Nitarsone is an organoarsenic antiprotozoal drug widely used to treat blackhead disease in turkeys and chickens. However, since its biological conversion into inorganic arsenic, a carcinogen was known, its residue in foods should be regu-lated. Thus, here, a novel method to determine residual nitarsone in various food commodities (pork, milk, egg, halibut, eel, and shrimp) using QuEChERS and LC-MRM was developed. The developed method was successfully validated through specificity, linearity (coefficient of determination, at least 0.991), recovery (R, 63.6 - 85.6%), precision (the relative standard deviation of R, 0.5 - 10.6%), and sensitivity (the lower limit of quantitation, 5 ppb) by following the Ministry of food and drug safety (MFDS) guidelines. The present method is the first mean to quantitate nitarsone using LC-MRM, and it was designed to be conveniently merged into a new method to quantitate multiple veterinary drugs for the positive list system (PLS). Therefore, the present method could contribute to fortify the food safety system in South Korea.
An analytical method was developed for hypoxia-inducible factor (HIF) stabilizers based on QuEChERS (Quick, Easy, Cheap, Effective, Rugged, and Safe) sample preparation and liquid chromatography–high resolution mass spectrometry analysis. HIF stabilizers potentially enhance the performance of athletes, and hence, they have been prohibited. However, the analysis of urinary HIF stabilizers is not easy owing to their unique structure and characteristics. Hence, we developed the QuEChERS preparation technique for a complementary method and optimized the pH, volume of extraction solvent, and number of extractions. We found that double extraction with 1% of formic acid in acetonitrile provided the highest recovery of HIF stabilizers. Moreover, the composi-tion of the mobile phase was also optimized for better separation of molidustat and IOX4. The developed method was validated in terms of its precision, detection limit, matrix effect, and recovery for ISO accreditation. To the best of our knowledge, this is the first demonstration of the application of the QuEChERS method, which is suitable as a complementary analytical method, in antidoping.
As a part of efforts to establish the positive list system (PLS) in South Korea, a method to determine residual ema- mectin benzoate (EB) in various aquatic products using QuEChERS-EDTA and LC-MRM was developed. The developed method was validated in the aspects of specificity, linearity (correlation coefficient of at least 0.996), sensitivity (the limit of detection and the lower limit of quantitation ≤ 5 ng/g), recovery (the recovery range of 87.4 and 96.2), and precision (the relative standard deviation of recovery between 0.9 and 13.5). Additionally, the validated method was successfully applied for monitor- ing EB contamination in eel, halibut, and shrimp collected from local food markets. To our knowledge, the present method is the first one to determine residual EB in various aquatic products at the level satisfying the PLS and could contribute to the estab- lishment of the PLS in South Korea.