Development and validation of novel LC–MS/MS method for determination of Lusutrombopag in rat plasma and its application to pharmacokinetic studies

Monitoring of Aflatoxins B1, G1, B2, and G2 in Spices from Riyadh Markets by Liquid Chromatography Coupled to Tandem Mass Spectrometry

A total of 1053 samples of spices were collected from Riyadh markets during 2022. The contamination with aflatoxins (AF) B1 (AFB1), B2 (AFB2), G1 (AFG1), and G2 (AFG2) was determined via liquid chromatography coupled to tandem mass spectrometry. AF extraction from spices was performed using an acetonitrile-formic acid mixture. The results obtained show that the highest value for AFB1 (3.865 μg/kg) was detected in the bay leaf sample, while the highest value for AFB2 (3.461 μg/kg) was found in red chili powder. The values of AFG1 and AFG2 did not exceed 2.59 μg/kg. The AF analysis shows that 24 out of 1053 samples (2.3%) contained one or more of these AFs. The highest percentage of contaminated samples was detected in black pepper. AFB1 was found in 21 samples of six types of spices, while AFG2 was detected in eight samples of four types of spices. Also, none of the samples exceeded the Saudi Food and Drug Authority and EU limits of 10 μg/kg. The present research is not a comprehensive study; however, it provides valuable information on AFB1, AFB2, AFG1, and AFG2 levels in the Kingdom of Saudi Arabia spices.

Simultaneous measurement of free and conjugated estrogens in surface water using capillary liquid chromatography tandem mass spectrometry

Given detrimental impacts induced by estrogens at trace level, determination of them is significant but challenging due to their low content in environmental samples and inherent weak ionisation. A modified derivatisation-based methodology was applied for the first time to detect estrogen in free and conjugated forms including some isomers simultaneously using liquid chromatography tandem mass spectrometry (LC-MSn). Derivatisation reaction with previously used 1,2-dimethyl-1H-imidazole-5-sulphonyl chloride allowed significant increase of mass spectrometric signal of analytes and also provided distinctive fragmentation for their confirmation even in complicated matrix. Then satisfactory recovery (>75%) for the majority of analytes was achieved following optimisation of solid phase extraction (SPE) factors. The linearity was validated over a wide concentration with the correlation coefficient around 0.995. The repeatability of this methodology was also confirmed via the intra-day and inter-day precision and was less than 11.73%. Validation of method quantification limits (MQLs) for all chosen estrogens was conducted using 1000 mL surface water, ranging from 7.0 to 132.3 pg L-1. The established methodology was applied to profile presence of targeted estrogens in natural surface water samples. Out of the ten compounds of interest, three free estrogens (E1, E2, E3) and two sulphate estrogens (E1-3S and E2-3S) were found over their MQLs, being in the range of 0.05-0.32 ng L-1.