Matrix Solid-Phase Dispersion Combined with GC–MS/MS for the Determination of Organochlorine Pesticides and Polychlorinated Biphenyls in Marketed Seafood

An analysis method based on matrix solid-phase dispersion (MSPD) and gas chromatography tandem mass spectrometry was developed and applied for the analysis for organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in the marketed seafood such as fish, shrimp and shellfish. The parameters of the method including the type and amount of the absorbent, as well as the type and volume of the elution solution were optimized. The recoveries were between 70 and 120% with RSDs less than 20%, and the LODs and LOQs were 0.011–0.046 and 0.037–0.153 ng g^?1 under optimized conditions. The results showed that most of the OCPs and PCBs were detectable in the marketed samples with the average concentration range of 0.722–14.206 and 0.034–1.184 ng g^?1, respectively. Among the 21 OCPs detected, DDTs had a relatively higher concentration level. And in the PCBs, the concentration of PCB28 was over 45% of the total PCBs determined in all the samples. The developed method was simple, fast and effective, and could successfully be applied for trace amount of OCPs and PCBs determination in seafood matrixes.     

Detection of Benzo[a]pyrene in Fried Food by Ultrasound-Assisted Matrix Solid-Phase Dispersion and Isotope Dilution GC–MS

A simple, sensitive and reliable analytical method was developed for the detection of benzo[a]pyrene in fried food using gas chromatography-mass spectrometry with an isotope-labelled internal standard. Samples were directly extracted and purified by the ultrasound-assisted matrix solid-phase dispersion (MSPD) procedure. The simple pretreatment procedures were tested with different absorbents (C18, NH₂, Oasis, and SiO₂). The optimal ultrasonication-assisted MSPD was achieved by MSPD-SiO₂ and sonication for 10 min in an ultrasonic bath. The samples were quantified using benzo[a]pyrene-d₁₂ as the internal standard. An analysis of the samples spiked with different levels of benzo[a]pyrene showed recoveries ranging from 84.6 to 103.2 %, with an RSD of 3.21–8.32 %, depending on the spiking level. This method was thus shown to be suitable for the detection of benzo[a]pyrene in fried food.

     

Matrix Solid-Phase Dispersion Micro-Extraction of Pesticides from Single Insects with Subsequent GC–MS Analysis

A simple multiresidue method based on matrix solid-phase dispersion (MSPD) micro-extraction was studied to determine various organophosphorus (OPPs) and pyrethroid pesticides in single insects. Optimisation of the relevant parameters showed that, in the case of OPPs and permethrin, extraction from 40 mg of isopod (Porcellio scaber) and the use of C₈-bonded silica and 100 L of ethyl acetate were the best conditions, while silica and 3.5 mL of n-hexane were optimal for the less polar pyrethroids. Subsequently, 1 L (ethyl acetate) or 20 L (n-hexane) of the extracts were analysed by GC–MS without any further clean-up. The limits of detection (LODs), in the SIM mode, were 5–80 ng g^–1 for most OPPs and trans-permethrin (cis-permethrin 0.3 ng g^–1) when using the C₈-bonded silica/ethyl acetate procedure, and 5–35 ng g^–1 for the pyrethroids when using the silica/n-hexane procedure. The recoveries of the OPPs and pyrethroids from the isopods were 52–94%. The practicality of the proposed method was studied for pesticides in isopods which had been fed polluted leaves.     

Analysis of Linarin and Its Metabolites in Rat Urine by LC–MS/MS

Liquid chromatography–ion trap mass spectrometry was employed to investigate the metabolism of linarin in rats. Identification and structural elucidation of the metabolites were performed by comparing the differences in molecular masses, retention times, and full scan MS ⁿ spectra between linarin and its metabolites. Six metabolites (acacetin, apigenin, acacetin glucuronide, apigenin glucuronide, acacetin sulfate, apigenin sulfate) were detected in rat urine after oral administration of linarin at the dose of 50 mg kg^?1. Furthermore, a selective and sensitive liquid chromatography–triple quadruple mass spectrometry assay was developed and validated for the simultaneous determination of linarin and acacetin (the major metabolite of linarin) in rat urine. Chromatographic separation was carried out on a C₁₈ column, and mass spectrometric detection was performed using a triple-quadrupole mass spectrometer coupled with an electrospray ionization source in the positive ion mode. Quantitation of linarin and acacetin was performed using selected reaction monitoring of precursor–product ion transitions at m/z 593 → 285 for linarin, 285 → 242 for acacetin, and 303 → 153 for hesperitin (internal standard), respectively. The assay exhibited good linearity (r > 0.9900) for both linarin and acacetin. The intra- and inter-day precisions were <13.4 % and the accuracy was between ?8.1 and 3.1 %. The method was successfully applied to the urinary excretion study of linarin in rats after oral administration of linarin.     

