紫外分光光度法测定食糖中的硝酸盐含量

建立了检测食糖中硝酸盐含量的紫外分光光度法。食糖样品加入氨缓冲溶液超声提取后,经活性炭脱色,加入亚铁氰化钾溶液和乙酸锌溶液沉淀蛋白质和脂肪等杂质,在紫外分光光度计中波长220nm和275 nm处通过标准曲线法进行比较定量。该方法在10~200μg线性良好(R2=0.9997),检出限为1.875 mg/kg,分别在样品中添加硝酸钠标准品进行3个水平加标回收实验(3、30、100 mg/kg),回收率范围为92.8%~96.8%,相对标准偏差为1.5%~3.1%(n=6)。该方法样品前处理简单、快速,灵敏度、准确度和精密度均满足食糖中硝酸盐的检测要求。

Determination of Nitrate in Sugar by UV Spectrophotometry

A method was developed for the determination of nitrate in sugar by UV spectrophotometry. The sugar samples were extracted by ultrasonic with ammonia buffer solution, decolored with activated carbon, precipitated with potassium ferrocyanide and zinc acetate for protein, fat and other impurities and then detected by UV spectrophotometer at 220 nm and 275 nm. There was a good linear relationship between the absorbance and the content of nitrate in the range of 10~200μg (R2=0.9997). The limit of detection (LOD) was 1.875 mg/kg. The recoveries at three levels of 3, 30 and 100 mg/kg were from 92.8% to 96.8% and the relative standard deviation (RSD) of 1.5%~3.1% (n=6), respectively. The method is simple,rapid and characterized with acceptable sensitivity, accuracy and precision to meet the requirements of nitrate analysis in sugar.