关键词: 液相色谱-电喷雾串联质谱；甾类；β-受体激动剂；乳；乳粉

Abstract: A quick confirmative method for the determination of residual amounts of 11 anabolic hormones and 9 agonists in milk and milk powder by liquid chromatography-tandem mass spectrometry (LC-MS-MS) was developed. Samples were extracted with acetonitrile containing 0.1% formic acid by volume. After lipid removal by liquid-liquid extraction with n-hexane, the purification of the extract was carried out on an Oasis HLB cartridge by solid-phase extraction. The analytes were separated on a C8 column employing a mobile phase composed of a mixture of methanol with 0.1% formic acid and 0.1% formic for gradient elution. The tandem mass spectral acquisition was done in the positive electrospray ionization mode utilizing multiple reaction monitoring. External standard method was applied for quantization. The results indicated that the limits of quantification (LOQs, RSN = 10) for 20 target compounds ranged from 0.1 to 1.0 μg/kg, and the linear range was 0.05–50 μg/L with correlation coefficients larger than 0.996. The average recoveries at different spiked concentration levels ranged from 52.8% to 97.4% with RSD of 2.8%–9.6% (n = 6). The proposed method has been applied for the rapid determination of real samples of milk and milk powder with simple operation and accurate results.

Key words: liquid chromatography-tandem mass spectrometry (LC-MS-MS); anabolic hormones; β-agonists; milk; milk powder