牛肉、牛奶中可的松和氢化可的松含量分析

采用液相色谱-串联质谱技术分析我国部分地区市售牛肉、牛奶中可的松和氢化可的松的含量水平。均质的牛肉或牛奶样品在乙酸-乙酸钠缓冲液中酶解后用甲醇提取，提取液用石墨化碳黑固相萃取小柱和氨基固相萃取小柱净化，洗脱液氮吹至干并用甲醇溶液定容，液相色谱-串联质谱测定。采用SPSS?21.0软件进行数据分析。对采自我国9?省市的346?份牛肉和牛奶样品进行检测，分析牛肉和牛奶中可的松和氢化可的松的存在水平。牛肉和牛奶中均检出可的松和氢化可的松，检出率在86.1%～100.0%之间，检出含量范围为0.02～74.88?μg/kg。牛肉中可的松和氢化可的松的含量平均值（中位数）分别为1.69（1.14）?μg/kg和12.16（8.14）?μg/kg，牛奶中可的松和氢化可的松的含量平均值（中位数）分别为0.23（0.23）?μg/kg和0.72（0.72）?μg/kg。牛肉和牛奶中氢化可的松与可的松的含量均呈显著正相关。

Analysis of Cortisone and Cortisol in Beef and Milk

Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used to analyze the occurrence of cortisone and cortisol in beef and milk marketed in some regions of China. Homogenized samples were digested in acetic acid-sodium acetate buffer, and extracted with methanol. Then, the extract was purified on graphitized carbon black (GCB) and amino (NH2) solid phase extraction (SPE) catrideges. The eluate was pooled and blown to dryness by N2, and the residue was redissoved in methanol-water mixture before being analyzed by LC-MS/MS. Data analysis was carried out using SPSS version 21.0. A total of 346 beef and milk samples from nine provinces and municipalities in China were analyzed by LC-MS/MS. Cortisone and cortisol were detected in both beef and milk with detection rates ranging from 86.1% to 100.0% at concentration levels of 0.02–74.88 μg/kg. The mean (median) contents of cortisone and hydrocortisone in beef were 1.69 (1.14) and 12.16 (8.14) μg/kg, respectively, and the mean (median) contents of cortisone and hydrocortisone in milk were 0.23 (0.23) and 0.72 (0.72) μg/kg, respectively. The contents of hydrocortisone and cortisone in beef and milk were significantly positively correlated with each other.