A sensitive and selective immunoaffinity column clean up coupled to UPLC-MS/MS for determination of trace methyl-3-quinoxaline-2-carboxylic acid in animal tissues

This paper described a reliable and simple method for the selective determination of MQCA in animal tissues using ultra high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS). A highly targeted immunoaffinity column was used for sample purification after enzymatic hydrolysis. The purified extracts were analyzed by reversed-phase HPLC-MS/MS in positive ESI and multiple reaction monitoring mode. The calibration curves showed good linearity with correlation coefficient (r(2)) larger than 0.995. The average recoveries at the spiked levels of 0.5, 2.0 and 20 mu g kg(-1) were 90.2% to 103.5% with intra-day and inter-day relatives standard deviations (RSD, n = 6) ranging from 1.8% to 6.7% and 3.5% to 7.6% respectively. The limit of quantification (LOQ) was 0.5 mu g kg(-1), which can fulfil the maximum residue level (MRL) of 4.0 mu g kg(-1) stipulated by the Agricultural Minister of China and the requirement of the confirmatory criteria according to the European Commission Decision 2002/657/EC. The method is sensitive, accurate, convenient and rapid, and has been successfully applied in real samples.