分光光度法测定乳与乳制品中硫氰酸钠的含量

Spectrophotometric determination of sodium thiocyanate in milk and milk powder

研究了硫酸铁铵分光光度法测定乳与乳制品中硫氰酸钠的含量。方法:样品加三氯乙酸溶液和双氧水溶液置60℃水浴进行蛋白沉淀后,过滤,取滤液加硝酸酸化,再用硫酸铁铵溶液进行显色,在465nm处测定其吸光值,用标准曲线法测其含量。结果:本方法的线性范围为1.00mg/L^20.0mg/L,以吸光值0.02作为检出限,则液体的检出限为3mg/L、固体的检出限为6mg/kg,奶粉和鲜奶的相对标准偏差分别为3.80%和2.43%,本方法回收率在98.6%~99.7%之间。检测结果与离子色谱法检测结果比较的相对偏差均在10%以内。鉴于显色稳定性,方法要求标准溶液和样品溶液显色后分别在15min和30min内完成检测。本方法具有操作简便,结果准确等优点,对乳与乳制品中硫氰酸钠的控制具有重要意义。因本方法使用的紫外分光光度仪非常普及,很适合在广大中小企业推广。

This paper describes the method for spectrophotometric determination of sodium thiocyanate in milk and milk powder.Method：The sample protein was precipitated by trichloroacetic acid in water bath at 60℃.Nitric acid was used in filtrated liquid acidification and ammonium ferric sulfate was used for a color reaction.Then the solution was detected at 465nm.Liner relationship between values of absorbance and mass concentration of sodium thiocyanate were obtained in the range of 1.00-20.0mg/L,with detection limit of 3mg/L in milk and 6mg/kg in milk powder.The RSD（n=7） was 3.80% in milk power and 2.43% in milk.The recovery was 98.6%-99.7%.The standard deviation of this method and ionization chromatography were both less then 10%.The method required detection that must be finished at 15 minutes and 30 minutes after color development.This method was simple and accurate and showed significance in controlling sodium thiocyanate levels in milk and milk powder.This method is very suitable for industrial applications.