Anthemidis Aristidis N, Ioannou Kallirroy-Ioanna G
Laboratory of Analytical Chemistry, Department of Chemistry, Aristotle University, Thessaloniki 54124, Greece.
Talanta. 2009 Jun 30;79(1):86-91. doi: 10.1016/j.talanta.2009.03.005. Epub 2009 Mar 14.
A simple, sensitive and powerful on-line sequential injection (SI) dispersive liquid-liquid microextraction (DLLME) system was developed as an alternative approach for on-line metal preconcentration and separation, using extraction solvent at microlitre volume. The potentials of this novel schema, coupled to flame atomic absorption spectrometry (FAAS), were demonstrated for trace copper and lead determination in water samples. The stream of methanol (disperser solvent) containing 2.0% (v/v) xylene (extraction solvent) and 0.3% (m/v) ammonium diethyldithiophosphate (chelating agent) was merged on-line with the stream of sample (aqueous phase), resulting a cloudy mixture, which was consisted of fine droplets of the extraction solvent dispersed entirely into the aqueous phase. By this continuous process, metal chelating complexes were formed and extracted into the fine droplets of the extraction solvent. The hydrophobic droplets of organic phase were retained into a microcolumn packed with PTFE-turnings. A portion of 300 microL isobutylmethylketone was used for quantitative elution of the analytes, which transported directly to the nebulizer of FAAS. All the critical parameters of the system such as type of extraction solvent, flow-rate of disperser and sample, extraction time as well as the chemical parameters were studied. Under the optimum conditions the enhancement factor for copper and lead was 560 and 265, respectively. For copper, the detection limit and the precision (R.S.D.) were 0.04 microg L(-1) and 2.1% at 2.0 microg L(-1) Cu(II), respectively, while for lead were 0.54 microg L(-1) and 1.9% at 30.0 microg L(-1) Pb(II), respectively. The developed method was evaluated by analyzing certified reference material and applied successfully to the analysis of environmental water samples.
开发了一种简单、灵敏且强大的在线顺序注射（SI）分散液液微萃取（DLLME）系统，作为在线金属预富集和分离的替代方法，使用微升体积的萃取溶剂。将这种新型方案与火焰原子吸收光谱法（FAAS）联用，展示了其在测定水样中痕量铜和铅方面的潜力。含有2.0%（v/v）二甲苯（萃取溶剂）和0.3%（m/v）二乙基二硫代磷酸铵（螯合剂）的甲醇（分散剂溶剂）流与样品流（水相）在线合并，形成浑浊混合物，该混合物由完全分散在水相中的萃取溶剂细滴组成。通过这个连续过程，形成金属螯合络合物并萃取到萃取溶剂的细滴中。有机相的疏水液滴保留在填充有聚四氟乙烯细屑的微柱中。使用300微升异丁基甲基酮对分析物进行定量洗脱，然后直接输送到FAAS的雾化器中。研究了系统的所有关键参数，如萃取溶剂类型、分散剂和样品的流速、萃取时间以及化学参数。在最佳条件下，铜和铅的富集因子分别为560和265。对于铜，在2.0微克/升Cu（II）时，检测限和精密度（相对标准偏差）分别为0.04微克/升和2.1%，而对于铅，在30.0微克/升Pb（II）时，检测限和精密度分别为0.54微克/升和1.9%。通过分析有证标准物质对所开发的方法进行了评估，并成功应用于环境水样的分析。
