Chromatography-electrospray Tandem Mass Spectrometric Method Research Articles

An Ultra-High Performance Liquid Chromatography-Electrospray Tandem Mass Spectrometric Method for Screening and Simultaneous Determination of Anorexic, Anxiolytic, Antidepressant, Diuretic, Laxative and Stimulant Drugs in Dietary Supplements Marketed for Weight Loss.

The consumption of dietary supplements is increasing every year all over the world and has been accompanied by an increased frequency of adulteration of these products with synthetic pharmaceuticals. Analytical methods that allow testing for the presence of synthetic drugs in dietary supplements are needed to detect such fraudulent practices. To investigate the adulteration of dietary supplements marketed for weight loss using different commercial appeals, we developed an analytical method using ultra-high-performance liquid chromatography-electrospray tandem mass spectrometry (UHPLC-ESI-MS/MS) for simultaneous determination of 32 drugs, including anorexics, anxiolytics, antidepressants, diuretics, laxatives and stimulants. Separation was accomplished in 19 minutes using a Zorbax SB-C18 column and a gradient elution program with 0.05% formic acid in water/acetonitrile as a mobile phase. Limits of quantification ranged from 0.14 to 3.92 μg L-1, and accuracy ranged from 80.00 to 119.48%. A simple extraction procedure was used in the pretreatment step by dissolving the samples in 100% methanol followed by a 1000 to 10,000-fold dilution in the mobile phase and filtration through a Teflon membrane (0.2 μm). The method was applied to the screening and quantification of the drugs in 108 formulations marketed as food supplements for slimming, weight loss, thermogenics, and supplements for meal replacement. Caffeine and p-synephrine were found as stimulants in 80 samples, listed or not on the label.

A sensitive liquid chromatography–electrospray tandem mass spectrometric method for lancemaside A and its metabolites in plasma and a pharmacokinetic study in mice

A high-performance liquid chromatography tandem mass spectrometry (HPLC–MS/MS) method employing electrospray ionization (ESI) has been developed for simultaneous determination of lancemaside A (3- O-β- d-glucuronopyranosyl-3β, 16α-dihydroxyolean-12-en-28-oic acid 28- O-β- d-xylopyranosyl(1→3)-β- d-xylopyranosyl-(1→4)-α- l-rhamnopyranosyl-(1→2)-α- l-arabinopyranosyl ester) and its metabolites in mouse plasma. When lancemaside A (60 mg/kg) was orally administered to mice, echinocystic acid was detected in the blood. T max and C max of the echinocystic acid were 6.5 ± 1.9 h and 56.7 ± 29.1 ppb. Orally administered lancemaside A was metabolized to lancemaside X (3β, 16α-dihydroxyolean-12-en-28-oic acid 28- O-β- d-xylopyranosyl(1→3)-β- d-xylopyranosyl-(1→4)-α- l-rhamnopyranosyl-(1→2)-α- l-arabinopyranosyl ester) by intestinal microflora in mice, which was metabolized to echinocystic acid by intestinal microflora and/or intestinal tissues. Human intestinal microflora also metabolized lancemaside A to echinocystic acid via lancemaside X. These results suggest that the metabolism by intestinal microflora may play an important role in pharmacological effects of orally administered lancemaside A.

Validation of a solid-phase extraction and liquid chromatography–electrospray tandem mass spectrometric method for the determination of nine basic pharmaceuticals in wastewater and surface water samples

This paper reports the development and validation of a quantitative LC–electrospray (ESI)-MS/MS method for the simultaneous analysis of nine basic pharmaceuticals (flubendazole, pipamperone, cinnarizine, ketoconazole, miconazole, rabeprazole, itraconazole, domperidone and propiconazole) in environmental waters. Sample preparation consisted of solid-phase extraction on a Speedisk phenyl and a NH 2 solid-phase extraction tube for sample clean-up. Chromatography was performed on a pentafluorophenyl column in a total run time of 24 min. Due to different matrix effects measured in different surface water samples, standard addition was the only method to perform accurate quantification. Limits of detection and quantification were in the range of <0.05–1 ng/l and 0.05–10 ng/l, respectively. The method showed good precision and accuracy. Recoveries were in the range of 60–100%. This method allows to identify and quantify these pharmaceuticals in wastewater and surface water and enables to perform comprehensive studies on the occurrence in and removal of these drugs from influent and effluent wastewaters and surface waters.

Liquid chromatography–electrospray tandem mass spectrometric method for quantification of monensin in plasma and edible tissues of chicken used in pharmacokinetic studies: Applying a total error approach

A liquid chromatography–tandem mass spectrometric (LC–MS/MS) method was developed and validated for use in pharmacokinetic studies in order to determine the concentrations of monensin in plasma and edible tissues of chicken. Two sample preparations were performed, one for determining monensin concentrations in plasma using acetonitrile for protein precipitation and another one for determining monensin concentrations in muscle, liver, and fat using methanol–water followed by a clean up on a solid-phase extraction cartridge. Sample extracts were injected into the LC–MS/MS system, and a gradient elution was performed on a C 18 column. Narasin was used as internal standard. The LC–MS/MS method was validated using an approach based on accuracy profiles, and applicability of the method was demonstrated for the determination of monensin in chicken plasma, muscle, liver, and fat in a pharmacokinetic study.

Determination of gestrinone in human serum by liquid chromatography–electrospray tandem mass spectrometry

A rapid, sensitive and specific high-performance liquid chromatography–electrospray tandem mass spectrometric method has been developed for the determination of gestrinone (R 2323) in human serum using mifepristone (RU 486) as an internal standard. R 2323 was extracted from human serum by an ether extraction procedure. Multiple reaction monitoring was used to detect R 2323 and RU 486. The calibration curve was linear over the range of 3.5–177 ng/ml ( r 2≥0.99) with the limitation of detection of 0.8 ng/ml. The intra-day precision and accuracy, expressed as C.V. and RE, ranged from 2.3–13.7 to −4.8–3.0%. The inter-day precision and accuracy ranged from 5.5–14.8 to −6.7–3.1%. The mean recovery was 91.0% for R 2323, and 90.6% for the internal standard. The method was successfully applied to the pharmacokinetic study of R 2323.