Utilization of activating and masking effects by ligands for highly selective catalytic spectrophotometric determination of copper and iron in natural waters.
A kinetic-catalytic spectrophotometric method is proposed for the successive determination of nanogram levels of copper and iron, which is based on their catalytic effects on the oxidative coupling of p-anisidine with N,N-dimethylaniline (DMA) to form a colored compound (lambda(max)=740 nm) in the presence of hydrogen peroxide at pH 3.2. 2,9-Dimethyl-1,10-phenanthroline (neocuproine) acted as an activator for the copper catalysis, and 1,10-phenanthroline (phen) acted as an activator for the iron catalysis. The selectivity was improved in the presence of diphosphate as a masking agent. The determinable ranges were 0.16-10 ppb for copper and 1-100 ppb for iron, respectively. The relative standard deviations of copper and iron were 1.1 and 0.97% for five determinations of 10 ppb copper and 40 ppb iron. The method was successfully applied to the analyses of copper and iron in tap, well, river and pond waters.
Ohno
Shinsuke
S
Department of Applied Chemistry, Aichi Institute of Technology, Yachigusa, Yakusa-cho, Toyota, Aichi, Japan.
Teshima
Norio
N
Zhang
Heng
H
Sakai
Tadao
T