Abstract: An ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method with solid phase extraction (SPE) was established for the detection of ethephon residue in milk. In the sample pretreatment stage, formic acid solution was selected as the extraction solvent, and the extract was purified on an amino SPE column. The target compound was separated on a Waters Anionic Polar Pesticide column (150 mm × 2.1 mm, 5 μm) using gradient elution with a mobile phase consisting of 0.1% formic acid containing 50 mmol/L ammonium formate and acetonitrile. The detection was performed using electrospray?ionization in the negative ion mode with multiple reaction monitoring, and the matrix-matched external standard method was used for quantification. The calibration curve for ethephon showed an excellent linearity (r2 > 0.99) in the concentration range of 2 to 100 ng/mL, and the limit of detection and limit of quantification of this method were 0.5 and 1.0 μg/kg, respectively. At spiked concentration levels of 1.0, 2.0 and 10.0 μg/kg, the recoveries were between 92.50% and 113.76%, and the precision, expressed as relative standard deviation, ranged from 3.04% to 4.60%. In conclusion, the UPLC-MS/MS method has the advantages of high accuracy, specificity, and repeatability, and is very suitable for the determination of ethphon in milk.

Key words: ultra-high performance liquid chromatography-tandem mass spectrometry; milk; ethephon; solid phase extraction

摘要： 基于固相萃取-超高效液相色谱-串联质谱法建立牛乳中乙烯利残留检测方法。样品预处理阶段，以甲酸溶液作为提取溶剂，采用氨基固相萃取柱净化样品，以0.1%甲酸-50 mmol/L甲酸铵溶液和乙腈为流动相，采用Waters Anionic Polar Pesticide色谱柱（150 mm×2.1 mm，5 μm），以梯度洗脱方式对目标物进行分离。以电喷雾电离负离子模式扫描，在多反应监测模式下，采用基质匹配外标法定量。结果表明，乙烯利在2～100 ng/mL质量浓度范围内展现出良好的线性关系（R2＞0.99），检出限为0.5 μg/kg，定量限为1.0 μg/kg。在1.0、2.0、10.0 μg/kg加标水平下，加标回收率为92.50%～113.76%，精密度为3.04%～4.60%。综上所述，该方法具有准确度高、特异性强、重复性好等优点，适用于牛乳中乙烯利残留测定。

关键词: 超高效液相色谱-串联质谱法；牛乳；乙烯利；固相萃取