Extraction of Trace Amounts of Copper(II) on a Membrane Filter Using 5,10,15,20-Tetraphenyl-21H,23H-porphinetetrasulfonic Acid for the Determination by Solid-Phase Spectrophotometry

Abstract

A highly sensitive solid-phase spectrophotometric method for the determination of trace amounts of copper(II) using 5,10,15,20-tetraphenyl-21H,23H-porphinetetrasulfonic acid (TPPS) is described. The copper(II)-TPPS complex was extracted on a membrane filter from an acidic solution containing Zephiramine (benzyldimethyltetradecylammonium chloride) and a large excess of perchlorate ion, leaving excess TPPS in the solution. The solid-phase absorbance of the copper(II)-TPPS complex on the membrane filter was measured at 417 nm. A linear calibration graph was obtained for up to 20 ng of copper(II) in a 20 ml sample volume; the limit of detection was 0.15 ng, based on three-times the standard deviation of the blank value. The proposed method was applied to the determination of copper in tap, river and sea water samples. The results are in fair agreement with those obtained by suspension-introduction graphite-furnace atomic absorption spectrometry using ammonium pyrrolidinedithiocarbamate and finely divided anion-exchange resin.