气相色谱-串联质谱法测定婴幼儿配方奶粉中氯丙醇酯和缩水甘油酯

Determination of chloropropanol fatty acid esters and glycidol fatty acid esters in infant formula milk powder by gas chromatographytandem mass spectrometry

目的建立气相色谱-串联质谱法(gas chromatography-tandem mass spectrometry, GC-MS/MS)测定婴幼儿配方奶粉中3-氯-1,2-丙二醇脂肪酸酯(3-monochloropropane-1,2-diol ester, 3-MCPDE)、2-氯-l,3-丙二醇脂肪酸酯(2-monochloropropane-1,3-diol ester, 2-MCPDE)和缩水甘油脂肪酸酯(glycidol fatty acid esters, GEs)的分析方法。方法从奶粉样品中提取的脂肪先经溴代将缩水甘油酯转变成溴丙醇酯。在酸性条件下进行酯交换反应,水解生成游离态的溴丙醇和氯丙醇;水解液经碱中和后,经硅藻土固相萃取小柱净化,再经七氟丁酰基咪唑衍生;衍生液用异辛烷定容后供GC-MS/MS分析,采用同位素内标法定量。结果该方法在20~600 ng/mL范围内线性良好(r2≥0.99),检出限为0.005 mg/kg,定量限为0.015 mg/kg (检出限和定量限均以相应的氯丙醇或缩水甘油计)。0.1、0.5和1.0 mg/kg水平下的加标回收率在89.7%~105.6%之间,相对标准偏差均不大于5.56%。结论该方法灵敏、准确可靠,适合婴幼儿配方奶粉中3-MCPDE、2-MCPDE和GEs的同时测定。

Objective To establish a method for the determination of 3-monochloropropane-1,2-diol ester(3-MCPDE), 2-monochloropropane-1,3-diol ester(2-MCPDE) and glycidol fatty acid esters(GEs) in infant formula by gas chromatography-tandem mass spectrometry(GC-MS/MS). Methods After bromination of the fat extracted from milk powder, the glycidyl ester was converted into bromopropanol ester. The ester exchange reaction of bromopropanol ester and chloropropanol ester in the sample occurred under acid condition, and the esters were hydrolyzed to free bromopropanol and chloropropanol. The hydrolysate was neutralized by alkali, purified by diatomite solid phase extraction column, and then derivatized by heptafluorobutyryl imidazole. The derivatization solution was diluted with isooctane and analyzed by GC-MS/MS, and quantified by isotope internal standard method. Results The method showed a good linear relationship in the concentration range of 20–600 ng/mL(r2≥0.99). The limits of detection(LODs) and limits of quantification(LOQs) were 0.005 and 0.015 mg/kg, respectively(calculated as chlorpropanol). The recoveries spiked at 0.1, 0.5 and 1.0 mg/kg were between 89.7%–105.6%, with relative standard deviations(RSDs) less than 5.56%. Conclusion This method is sensitive, accuracy and reliability, and suitable for the determination of 3-MCPDE, 2-MCPDE and GEs in infant formula.