Determination of flurbiprofen in pharmaceutical preparations by GC–MS

This article describes a gas chromatography–mass spectrometry (GC–MS) method for the determination of flurbiprofen in pharmaceutical preparations. The method is based on the derivatization of flurbiprofen with N-methyl-N-(trimethylsilyl)trifluoroacetamide (MSTFA). For GC–MS, electron ionization mode (EI = 70 eV) and selected ion monitoring (SIM) mode were used for quantitative analysis (m/z 180 for flurbiprofen). Calibration curve was linear between the concentration range of 0.25–5.0 μg/mL. Intra- and inter-day precision values for flurbiprofen were less than 3.64, and accuracy (relative error) was better than 2.67%. The mean recovery of flurbiprofen was 99.4% for pharmaceutical preparations. The limits of detection and quantification of flurbiprofen were 0.05 and 0.15 μg/mL, respectively. No interference was found from tablet excipients at the selected assay conditions. Also, the method was applied for the quality control of five commercial flurbiprofen dosage forms to quantify the drug and to check the formulation content uniformity.     

Determination of steroid hormones in blood by GC–MS/MS

This paper presents the development, optimization and validation of a methodology to determine nine key steroid hormones (viz. pregnenolone, progesterone, dehydroepiandrosterone, androstenedione, testosterone, dihydrotestosterone, estrone, 17α-estradiol and 17β-estradiol) expressed in the steroidogenesis in biological fluids. The analytical method allows for the determination of steroid hormones in blood plasma and serum down to 0.08–0.16 ng/mL for estrogens, 0.20–0.36 ng/mL for androgens and 0.36–0.43 ng/mL for progestagens. These limits of detection were obtainable using a two-step solid-phase clean-up for fractionation and elimination of interfering lipids (fatty acids, phospholipids, glycerides and sterols) from the steroid hormones. The accuracy of the method was 50–112% in the range 0.10 to 2.00 ng/mL.     

Determination of Estragole in Fennel Herbal Teas by HS-SPME and GC–MS

Estragole, a volatile phenylpropanoid contained in a variety of edible herbs, has been demonstrated to be genotoxic and carcinogenic, and its addition as a flavoring substance to foodstuffs has been banned by the regulatory bodies of the European Union. Fast and accurate analytical methods for its determination in herbs are thus necessary to assess the dietary exposure of this substance in humans and, in particular, to sensitive groups. In the present study, headspace solid-phase microextraction (HS-SPME) combined with gas chromatography–mass spectrometry (GC–MS) was applied for determination of estragole in infusions from different widely used commercial herbal teas based on Foeniculum vulgare (fennel) seeds. The optimized HS-SPME extraction conditions involved the use of a polydimethylsiloxane fiber exposed to the herbal infusion for 20 min at 50°C followed by GC–MS analysis. The method was fully validated for linearity, sensitivity, accuracy, and precision and applied to real samples; the level of estragole in infusions of commercial fennel seed teas was found to be within 50–250 µ`^?1.     

Quantitative Determination of Lobeline Hydrochloride in Rabbit Plasma by LC–MS–MS and Its Application

A sensitive and selective liquid chromatography tandem mass spectrometry method for quantitative determination of lobeline hydrochloride in rabbit plasma was developed and validated. After addition of triazolam as internal standard, protein precipitation by acetonitrile was used as sample preparation. Chromatographic separation was achieved on a Zorbax SB-C18 column with acetonitrile-0.1% formic acid as mobile phase with gradient elution. Electrospray ionization source was applied and operated in positive ion mode; multiple reaction monitoring mode was used for quantification using target fragment ions m/z 338.1 → 315.8 for lobeline hydrochloride and m/z 342.9 → 308.0 for the IS. Calibration plots were linear over the range of 2–500 ng mL^?1 for lobeline hydrochloride in plasma. Lower limit of quantitation for lobeline hydrochloride was 2 ng mL^?1. Mean recovery of lobeline hydrochloride from plasma was in the range 97.5–102.3%. RSD of intra-day and inter-day precision were both <9%. This developed method is successfully used in pharmacokinetic study of lobeline hydrochloride in rabbit.     

Simultaneous Determination of Methadone,Heroin, Cocaine and their Metabolites in Urine by GC‐MS

Abstract

A gas chromatographic‐mass spectrometric (GC‐MS) method for the determination of methadone, heroin, cocaine, and their metabolites in urine using Selected Ion Monitoring (SIM) was developed. Following a liquid‐liquid extraction with Toxitubes A^® and using their deuterated analogs as internal standards, the analytes were derivatized with 99:1 (v/v) N,O‐bis‐trimethylsilyl‐trifluoroacetamide/trimethylchlorosilane and injected by hand, in the splitless mode, at 240°C and a purging time of 0.75 min. The mass selective detector was kept at 300°C and molecules were ionized in the electron impact mode, using an energy of 70 eV. The detector response was linear for all drugs studied over the range 50–1000 ng/mL.     

GC–MS Determination of Sucralose in Splenda

Sucralose (1,6-dichloro-1,6-dideoxy-β-d-fructofuranosyl-4-chloro-4-deoxy-α-d-galactopyranoside) is a high-intensity non-nutritive sweetener derived from sucrose. Determination of sucralose in food is important to ensure consistent product quality. The authors have developed a new method for determination of sucralose. The sucralose was converted into its trimethylsilyl (TMS) ether and qualitative and quantitative analysis were achieved by GC–MS and GC–FID, respectively, using myo-inositol ester as the internal standard. A good linear relationship between response and amount of sucralose TMS ether was obtained in the range 0.005–0.06 mg mL^?1 (r = 0.9994). The detection limit was 0.25 ng.     

