离子色谱法测定鲜乳与乳制品中的亚氯酸盐和氯酸盐

Determination of chlorite and chlorate in milk and dairy products by ion chromatography

目的建立鲜乳与乳制品中的亚氯酸盐和氯酸盐的离子色谱测定方法。方法液态奶、奶饮品和奶粉样品经过乙腈沉淀蛋白,RP柱去除脂肪等疏水性化合物后,采用Ion Pac AS19分析柱(250 mm×4 mm)和Ion Pac AG19保护柱(50 mm×4 mm)分离,EGC在线产生KOH梯度淋洗,电导法测定氯酸盐,串联柱后衍生间接紫外法测定亚氯酸盐,检测波长为352 nm,外标法定量。结果亚氯酸盐、氯酸盐的浓度为0.05 mg/L^1.0 mg/L时,线性关系良好,相关系数(r)分别为0.999 5和0.999 8;方法的检出限(S/N=3)分别为0.001 mg/L和0.010 mg/L;相对标准偏差(RSD)分别为3.1%和2.5%(n=6),加标回收率分别为70.0%~92.4%、87.5%~108.6%。结论该方法具有灵敏度高、准确性好、抗干扰强的特点,能满足乳与乳制品中痕量亚氯酸盐和氯酸盐的测定。

Objective To establish a method for determination of chlorite and chlorate in milk and dairy products by ion chromatography. Methods After the protein in sample were precipitated with acetonitrile,fat and other hydrophobic compounds in sample were removed with RP column. The separation was carried out by Ion Pac AS19（ 250 mm × 4 mm） and Ion Pac AG19 guard column（ 50 mm × 4 mm）,using gradient eluent of KOH generated from the on- line EGC. Chlorate was determined by electrical conductivity method; indirect UV method derived from tandem columns was used to determine the chlorite,the detection wavelength was 352 nm,and the external standard method was used for quantitative analysis. Results The linear relationship was good,and the correlation coefficients（ r） were 0. 999 8 and 0. 999 5,respectively,when the concentration of the chlorite and chlorate was between 0. 05 mg / L- 1. 0 mg / L. The detection limits（ S / N = 3） of chlorite and chlorate were 0. 001 mg /L and 0. 010 mg / L,respectively. The relative standard deviations（ RSD） were 3. 1% and 2. 5%（ n = 6）,and the recoveries were among 70. 0%- 92. 4% and 87. 5%- 108. 6%. Conclusion The method possesses the advantages of good sensitivity,accuracy and strong anti- interference,and it is suitable for the determination of trace chlorite and chlorate in milk and dairy products.