食品中微量甲醛的化学分析研究

比较研究了用比色方法快速检测食品中微量甲醛的两种方法:间苯三酚显色法和变色酸法。实验中发现,利用甲醛在碱性条件下与间苯三酚发生缩合反应的性质,可以生成橙红色化合物,但是产物的稳定性差,只适用于甲醛的定性分析;甲醛在浓硫酸介质中与变色酸发生特异性反应,可以生成稳定的紫色化合物,甲醛在0.00～2.4μg/mL的浓度范围内与吸光值呈线性关系,变异系数小于1%,分析的检测限为0.03μg/mL;添加甲醛于一些食品样品中测定其回收率发现,甲醛的平均添加回收率为42.8%,其原因可能是甲醛与食品中的蛋白质发生反应,从而在分析时测定出的游离甲醛量低于原先的添加量。最终结果表明,变色酸比间苯三酚更适合微量甲醛检测,并且具有简便、快速、灵敏的优点。

Formaldehyde is an important preservative, and it is also a very harmfu l material to human. Formaldehyde is forbidden to use in food as an additive in China. In this paper, chromotropic acid and phloroglucinol were employed to dete ct formaldehyde in some foods. It was found that formaldehyde reacted with phlor oglucinol in alkaline media and a salmon pink colored substance was formed there by.When formaldehyde reacted with chromotropic acid in condensed sulfuric acid, a stable purple substance was formed and no other compounds interfered this reac tion. It was found that formaldehyde could be detected as low as 0.13 靏/mL.Whe n formaldehyde content was in the range of 0.00～2.4靏/mL, the absorbance of re action mixture was proportional to formaldehyde content and with a relative stan dard error less than 1%. Therefore the reaction was suitable to be used in quant itative analysis of formaldehyde in foods.