On-line speciation of Cr(III) and Cr(VI) using microcolumn packed with immobilized used green tea leaves (UGTLs) and determination by ICP-OES in environmental water samples

摘要

A simple and sensitive method has been developed using microcolumn (20-mm length x 2.0 -mm i.d) packed with immobilized used green tea leaves (UGTLs) for the speciation of Cr(III) and Cr(VI) prior to their determination by inductively coupled plasma optical emission spectrometry (ICP-OES). The optimal experimental conditions including pH, eluent concentration and volume, sample volume and sample flow rate were investigated and established. The adsorption capacity of immobilized used green tea leaves for Cr(III) was found to be 35 mg g(-1). A preconcentration time of 72 s and an elution time of 8 s, with an enrichment factor of 10 and a sampling frequency of 20 h(-1), were obtained. The detection limit corresponding to three times the standard deviation of the blank was found to be 87 pg mL(-1). The precision for seven replicate determinations at the 2-ng mL(-1) level of Cr(III) gave a relative standard deviation (RSD) of 5%. The method was applied to the determination of Cr(III) and Cr(VI) in environmental water samples with satisfactory results.