Gil Raúl A, Gásquez José A, Olsina Roberto, Martinez Luis D, Cerutti Soledad
Area de Química Analítica, Facultad de Química Bioquímica y Farmacia, Universidad Nacional de San Luis, Chacabuco y Pedernera, San Luis, C.P. 5700, Argentina.
Talanta. 2008 Jul 30;76(3):669-73. doi: 10.1016/j.talanta.2008.04.004. Epub 2008 Apr 12.
A novel method for cobalt preconcentration by cloud point extraction with on-line phase separation in a PTFE knotted reactor and further determination by electrothermal atomic absorption spectrometry (ETAAS) is proposed. The cloud point system was formed in the presence of non-ionic micelles of polyethyleneglycolmono-p-nonylphenylether (PONPE 7.5) and it was retained on the inner walls of a knotted reactor (KR). The surfactant rich-phase was removed from the knotted reactor with 75 microL of methanol acidified with 0.8 mol L(-1) nitric acid, directly into the dosing hole of the L'Vov graphite tube. An enrichment factor of 15 was obtained with a preconcentration time of 60 s, with respect to the direct determination of cobalt by ETAAS in aqueous solutions. The value of the detection limit for the preconcentration of 5 mL of sample solution was 10 ng L(-1). The precision, expressed as the relative standard deviation (R.S.D.), for 10 replicate determinations at 0.5 microg L(-1) Co level was 4.5%. Verification of the accuracy was carried out by analysis of a standard reference material (NIST SRM 1640e "Trace elements in natural water"). The method was successfully applied to the determination of cobalt in drinking water samples.
提出了一种在聚四氟乙烯打结反应器中通过浊点萃取结合在线相分离进行钴预富集，并用电热原子吸收光谱法（ETAAS）进一步测定的新方法。在聚乙二醇单对壬基苯基醚（PONPE 7.5）的非离子胶束存在下形成浊点体系，并保留在打结反应器（KR）的内壁上。用75 μL用0.8 mol L⁻¹硝酸酸化的甲醇将富含表面活性剂的相从打结反应器中直接转移至L'Vov石墨管的进样孔中。与在水溶液中直接用ETAAS测定钴相比，预富集时间为60 s时获得了15倍的富集因子。对5 mL样品溶液进行预富集的检测限为10 ng L⁻¹。在0.5 μg L⁻¹钴水平下进行10次重复测定，以相对标准偏差（R.S.D.）表示的精密度为4.5%。通过分析标准参考物质（NIST SRM 1640e“天然水中的微量元素”）来验证准确性。该方法成功应用于饮用水样品中钴的测定。