Residue Analysis and Determination of IMI Herbicides in Sunflower and Soil by GC–MS

Sunflower agriculture is an important subsector that plays a key role in the economy of Turkey, contributing 1.38 million tonnes. The aim of this study is to investigate the levels of imidazolinone (IMI) group herbicides in Thrace Region, Turkey. In particular, we aimed to determine the residue levels of imazamox, a herbicide used in sunflower production in Thrace Region, in soil, different parts of plant, and seed. Five herbicides were identified in sunflower samples using solid–liquid extraction with gas chromatography–electrospray ionization mass spectrometry (GC–EI–MS) on single-quadruple instruments in selected ion monitoring (SIM) mode. The optimized conditions were found to be mobile-phase flow rate of 1 mL min^?1 and injection volume of 3 μL in programmed temperature vaporization (PTV) solvent vent mode. The recovery of imazamox, imazaquin, imazethapyr, imazapyr, and imazapic from sunflower plant and soil was 89 and 99, 104 and 105, 92 and 93, 96 and 92, and 99 and 96%, respectively.     

Determination of Antioxidants and Preservatives in Cosmetics by SPME Combined with GC–MS

A rapid and simple procedure for the determination of antioxidants and preservatives in cosmetics has been developed utilizing solid-phase microextraction combined with GC–MS. A silica fiber coated with polyacrylate provided the highest extraction efficiency. Detection limits in the range from 0.4 to 8.5 ng mL⁻¹ were obtained. Linearity is over a wide range from 1 to 2,000 ng mL⁻¹ with a relative standard deviation under 16%. Cosmetic from a local supermarket were analysed for antioxidants and preservatives to demonstrate the effectiveness of the proposed method. The concentration of antioxidants and preservatives determined was 20–1,218 μg g⁻¹ for methylparaben and 5–3,779 μg g⁻¹ for propylparaben.     

Simultaneous Determination of Ramipril and Its Active Metabolite Ramiprilat in Human Plasma by LC–MS–MS

A selective, rapid and sensitive liquid chromatography tandem mass spectrometry method has been developed for the simultaneous determination of ramipril and ramiprilat in human plasma using enalapril as the internal standard via one-step extraction with ethyl acetate under acidic condition. The analysis was carried out on a Diamonsil C₁₈ column (150 mm × 4.6 mm i.d., 5 μm) with a mobile phase consisting of 1% formic acid-acetonitrile (25:75, v/v) at a constant flow rate of 0.5 mL min^?1. The detection was performed on a triple-quadruple tandem mass spectrometer by selective reaction monitoring mode via electrospray ionization. Linear calibration curves of ramipril and ramiprilat were obtained in the concentration range of 0.107–107.0 and 0.262–105.0 ng mL^?1, respectively. The intra- and inter-day precision (RSD) values were below 8.2 and 4.8% for ramipril, 10.4 and 12.3% for ramiprilat, and accuracy (RE) were within ±5.5 and ±3.2%, respectively at all QC levels. The method was utilized to support clinical pharmacokinetic studies in healthy volunteers following oral administration of ramipril tablets.     

Determination of Asiaticoside in Rat Plasma by LC–MS–MS and Its Application to Pharmacokinetics Studies

A rapid and sensitive LC–MS–MS method was developed and validated for the determination of asiaticoside in rat plasma. Asiaticoside was extracted by protein precipitation with acetonitrile, and separated on a C₁₈ column. The total analytical time was relatively short (4 min), and the limit of quantification was 38 ng mL^?1 using 100 μL of rat plasma. Asiaticoside and the internal standard (felodipine) were monitored in the multi-reaction-monitoring mode as follows: m/z 957.4 → 469.3 and m/z 382.2 → 145.1, respectively. Calibration was linear over a concentration range from 38 to 7,600 ng mL^?1, and the correlation coefficient was greater than 0.998. The recoveries of asiaticoside from plasma were better than 85%, and RSDs of inter-day and intra-day assays were below 10.1%. The method is sensitive and specific, and suitable for pharmacokinetic studies of asiaticoside in rats.     

Determination of Nicotine in Dried Mushrooms by Using a Modified QuEChERS Approach and GC–MS–MS

Levels of nicotine higher than the maximum residue level were detected in edible mushrooms. Analyses of self-collected and purchased dried mushrooms were performed with a QuEChERS approach. A small amount (2.5 g) of dried sample matrix was mixed with 5 mL sodium hydroxide solution, 2.5 g of sodium sulfate/sodium chloride mixture (4:1) and 5 mL ethyl acetate. The organic phase was cleaned by using dispersive solid-phase extraction and analysed by GC–MS–MS. The linear range of the method was 0.01–10.00 mg kg^?1 and the limit of detection 0.006 mg kg^?1 on dry weight basis by using EURACHEM method.