梯度淋洗/离子色谱法测定婴儿乳粉中硝酸盐

Determination of nitrate in infant milk powder using gradient elution/Ion chromatography

婴儿乳粉中含有丰富的营养物质,存在干扰硝酸盐分析的未知成分。采用梯度淋洗方式将其与硝酸盐进行分离,达到了准确测定的目的。分析过程中采用乙酸溶液沉淀乳乳粉中蛋白,过滤后用RP柱去除样品中的脂类物质。净化后,直接将试样注入离子色谱仪分析,淋洗液由自动发生器产生,外标法定量。稳定性实验5次进样硝酸盐的峰面积平均值为0.2961μS.min(RSD为0.35%),保留时间平均值为26.721 min(RSD为0.23%)。组分添加回收率分别为99.04%和99.43%,相对偏差(RSD)分别为1.85%和1.02%。

Infant milk powder is very rich in nutrients,there is interference with nitrate analysis of unknown composition.In this paper,gradient elution method separate it nitrate to the accurate determination of purpose.It was found that the solution of acetic acid for milk protein precipitation and filtration column followed by RP removal of lipid material samples.After purification,the sample directly was analyzed by the ion chromatograph,the volume of external standard.Stability test sample 5 times of the peak area nitrate average were 0.2961μS·min（RSD 0.35%）,the average retention time was 26.721min（RSD 0.23%）.Component recoveries were 99.04% and 99.43%,RSD were 1.85% and 1.02%.