离子色谱-电导法同时测定奶粉中碘离子和硫氰酸根离子

Simultaneous determination of iodide ion and thiocyanate ion in powdered milk using ion chromatography with conductivity detection

采用离子色谱法建立了奶粉中微量碘离子和硫氰酸根离子同时定量分析的方法。样品采用乙酸冷藏法沉淀蛋白,超声波提取,上清液以On Guard RP小柱净化除杂。以高亲水阴离子交换色谱柱IonPac AS16柱为分析柱,KOH溶液梯度淋洗,电导检测器同时测定奶粉中微量碘离子和硫氰酸根离子,以外标法进行定量分析。结果表明,碘离子和硫氰酸根离子在5.0~200.0μg/L范围内线性关系良好,相关系数r>0.999,检出限分别为0.12mg/kg和0.09mg/kg,回收率、精密度良好。该方法操作简便,专属性强,线性良好,可以用于奶粉中碘离子和硫氰酸根离子的含量检测。

In this study,a quantitative analysis method of the concentration of iodide ion and thiocyanate ion in powdered milk was established by Ion Chromatography（IC）. Acetic acid frozen method was applied for protein precipitation of samples,ultrasonic wave method was applied for extraction,and On Guard RP column method was applied for further purification. Having Ion Pac AS16 column as the analysis column,gradient elution by KOH solution,the iodide ion and thiocyanate ion were simultaneously detected using a conductivity detector,while external standard method was used for quantitative analysis. Results and conclusions were drawn as follows ：First,iodide ion and thiocyanate ion had good linearity within limit of 5.0 to 200.0μg/L,and the correlative coefficient was over 0.999. Second,the LOQ of iodide ion and thiocyanate ion were approximately 0.12 mg/kg and 0.09 mg/kg,respectively. Finally,the method had good recovery rate and precision. The method was simple and convenient. It also had strong specificity and good linear relationship. It was very suitable for the determination of iodide ion and thiocyanate ion in powdered milk.