DETERMINATION OF CADMIUM BY INDUCTIVELY COUPLED PLASMA ATOMIC EMISSION-SPECTROMETRY AFTER SUCTION-FLOW ONLINE PRECONCENTRATION ON 8-QUINOLINOL-LOADED ACTIVE-CARBON

The suction-flow on-line column preconcentration of cadmium from an aqueous solution for inductively coupled plasma atomic emission spectrometry (ICP-AES) was investigated utilizing a column packed with gas chromatographic-grade porous active-carbon impregnated with 8-quinolinol. A sample solution (pH 2.5 - 7) and a buffer solution were sucked, mixed and pumped through the column; subsequently, the analyte was eluted directly into the nebulizer of the ICP with 1 cm3 of 0.5 mol dm-3 hydrochloric acid. Using 5 cm3 of the sample solution, this method gave a signal enhancement of 1 order of magnitude for cadmium, better than that obtained by a conventional nebulization system; the detection limit was 0.25 ng cm-3 with a sampling rate of 35 h-1. The relative standard deviation for 500 ng cadmium was 1.1% (n = 10). This column could be used for more than 80 replicate analyses when 5 cm3 of a standard solution containing 100 ng cm-3 cadmium(II) was introduced into the system each time. The proposed method was applied to the determination of cadmium in certified biological reference materials.