Determination of Nanogram Amounts of Copper(II) by the Catalytic-Photometric Method

Abstract

The effect of several buffers was examined for the catalysis of copper(II) in the reaction of N, N-dimethyl-p-phenylenediamine with N, N-dimethylaniline to form Bindschedler′s Green (λmax=725nm) in the presence of hydrogen peroxide. The buffer agents which were examined included imidazole, 2, 4, 6-trimethylpyridine (TMP), piperazine-N, N′-bis(2-ethanesulfonic acid) (PIPES), N, N-bis(2-hydroxyethyl)-2-aminoethanesulfonic acid (BES), 3-(N-morpholino)-propanesulfonic acid (MOPS), and N-2-hydroxyethylpiperazine-N′-2-ethanesulfonic acid (HEPES). Among them TMP was found to be the most favorable agent in this reaction system. The established catalytic method is given for the 0.05-1.0ng cm-3 range of copper(II), and has an effective sensitivity index of 1.1×10-3ng cm-2.