液相色谱-串联质谱法测定茶叶中4种黄曲霉毒素

Determination of 4Kinds of Aflatoxin in Tea by Liquid Chromatography-Tandem Mass Spectrometry

5.000 0g样品经20mL乙腈超声提取20min后离心,取4mL提取液直接通过Prime HLB固相萃取柱,收集净化液,再用2mL乙腈分两次洗脱,合并净化液,氮吹浓缩至约4mL,用pH 7.4磷酸盐缓冲液定容至50mL,全部通过免疫亲和柱,用20mL水淋洗,最后用4mL乙腈分2次洗脱,收集洗脱液,氮吹浓缩至近干,用甲醇-水(50+50)溶解并定容至1mL,过0.45μm有机相滤膜。滤液经VP-ODS C18色谱柱(150mm×2.0mm,4.6μm)分离,以乙腈和0.1%(体积分数)甲酸溶液(含0.01mol·L-1乙酸铵)为流动相进行梯度洗脱。质谱分析中采用电喷雾正离子源和多反应监测模式。黄曲霉毒素B1、B2、G1、G2质量浓度均在0.06~5.0μg·L^(-1)内与其对应的峰面积呈线性关系,检出限(3S/N)均为0.02μg·kg-1。加标回收率为81.5%~89.6%,测定值的相对标准偏差(n=6)为3.6%~6.5%。

The sample（5.000 0 g）was ultrasonically extracted with 20 mL of acetonitrile for 20 min.After centrifugation,4 mL of the extract was directly purified through the Prime HLB solid phase extraction column,the purified solution was collected.Then the column was eluted with 2 mL acetonitrile in 2 portions,and the purified solution was combined,concentrated to about 4 mL by nitrogen blowing,diluted to 50 mL with phosphate buffer solution（pH 7.4）.The solution was passed through the immunoaffinity column and the column was rinsed with20 mL of water and finally eluted with 4 mL of acetonitrile in 2 portions.The eluent was collected and concentrated to nearly dry by nitrogen blowing.The residue was dissolved and diluted to 1 mL with methanol-water（50＋50）,and the solution was filtrated with 0.45μm organic phase filter.The filtrate was separated on a VP-ODS C18 column（150 mm×2.0 mm,4.6μm）,with acetonitrile and 0.1%（φ）aqueous formic acid（containing 0.01 mol·L-1 ammonium acetate）as the mobile phase for gradient elution.Electrospray positive ion sources and multiple reaction monitoring mode were used for mass spectrometry analysis.Linear relationships were found between peak areas and mass concentrations of aflatoxin B1,B2,G1,G2 in the same range of 0.06-5.0μg·L^（-1）,with the same detection limit（3 S/N）of 0.02μg·kg-1.Values of recovery obtained by standard addition method were 81.5%-89.6%,and the relative standard deviations（n=6）of the measured values were 3.6%-6.5%.