反相色谱和离子交换色谱测定三聚氰胺氰尿酸中三聚氰胺与硫脲的对比研究

Comparative investigation on determination of melamine and thiourea in melamine-cyanuric acid complex by reversed phase liquid chromatography and ion exchange chromatography

分别采用反相色谱和离子交换色谱检测三聚氰胺氰尿酸(MCA)中三聚氰胺和硫脲,并对检测方法进行了对比研究。实验分别使用盛瀚SH-CC-4柱,流动相为甲醇∶5mmol·L^-1甲基磺酸(10∶90,V∶V)和AgilentTC-C18柱,流动相为乙腈∶5mmol·L^-1醋酸铵(3∶97,V∶V)为流动相对其进行分离,紫外检测。结果表明,反相色谱法中三聚氰胺在0.5~8.0mg·L^-1范围内线性关系良好,相关系数R2为0.9995,检测限和定量限分别为2.2×10^-3 mg·L^-1和7.5×10^-3 mg·L^-1,方法精密度(重复性)RSD=1.41%(n=7),样品回收率91.3%。硫脲在0.05-0.8mg·L^-1范围内线性关系良好,相关系数R2为0.9993,检测限和定量限分别为2×10^-4 mg·L^-1和7×10^-4 mg·L^-1,方法精密度(重复性)RSD=0.68%(n=7),离子交换色谱法峰形对称,三聚氰胺在0.5~8.0mg·L^-1范围内线性关系良好,相关系数R2为0.999,检测限和定量限分别为1.7×10^-3 mg·L^-1、6.1×10^-3mg·L^-1,分析方法(重现性)RSD=1.12%(n=11),样品回收率95.8%,硫脲在0.5~8.0mg·L^-1范围内线性关系良好,相关系数R2为0.999,检测限和定量限分别为1.6×10^-3 mg·L^-1和5.1×10^-3 mg·L^-1,方法精密度(重复性)RSD=1.5%(n=5)对测定结果的F检验(方法精密度)表明两者无显著性差异,但t检验(方法系统误差)表明两者有显著差异。两种方法均能较好地对样品中的三聚氰胺和硫脲进行定性和定量分析,但两者存在系统误差,原因需进一步探索。

The separations of melamine and thiourea from melamine cyanuric acid(MCA)were performed on a Shenghan SH-CC-4 cation-exchange column with methanol∶5 mmol·L^-1 methanesulfonic acid(10∶90,v/v)as eluent and on a Agilent TC-C18 column with acetonitrile and 5 mmol·L^-1 ammonium acetate(3∶97,v/v)as eluent.In case of RPLC method,the obtained calibration plots for melamine and thiourea had excellent regression coefficients(R2=0.9995 and R2=0.9993,correspondingly)in the concentration range of 0.50—8.0 mg·L^-1.The limits of detection(LOD)and the limits of quantification(LOQ)of melamine were 2.2×10^-3 mg·L^-1 and 7.5×10^-3 mg·L^-1,respectively.The reproducibility of detection(n=7),RSD,was less than 1.41%,and the recovery was over 91.3%.The LOD and LOQ values of thiourea were 2×10^-4 mg·L^-1 and 7×10^-4 mg·L^-1,respectively.The reproducibility of detection(n=7),RSD,was less than 0.68%.In case of IC method,calibration plot for melamine exhibited excellent regression(R2=0.999)in the range of 0.5—8.0 mg·L^-1.The LOD and LOQ values were 1.7×10^-3 mg·L^-1 and 6.1×10^-3 mg·L^-1,respectively.The reproducibility of detection(n=11),RSD,was less than 1.12%,and the recovery was over 95.8%.Thiourea exhibited excellent regression(R2=0.999)in the range of 0.5—8.0μg/mL.The LOD and LOQ values were 1.6×10^-3 mg·L^-1 and 5.1×10^-3 mg·L^-1,respectively.The reproducibility of detection(n=5)was less than 1.5%.The F-test results showed there was no significant difference between the two methods,while the t-test results showed there was significant difference between them.The result of methodological study demonstrated that both methods can be used to analyze melamine and thiourea in the samples with comparable analytical parameters.