食品中亚硫酸盐测定方法的改进

Improvenment of colorimetric determination of sulfites in foods

为改进GBT500934食品中亚硫酸盐的测定方法,进行了一系列的改进。SO2标准溶液的配制改为先测定固体试剂NaHSO3中SO2的纯度,而后根据已知的SO2纯度直接称取NaHSO3配成SO2标准溶液。显色剂中使用027%的甲醛溶液和015molL的盐酸溶液,显色剂用量10ml,最大吸收波长580nm。该试验除NO-2及S2-外,其他共存物质及添加剂等均无干扰,在样品溶液中加入H2O2作为校正空白消除反应过程中产生的呈色物质及背景颜色的干扰。改进后的方法SO2标准溶液的配制简捷,灵敏度是国标法的16倍,最小检出量为01μg,样品最低检测浓度为02mgkg,回收率为900%～1100%,RSD范围为05%～32%。反应速度、显色体系的稳定性及可操作性等大为提高。该方法适用于食品中SO2的测定。

Determination of traces of sulfites in various foods was attempted by using the modified para rosaniline formaldehyde colorimetry of the national standard GB/T 5009.34. The effects of preparation of sulfite standard solution, optimum condition of color reaction and coexistence substances on the determination of sulfites were investigated. The effects of interfering substances in samples and background color on the color reaction could be corrected by adding hydrogen peroxide directly into the sample solution before color development as subtraction of the sample blank. Using the modified technique, the sensitivity, specificity, reaction velocity, reproducibility and operability were all increased. The minimum detectable quantity of this method was 0 1 μg SO 2 in solution. The minimum detectable concentration was 0 2 mg/kg SO 2 in food samples. The method could be applied to almost all kinds of foods.