Padarauskas A, Judzentiene A, Naujalis E, Paliulionyte V
Department of Analytical Chemistry, Vilnius University, Lithuania.
J Chromatogr A. 1998 May 29;808(1-2):193-9. doi: 10.1016/s0021-9673(98)00118-6.
A method for on-line chromatographic preconcentration and determination of chromium(VI) traces has been developed. Chromate was preconcentrated on a C18 column (50 x 6 mm I.D.) after complexation with diphenylcarbazide (DPC). Following the preconcentration step, analysis of the sample was performed using a C18 column (100 x 6 mm I.D.) with an eluent containing 6.10(-3) mol/l sulphuric acid and 20% (v/v) acetonitrile. Direct spectrophotometric detection at 546 nm was used. Experimental parameters such as mobile phase pH, DPC concentration, preconcentration flow-rate, sample volume were optimized for preconcentration and detection of Cr(VI)-DPC complex. Under the optimum conditions, most metal ions [Cr(III), Fe(III), Cu(II), Hg(II), Mo(VI), V(V)] and inorganic anions did not interfere. A detection limit of 0.02 ng/ml Cr(VI) can be attained when a sample volume of 100 ml is used. The technique has been applied successfully to the determination of Cr(VI) traces in drinking, surface and groundwater samples and the recoveries of added chromium were in the range 94-104%.
已开发出一种在线色谱预浓缩和测定痕量铬（VI）的方法。铬酸盐在与二苯卡巴肼（DPC）络合后，在C18柱（内径50×6 mm）上进行预浓缩。预浓缩步骤之后，使用内径为100×6 mm的C18柱，以含有6×10⁻³ mol/l硫酸和20%（v/v）乙腈的洗脱液对样品进行分析。采用在546 nm处直接分光光度检测。对流动相pH值、DPC浓度、预浓缩流速、样品体积等实验参数进行了优化，以用于铬（VI）-DPC络合物的预浓缩和检测。在最佳条件下，大多数金属离子[铬（III）、铁（III）、铜（II）、汞（II）、钼（VI）、钒（V）]和无机阴离子不产生干扰。当使用100 ml样品体积时，铬（VI）的检测限可达0.02 ng/ml。该技术已成功应用于饮用水、地表水和地下水样品中痕量铬（VI）的测定，添加铬的回收率在94%至104%之间。
