双酶解-液液萃取-气相色谱质谱法测定糕点中丙酸及其盐类

Determination of propionic acid and its salts in cakes by liquid-liquid extraction-GC-MS combined with dual enzymatic hydrolysis

该文建立了一种测定糕点中丙酸及其盐类的双酶解-液液萃取-气相色谱质谱分析方法。样品在37℃磷酸缓冲液中经酶解后除去蛋白质与淀粉,加入NaOH调节pH>10,丙酸在离子状态下用乙醚萃取去除非极性杂质。水相用磷酸调节pH<4,丙酸在分子状态下经乙酸乙酯萃取去除极性杂质并定容,采用DB-WAX毛细管气相色谱柱(30 m×0.25 mm,0.25μm)分离,质谱检测,外标法定量。结果表明,丙酸在0.1~20.0μg/mL响应呈现良好线性,相关系数为1.000。方法加标回收率为83%~109%,相对标准偏差<7%,检出限为0.450 mg/kg。该方法前处理操作简便,检测快速、灵敏、准确度高。

A gas chromatography-mass spectrometry using liquid-liquid extraction combined with dual enzymatic hydrolysis for determination of propionic acid in cakes was developed successfully.The sample was hydrolyzed in phosphate buffer at 37℃to remove protein and starch.Propionic acid was converted to ionic state while the pH of hydrolyzed solution was adjusted to pH>10.Non-polar impurities were removed by ether extraction.Propionic acid was converted to molecular state by adjusting the aqueous phase pH<4.The propionic acid was extracted by ethyl acetate in order to remove polar impurities.The target analyte were separated on DB-WAX capillary column(30 m×0.25 mm,0.25μm),and detected by gas chromatography-mass spectrometry.The results indicated that the calibration curve for propionic acid was linear in the range of 0.1-20μg/mL with the correlation coefficient of 1.000.The spike recoveries were 83%-109%,RSD<7%.The detection limit was 0.450 mg/kg.The developed method has the advantages of simple pretreatment,high sensitivity,accuracy and fast.