提出了气相色谱法测定豆瓣酱中山梨酸、苯甲酸、对羟基苯甲酸甲酯、对羟基苯甲酸乙酯、对羟基苯甲酸丙酯、对羟基苯甲酸丁酯共6种防腐剂含量的方法。豆瓣酱样品用乙醚提取,所得提取液须经凝胶色谱净化大分子干扰物质。方法中采用Biobeads S-X3凝胶渗透色谱净化柱和乙酸乙酯-环己烷(1+1)混合溶液作流动相,采用Rxi-17(0.25 mm×30 m,0.25 μm)毛细管柱分离后,用氢火焰离子化检测器检测。6种防腐剂的质量浓度均在10.0~400 mg·L-1范围内与峰面积呈线性关系,方法的检出限(3S/N)在0.56~0.74 mg·kg-1之间。在3个浓度水平下对方法的回收率和精密度进行了试验,测定回收率在91.4%~98.8%之间,相对标准偏差(n=5)在2.9%~5.3%之间。

A method of GC for determination of 6 preservatives, including sorbic acid, benzoic acid, methyl p-hydroxybenzoate, ethyl p-hydroxybenzoate, propyl p-hydroxybenzoate and butyl p-hydroxybenzoate, in bean paste was proposed. The sample was extracted with acetonitrile, and the extracts obtained were purified to remove the macromolecular impurities by gel permeation chromatography (GPC), using the Biobeads S-X3 GPC column and a mixed solvent of ethyl acetate and cyclohexane (1+1) as mobile phase. The 6 preservatives were separated on Rxi-17 (0.25 mm×30 m, 0.25 μm) capillary column and determined by FID detector. Linear relationships between values of peak area and mass concentration of the 6 preservatives were kept in the same range of 10.0-400 mg·L-1, with detection limits (3S/N) in the range of 0.56-0.74 mg·kg-1. Recovery and precision of the method were tested at 3 concentration levels, giving results of recovery in the range of 91.4%-98.8%, and RSD′s (n=5) in the range of 2.9%-5.3%.