气相色谱-质谱法测定富硒酵母中的硒蛋氨酸

建立了气相色谱-质谱（GC-MS）测定富硒酵母中硒蛋氨酸含量的方法。比较了3种从样品中提取硒蛋氨酸方法的效果。样品在三羟甲基氨基甲烷（Tris）缓冲液中酶解24 h后,以丁醇及三氟乙酸酐为衍生化试剂对硒蛋氨酸进行衍生化，采用选择离子模式对衍生物进行GC-MS测定。硒蛋氨酸的回收率为98.5%~103.7%,相对标准偏差为0.9%~2.4%,检出限为0.5 mg/L（S/N=3）。对实际样品进行测定，得到样品中硒蛋氨酸的含量结果。该法简便快速，准确可靠，灵敏度高。

Determination of Selenomethionine in Selenium-Enriched Yeast by Gas Chromatography-Mass Spectrometry

A method has been developed for the determination of selenomethionine in selenium-enriched yeast by gas chromatography-mass spectrometry (GC-MS). Three extraction methods were compared for extraction efficiency of selenomethionine from the samples. Selenomethionine in the samples was extracted for 24 h with proteinase in Tris buffer. The selenomethionine was derivatized with butanol and trifluoroacetic acid (TFA). The derivatization was accomplished in two steps, starting with the esterification of the carboxyl group of the selenoamino acid using butanol, followed by the acylation of the amino group with trifluoroacetic acid anhydride. The selected ion for monitoring selenomethionine was at m/z 349. The instrument operating conditions were optimized. The samples were analyzed by GC-MS with external standard method. Standard GC-MS chromatograms and mass spectra for selenomethionine were also obtained. The method was proved to be accurate and reliable. The recoveries of 98.5%-103.7% with relative standard deviations (RSDs) of 0.9%-2.4% (n = 6) and the correlation coefficient of 0.9978 were obtained. The detection limit of selenomethionine for the method was 0.5 mg/L (S/N = 3) and the selenomethionine contents of real sample was given.