A liquid chromatography - tandem mass spectrometric method was developed for the determination of o-tyrosine in y-ray irradiated protein-rich food. The sample was homogenized and hydro-lyzed with parenzyme at 37 ℃ for 24 h. The digestion solution was purified with n-hexane eliminating fat, deproteinated with zinc acetic acid solution, and then determined by HPLC - MS/MS. The quantitation limit was 0. 1 mg/kg. The recoveries of o-tyrosine at three spiked levels of 0. 1, 0. 5 and 1. 0 mg/kg were in the range of 80% -97% , with RSDs( n = 6 ) of 6. 3% -12. 9% . The o-tyrosine contents in chicken, pork, beef, fish and shrimp irradiated with 2, 5, 10 kGy of y-ray ranged from 0.095 mg/kg to 0. 677 mg/kg, which were obviously higher than those in the unirradiated meat samples , and presented linear relationships with the irradiance dose. The method showed good reproduc-ibility and sensitivity.%应用液相色谱-串联质谱(HPLC- MS/MS )技术建立了含蛋白质辐照食品中邻酪氨酸的检测方法.样品经胰蛋白酶于37℃水解过夜,正己烷去脂,乙酸锌沉淀蛋白净化后,HPLC-MS/MS检测.方法的定量下限为0.1 mg/kg,邻酪氨酸在0.1,0.5,1.0 mg/kg加标水平的回收率为80%-97%,相对标准偏差(RSD,n=6)为6.3%-12.9%.在2.0,5.0,10 kGy3个辐照剂量水平下,鸡肉、猪肉、牛肉、鱼肉和虾肉中的邻酪氨酸含量为0.095-0.677 mg/kg,邻酪氨酸含量与辐照剂量呈线性相关,相关系数(r)大于0.98.该方法灵敏、实用性强.
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