solid phase extraction of trace copper in aqueous samples using c18 membrane disks modified by benzildithiosemicarbazone prior to flame atomic absorption spectrometric (faas) determination

a highly convenient, selective and sensitive procedure for pre-concentration, separation and determination of sub-ppm levels of cu 2+ in aqueous samples based on modification of octadecyl silica bonded phase membrane (osbpm) disks is described using benzildithiosemicarbazone  (bdsc) as a powerful modifier. it was revealed that each loaded osbpm disk with 6.0 mg of bdsc serves as excellent bead for trapping, enrichment and isolation of trace copper. the analyte was trapped during introduction the aqueous solutions through the surface of each modified membrane, quantitatively, while other interfering ions passed through the disk to drain. the adsorbed cu 2+ ions were then stripped by appropriate eluting agents followed by monitoring of the eluates by faas. the effects of sample ph, amount of the modifier, stripping agent types and sample flow-rates were also investigated. the described method permitted a pre-concentration factor of about 200. the detection limit of the procedure was predicted to be about 0.013 ng l -1 . the method was successfully employed for recovery and quantification of trace copper in different water samples.