COUPLING OF FLOW-INJECTION WETTING-FILM EXTRACTION WITHOUT SEGMENTATION AND PHASE-SEPARATION TO FLAME ATOMIC-ABSORPTION SPECTROMETRY FOR THE DETERMINATION OF TRACE COPPER IN WATER SAMPLES

A flow injection wetting-film extraction system without segmentor and phase separator has been coupled to flame atomic absorption spectromet ry for the determination of trace copper. Isobutyl methyl ketone (MIBK ) was selected as coating solvent and 8-hydroxyquinoline (oxine) as th e chelating reagent. By switching of a 8-channel valve and alternative initiation of two peristaltic pumps, MIBK, sample solution containing copper chelate of oxine, and air-segment sandwiched eluting solution (1.0 mol l(-1) nitric acid) were sequentially aspirated into an extrac tion coil made of PTFE tubing of 360 cm length and 0.5 mm i.d. The for mation of organic film in the wall of the extraction coil, extraction of the copper chelate into the organic film and back-extraction of the analyte into the eluting solution occurred consecutively when these z ones aspirated into the extraction coil were propelled down the extrac tion coil by a carrier solution at a flow rate of 2 ml min(-1). After leaving the extraction coil, the concentrated zone was transported to the nebulizer at its free uptake rate for atomization. Under the optim ized conditions, an enrichment factor of 43 and a detection limit of 0 .2 mu g l(-1) copper were achieved at a sample throughput rate of 30 h (-1). Eleven determinations of a standard copper solution of 60 mu g l (-1) gave a relative standard deviation of 1.5%. Foreign ions possibly present in tap water and natural water did not interfere with the cop per determination. The developed method has been successfully used to the determination of copper content of tap water and river water. (C) 1998 Elsevier Science B.V. All rights reserved.