同位素稀释质谱法测定猪肉中克伦特罗含量的国际比对APMP. QM-S6

建立了同位素稀释质谱法（IDMS）测定猪肉中克伦特罗含量的高准确度方法，并应用于亚太计量规划组织（Asia Pacific Metrology Programme，APMP）开展的国际比对“猪肉中克伦特罗含量测定”（APMP. QM-S6）。本研究考察了影响测定结果的喷雾电压值、流动相、色谱柱、提取条件、净化条件等主要因素并进行了优化，并对测定结果的不确定度进行了评定。结果表明:流动相组成以及pH值会影响克伦特罗的质谱响应以及最优的电喷雾电压值；样品溶剂会影响克伦特罗的色谱保留，甲醇溶剂会引起严重的溶剂效应，甚至导致峰分裂；克伦特罗易在固相萃取柱及亲水性滤膜上吸附，且吸附材料和滤膜上吸附的杂质有可能被洗脱，引起基质效应，干扰测定。提取效率最高的方法是采用0.1%（v/v）甲酸乙腈溶液为提取溶剂，通过匀浆进行提取。方法检出限（以信噪比大于3计）为0.2 μg/kg。比对样品中克伦特罗的含量为5.18 μg/kg±0.50 μg/kg（k=2），比对结果与参考值等效一致，取得国际互认。该方法准确可靠，可为猪肉中克伦特罗的日常检测提供参考。

International comparison APMP. QM-S6:determination of clenbuterol in porcine meat by isotopic dilution mass spectrometry

A method was developed for the determination of clenbuterol in porcine meat by isotopic dilution mass spectrometry (IDMS). National Institute of Metrology of China (NIM) participated in the international comparison activity organized by Asia Pacific Metrology (APMP) and got an international mutual recognition result using this method. The important factors of the method, such as the spray voltage, mobile phase, chromatographic column, extraction, purification and filtration conditions were investigated to acquire optimum conditions. The optimization results showed that the composition and pH value of the mobile phase had effects on the response of the mass spectrum of clenbuterol and the optimal value of the spray voltage. The solvent of sample had influences on the chromatographic retention behavior of clenbuterol. It was found that methanol caused a serious solvent effect, even made chromatographic peak split. Since clenbuterol was easily adsorbed on hydrophilic filter membranes and solid phase extraction columns, there were interference suppressions for the quantification of clenbuterol because of the eluate of the solid phase extraction columns. The homogenate method with extraction solvent of 0.1% (v/v) formic acid in acetonitrile had the highest extraction efficiency. The limit of the detection (LOD, S/N>3) of the method was 0.2 μg/kg. The determination results of clenbuterol in the porcine meat by this method were 5.18 μg/kg±0.50 μg/kg (k=2). This method is accurate, reliable, reproducible, and suitable for the determination of clenbuterol with trace quantity in porcine meat.