On-line separation and preconcentration of trace cadmium in environmental water samples by micro column filled with modified nanometer Si-HAP prior to FAAS determination

A novel method of on-line solid phase extraction (SPE) preconcentration has been established for the determination of cadmium in environmental water samples by flame atomic absorption spectrometry (FAAS). The method is based on the on-line retention of cadmium on a micro column of nanometer Silicon Hydroxyapatite (Si-HAP) modified with 1-phenyl-3-methyl-4-bonzoil-5-pyrazone (PMBP) and subsequent elution with 1.0M thiourea and determination by FAAS. The effect of various parameters that could affect the performance of the system was investigated. The enrichment factor (EF) for cadmium (II) was 250. The limit of detection (LOD) obtained under optimum conditions was 0.28 mu g L-1 and the relative standard deviation (RSD) for seven replicates at 100 mu g L-1 Cd2+ concentration level was 1.4%. The method was applied to water samples and standard reference materials. The accuracy was assessed through recovery experiments and comparing the results with the accepted values of standard reference material.