液相色谱-电感耦合等离子质谱联用法测定大豆中的5种硒形态

Determination of 5 kinds of selenium species in soybean by liquid chromatography-inductively coupled plasma mass spectrometry

目的建立液相色谱-电感耦合等离子质谱法(liquid chromatography-inductively coupled plasma mass spectrometry,LC-ICP-MS)测定谷物类大豆样品中5种硒形态[硒代胱氨酸(SeCys2)、甲基硒代L-半胱氨酸(MeSeCys)、亚硒酸根(SeⅣ)、硒代蛋氨酸(SeMet)和硒酸根(SeVI)]的分析方法。方法样品采用超声水解,加入链酶蛋白酶E提取,经C18反向色谱柱(4.6 mm×150 mm,5μm,100Å)分离,以30 mmol/L磷酸氢二铵、0.5 mmol/L四丁基溴化铵、2%甲醇为流动相,流动相的pH用甲酸调节至5.8~6.0,通过ICP-MS测定5种硒形态。结果经方法优化后,LC-ICP-MS方法可以在8 min内将5种硒形态完全分离,且各个硒形态标准曲线的线性关系良好(r 2≥0.995),方法检出限为0.5~1.0μg/L,定量限为1.5~3.0μg/L,加标回收率为97.34%~100.33%,相对标准偏差为0.46%~1.2%。结论本方法具有前处理简单、快捷,灵敏度高,分析速度快等优点,适用于大豆食品中硒的形态分析。

Objective To establish a method for determination of 5 different forms of selenium[selenium cystine(SeCys2),methyl selenium generation L-cysteine(MeSeCys),and selenium acid radical(SeⅣ),selenomethionine(SeMet)and selenium acid group(SeVI)]in grain soybean samples by liquid chromatography with inductively coupled plasma mass spectrometry(LC-ICP-MS).Methods The samples were hydrolyzed by ultrasound and extracted by adding pronase E,and separated by C18 chromatographic column(4.6 mm×150 mm,5μm,100Å)using 30 mmol/L diammonium phosphate,0.5 mmol/L tetrbutyl ammonium bromide,and 2%methanol as mobile phase.The pH of the mobile phase was adjusted to 5.8~6.0 by formic acid,then 5 selenium forms were determined by ICP-MS.Results After the optimization of the method,5 selenium forms could be separated completely in 8 minutes by LC-ICP-MS,and the linear relationship of the standard curves of selenium forms was good(r^2≥0.995).The limits of detection the method were 0.5–1.0μg/L,the limits of quantitation were 1.5–3.0μg/L,the recovery rates were 97.34%–100.33%,and the relative standard deviations were 0.46%–1.2%.Conclusion This method has the advantages of simple,fast pretreatment,high sensitivity and fast analytical speed,and is suitable for speciation analysis of selenium species in soybean food.