was performed by electrospray ionization, negative ionisation, in non-reactive MS2 mode for aglycons or in reactive MS2 mode for glycosides. The method shows a good linearity (r 2 > 0.9948) over the concentration range of 40–4000 ng mL−1 for all analytes, a good precision (CV < 11%) and accuracy (<10%). The method was successfully applied to quantify the isoflavones and coumestrol in vegetable extracts obtained from red clover (Trifolium pratense L., Fabaceae) and dyer's greenweed (Genista tinctoria L., Fabaceae) and can be used in the chemical characterization of vegetables with phytoestrogen content.

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Galantamine hydrobromide was subjected to oxidative stress degradation using hydrogen peroxide and analyzed as per the chromatographic conditions described in European Pharmacopoeia. The drug showed considerable degradation at ambient temperature resulting in the formation of two degradation products at relative retention times (RRTs) 0.63 and 2.52. The minor degradant at RRT 0.63 was identified as galantamine N-oxide. The principal degradant formed at RRT 2.52 was found to be unknown and has not been reported previously. The unknown impurity was identified by liquid chromatography-tandem mass spectrometry (LC-MS/MS) followed by isolation using semi-preparative high-performance liquid chromatography (HPLC). The isolated impurity was characterized using one-dimensional, two-dimensional nuclear magnetic resonance spectroscopy (1D and 2D NMR) and elemental analysis (EA). The principal degradant was found to be formed due to the generation of bromine and subsequent attack on the aromatic ring via in situ reaction between hydrogen bromide and hydrogen peroxide. The unknown impurity was characterized as (4aS,6R,8aS)-5,6,9,10,11,12-hexahydro-1-bromo-3-methoxy-11-methyl-4aH-[1]benzofuro [3a,3,2-ef] [2] benzazepin-6-ol.

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This paper is focused on the determination of three hexabromocyclododecane isomers, α, β, and γ, in the tissue of the most commonly consumed marine and farmed fish in Central Europe. The analytical procedure contains multiple steps: extraction, dialysis using semipermeable membranes, and a clean-up step using a silica gel column. Hexabromocyclododecane (HBCD) isomers were determined by sensitive isotope dilution liquid chromatography-tandem mass spectrometry (LC-MS/MS) method which is characterized by a low limit of detection (1 pg g−1 fresh weight). The recovery values obtained for individual isomers were in the range of 89–124%. The γ-HBCD isomer was detected in all samples. This isomer also had the largest percentage in comparison with the other isomers, except in salmon, in which the α-HBCD isomer was more abundant. The highest level of total HBCD was measured in mackerel (650 ± 195 pg g−1 fresh weight). Cluster analysis allowed the differentiation of groups of objects and the display of objects based on the degree of integration within the same group. Spearman’s rank correlation indicated no statistically significant difference between the levels of HBCD and the fat content in the fish samples.

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High-performance liquid chromatography coupled with fluorescence (HPLC-FD) and tandem mass spectrometric detection (LC-MS/MS) was studied as a versatile tool for fast and reliable determination of nine regulated quinolones in food of animal origin (Council Regulation 2377/90/ECC). The sample pre-treatment protocol includes double step extraction with acetonitrile followed by solid phase extraction (SPE) cleanup on hydrophobic-lipophilic balance (HLB) cartridge. The separation of quinolones in HPLC-FD determination was performed on C18 Zorbax column with a gradient mixture of aqueous formic acid, methanol, and acetonitrile. A multi-wavelength excitation/emission program was used for sensitive quinolones detection. The separation efficiency of newly available chromatographic columns: Gemini C18 and Synergi Polar RP (fully porous particles), as well as Kinetex PFP and Poroshell 120 EC-C18 (core-shell particles), was studied in liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) analysis. Appropriate gradient elution program was designed for each column. Multiple reaction monitoring was used for selective determination of each quinolone. LC-MS/MS allowed quinolones determination in less than 5 min. Both methods showed detection limits below maximum residue limits for quinolones residues in food commodities.

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