Ortega Claudia, Cerutti Soledad, Olsina Roberto A, Martínez Luis Dante, Silva María Fernanda
Area de Química Analítica, Universidad Nacional de San Luis, Chacabuco y Pedernera, San Luis 5700, Argentina.
J Pharm Biomed Anal. 2004 Nov 19;36(4):721-7. doi: 10.1016/j.jpba.2004.08.027.
Automated preconcentration strategies are needed when analyzing metals in real samples by capillary electrophoresis (CE) with UV detection. The on-line incorporation of cloud point extraction (CPE) to flow injection analysis (FIA) associated with CE for simultaneously determining dysprosium and iron at ppb levels in urine is presented and evaluated for the first time. The preconcentration step is mediated by micelles of the non-ionic surfactant polyethyleneglycol-mono-p-nonylphenylether (PONPE 7.5) with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol. The micellar system containing the complex was loaded into the FIA manifold at a flow rate of 8 mlmin(-1), and the surfactant rich-phase was retained in a microcolumn packed with cotton, at pH 9.2. The surfactant-rich phase was eluted with 50 microl acetonitrile directly into the CE sample vial, allowing to reach an enrichment factor of 200-fold for a 10 ml sample urine. The type and composition of the background electrolytes (BGE) were investigated with respect to separation selectivity, reproducibility and stability. A BGE of 20mM sodium tetraborate buffer containing 13% acetonitrile, pH 9.0 was found to be optimal for the separation of metal chelates. Detection was performed at 585 nm. An enhancement factor of 200 was obtained for the preconcentration of 10 ml of sample solution. The detection limits for the preconcentration of 10 ml of urine were 0.20 microgl(-1) for Dy, and. 0.48 microgl(-1) for Fe. The calibration graphs using the preconcentration system were linear with a correlation coefficient of 0.9989 (Dy) and 0.9976 (Fe) at levels near the detection limits up to at least 500 microgl(-1). The method was successfully applied to the determination of dysprosium and iron in urine for monitoring the elimination of dysprosium-based pharmaceuticals.
在通过紫外检测的毛细管电泳（CE）分析实际样品中的金属时，需要自动化预浓缩策略。首次提出并评估了将浊点萃取（CPE）在线引入与CE相关的流动注射分析（FIA）中，用于同时测定尿液中ppb水平的镝和铁。预浓缩步骤由非离子表面活性剂聚乙二醇单对壬基苯基醚（PONPE 7.5）与2-(5-溴-2-吡啶偶氮)-5-二乙氨基苯酚的胶束介导。含有该络合物的胶束体系以8 mlmin(-1)的流速加载到FIA流路中，富表面活性剂相保留在填充有棉花的微柱中，pH为9.2。用50微升乙腈将富表面活性剂相直接洗脱到CE样品瓶中，对于10毫升尿样，富集倍数可达200倍。研究了背景电解质（BGE）的类型和组成对分离选择性、重现性和稳定性的影响。发现含有13%乙腈、pH 9.0的20 mM四硼酸钠缓冲液作为BGE对金属螯合物的分离最为理想。检测在585 nm处进行。10毫升样品溶液预浓缩的增强因子为200。10毫升尿液预浓缩的检测限为：镝0.20 microgl(-1)，铁0.48 microgl(-1)。使用预浓缩系统得到的校准曲线在接近检测限直至至少500 microgl(-1)的水平上呈线性，镝的相关系数为0.9989，铁的相关系数为0.9976。该方法成功应用于尿液中镝和铁的测定，以监测基于镝的药物的排泄情况。
