固相萃取-超滤离心-离子色谱法测定冰淇淋和雪糕中的硫氰酸盐

Determination of thiocyanate in icecream by SPE-ultrafiltration centrifugation-ion chromatography

目的建立冰淇淋和雪糕中硫氰酸盐的离子色谱测定方法。方法将样品融化混匀,用乙腈沉淀蛋白,上层样液在4℃下冷冻离心后,取上清液用固相萃取On GuardⅡRP柱过滤后超滤离心,超滤液直接用离子色谱仪进行测定。采用Ion PacAS16型分析柱进行分离,用ASRS-ULTRAⅡ型阴离子抑制器、KOH淋洗液进行梯度洗脱,ED50型电导检测器进行检测,以外标法定量。结果硫氰酸盐的标准曲线在0.10 mg/L^2.0 mg/L时呈现良好的线性关系,其线性方程为y=0.192x-0.015,相关系数r=0.999 2。该方法得到的硫氰酸盐的检出限为0.30 mg/kg,定量限为0.99 mg/kg,回收率为94.5%~103.6%,相对标准偏差RSD为1.4%~2.6%。结论本方法样品前处理的净化效果好,准确可靠,适用于冰淇淋和雪糕中硫氰酸盐的检测。

Objective To establish a method for the determination of thiocyanate in icecream by ion chromatography. Methods The samples were melted and mixed, and then added into acetonitrile to precipitated protein. The supernatant was frozen centrifuged at 4℃. The supernatant was filtered by SPE OnGuard II RP column, and then centrifuged with uhrafiltration device. The filtrate was detected by ion chromatography. The separation was carried out on IonPae AS16 column with ASRS - ULTRA II anion suppressor, and detected by ED50 conductivity detector. The gradient eluent was KOH. And the results was detected with ED50 electric conduction detector. The method was quantified by external standard. Results The thioeyanate standard curve showed good linear relationship in the range of 0. 10 mg/L - 0. 20 mg/L, with the correlation coefficient r = 0.999 2（y =0. 192x -0.015）. The detection limit was O. 30 mg/kg, and the quantification limit was 0.99 mg/kg. The recov- eries rates ranged from 94.5% to 103.6% , and RSD was among 1.4% - 2.6%. Conclusion The samples were better puri- fied in this method. The method was accurate and suitable for the determination of thiocyanate in icecream.