[Simultaneous determination of six zeranols in milk samples by immunoaffinity solid phase extraction coupled with...

A method was developed for the simultaneous determination of α-zearalanol, β-zearalanol, α-zearalenol, β-zearalenol, zearalenone and zearalanone residues in milk samples by ultra-performance convergence chromatography-tandem mass spectrometry (UPC²-MS/MS) after immunoaffinity column-solid phase extraction (IAC-SPE). The sample was diluted with deionized water and cleaned with IAC-SPE. The chromatographic separation was performed on an ACQUITY UPC² Torus 2-PIC column (50 mm×3.0 mm, 1.7 μm) using the mobile phases of supercritical carbon dioxide and methanol containing 0.1% (v/v) formic acid with gradient elution. The separated compounds were detected in negative electrospray ionization (ESI^-) mode. The results showed no significant matrix effect after cleaning by IAC-SPE. The calibration curves of the six compounds were linear in the range of 1-200 ng/mL (correlation coefficients (r²) ≥ 0.9957). The recoveries were 75.9%-106.5% in the three spiked levels, and the intra-day and inter-day precisions were no more than 11.4%. The method is specific, environment friendly, and is suitable for the rapid determination of α-zearalanol, β-zearalanol, α-zearalenol, β-zearalenol, zearalenone and zearalanone residues in milk samples.