RESUMO
A method was developed for the simultaneous quantitative and confirmatory determination of 3-methylquinoxaline-2-carboxylic acid (MQCA) residues in pork by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The sample was hydrolyzed with 0.3 mol/L hydrochloric acid solution, and MQCA was extracted by water bath oscillation. MQCA was first extracted with acetonitrile and ethyl acetate and then re-extracted from the extraction solution with 0.1 mol/L sodium hydroxide solution. Then MQCA was purified by an anion exchange solid phase extraction column. The chromatographic separation was performed using an Agilent Eclipse Plus C18 column (50 mm×3.0 mm, 1.8 µm). The quantitative analysis was performed by the matrix matching addition method. The correlation coefficient of MQCA in the range of 1.0-50 µg/L was greater than 0.99. The recovery was 90.5%-119.6% at the spiked levels of 0.5, 1.0 and 5.0 µg/kg, and the relative standard deviation was 3.14%-4.22%. The method can be used for the rapid quantitative determination of 3-methylquinoxaline-2-carboxylic acid residues in pork.
