水发食品中甲醛现场测定的样品快速前处理新方法研究

A Novel Method of Fast Sample Pretreatment for in situ Determination of Formaldehyde in Water-soaked Foodstuffs

提出了一种用于现场测定水发食品中甲醛含量的样品快速前处理新方法,采用乙酸锌和亚铁氰化钾沉淀样品中的蛋白质和脂肪,在弱酸性介质和沸水浴条件下提取了样品中的甲醛,并与乙酰丙酮立即发生显色反应.研究了不同样品前处理方法对甲醛提取和测定的影响,探讨了水发食品中的甲醛本底值及其是否被人为添加甲醛的判断标准.此方法的特点是样品前处理与显色反应同时进行,在10 m in内即可完成对水发食品中甲醛含量的定量测定.

A simple, rapid method for sample preparation for in situ determination of formaldehyde in watersoaked foodstuffs was developed. The advantage of this method is that the sample pretreatment and the color reaction can be finished simultaneously. The protein and the fatty compounds in the sample are precipitated by zinc acetate and potassium ferrocyanide, then the chromogenic reaction of acetylacetone with formaldehyde released from the sample in weak-acid medium and boiling bath takes place immediately. Various experimental parameters were studied and optimized, so the analysis of each sample can be completed in 10 min. More than 100 kinds of practical samples were analyzed. The results were in good agreement with those obtained by the standard method, and the relative errors of determined values were less than 5 % if the formaldehyde concentrations were more than 10 mg/kg. The background concentration of formaldehyde in practical samples and the standard for judging samples containing spiking formaldehyde were studied. The determined values less than mg/kg were regarded as the background concentration of formaldehyde in samples, and the determined values more than 20 mg/kg were regarded as the evidences that the samples contained spiking formaldehyde.