Nascentes Clésia C, Arruda Marco Aurélio Z
Instituto de Química, Universidade Estadual de Campinas-Unicamp, PO Box 6154, 13084-862 Campinas SP, Brazil.
Talanta. 2003 Dec 23;61(6):759-68. doi: 10.1016/S0039-9140(03)00367-9.
A new micelle-mediated phase separation of metal ions, applied for preconcentrating trace levels of cobalt as a prior step to its determination by flame atomic spectroscopy, has been developed. Two methods were proposed employing both Triton X-100 and sodium dodecyl sulfate (SDS) as a mixed micellar system while the phase separation was induced by HCl or NaCl addition. Cobalt was complexed with pyridylazo compounds (PAN, PAR, 5-Br-PADAP) in an aqueous surfactant medium and it was concentrated in the surfactant rich phase after phase separation. The chemical variables affecting the cloud point extraction were evaluated, optimized and successfully applied to cobalt determination in pharmaceutical samples. Under the optimized conditions, the preconcentration system permitted limits of detection as 1.1 and 1.6 mug l(-1) cobalt, respectively, when HCl and NaCl were used. Both proposed methods showed linear calibration within a 25-200 mug l(-1) cobalt range. The extraction efficiency was investigated at different cobalt concentrations (40-185 mug l(-1)) and good recoveries (98-102%) were obtained by using NaCl as electrolyte. The results obtained were compared with those observed with ET AAS.
已开发出一种用于金属离子的新型胶束介导相分离方法，该方法用于在通过火焰原子光谱法测定钴之前对痕量钴进行预富集。提出了两种方法，采用 Triton X - 100 和十二烷基硫酸钠（SDS）作为混合胶束体系，同时通过添加 HCl 或 NaCl 诱导相分离。钴在水性表面活性剂介质中与吡啶偶氮化合物（PAN、PAR、5 - Br - PADAP）络合，相分离后在富含表面活性剂的相中富集。评估并优化了影响浊点萃取的化学变量，并成功应用于药物样品中钴的测定。在优化条件下，当使用 HCl 和 NaCl 时，预富集系统对钴的检测限分别为 1.1 和 1.6 μg l⁻¹。两种方法在 25 - 200 μg l⁻¹ 的钴范围内均显示出线性校准。在不同钴浓度（40 - 185 μg l⁻¹）下研究了萃取效率，使用 NaCl 作为电解质时获得了良好的回收率（98 - 102%）。将所得结果与用石墨炉原子吸收光谱法（ET AAS）观察到的结果进行了比较。
