Luconi Marta O, Olsina Roberto A, Fernández Liliana P, Silva M Fernanda
Area de Química Analítica, Universidad Nacional de San Luis, Chacabuco y Pedernera, San Luis 5700, Argentina.
J Hazard Mater. 2006 Feb 6;128(2-3):240-6. doi: 10.1016/j.jhazmat.2005.08.007. Epub 2005 Nov 17.
A micelle-mediated phase separation without added chelating agents to preconcentrate trace levels of lead in human saliva as a prior step to its determination by capillary electrophoresis has been developed. The enrichment step is based on the cloud point extraction of lead with the non-ionic surfactant PONPE 7.5 in the absence of chelating agent. The surfactant-rich phase was diluted with acetonitrile and the resultant solution was injected directly into the CE instrument. Factors affecting the combined methodology such as surfactant-rich phase diluting agent, buffer pH and concentration, applied voltage, sample preparation and presence of additives were studied in detail. A BGE of 20 mM imidazole containing 30% acetonitrile, pH 6.20 was found to be optimal for the separation of lead from other saliva constituents. Indirect detection was performed at 205 nm. The detection limit value of lead for the preconcentration of 8 ml of saliva was 11.4 microg l(-1). The calibration graph using the preconcentration system was linear with a correlation coefficient of 0.997 at levels near the detection limits up to at least 400 microg l(-1). The reproducibility (R.S.D.) on the basis of migration time and peak area were better than 0.68 and 3.6%, respectively. The method was successfully applied to the determination of lead in human saliva.
已开发出一种胶束介导的相分离方法，该方法无需添加螯合剂即可对人唾液中的痕量铅进行预富集，作为通过毛细管电泳测定铅的前期步骤。富集步骤基于在不存在螯合剂的情况下，用非离子表面活性剂PONPE 7.5对铅进行浊点萃取。用乙腈稀释富含表面活性剂的相，并将所得溶液直接注入CE仪器。详细研究了影响该联合方法的因素，如富含表面活性剂相的稀释剂、缓冲液pH值和浓度、施加电压、样品制备以及添加剂的存在情况。发现含有30%乙腈、pH 6.20的20 mM咪唑缓冲液体系最适合从其他唾液成分中分离铅。在205 nm处进行间接检测。对8 ml唾液进行预富集时，铅的检测限为11.4 μg l(-1)。使用预富集系统的校准曲线在接近检测限的水平直至至少400 μg l(-1)范围内呈线性，相关系数为0.997。基于迁移时间和峰面积的重现性（相对标准偏差）分别优于0.68%和3.6%。该方法成功应用于人唾液中铅的测定。
