SIMULTANEOUS DETERMINATION OF TRACE AMOUNTS OF COPPER, NICKEL AND VANADIUM IN SEA-WATER BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY AFTER EXTRACTION AND BACK-EXTRACTION

A method for the simultaneous determination of Cu, Ni and V in sea-wat er by HPLC is described. The complexes of these metals with 2-(5-bromo -2-pyridylazo)-5-(N-propyl- N-sulfopropylamino)-phenol (5-Br-PAPS) are extracted with capriquat (trioctylmethylammonium chloride) in xylene and back-extracted into sodium perchlorate solution followed by separa tion and determination by HPLC with an octadecylsilane column and spec trophotometric detection. The conditions of extraction and back-extrac tion such as, pH, concentration of 5-Br-PAPS or capriquat and concentr ation of sodium perchlorate are investigated. Linear calibration;curve ranges, limits of detection and interferences owing to other ions in sea-water are presented. Application of this method to the trace analy sis of Cu, Ni and V in sea-water is demonstrated.