A novel and sensitive spectrophotometric method for the determination of co
pper in the presence of high concentrations of interfering ions was studied
. The new method, based on the complex formed between copper and 4,5-dimerc
apto-1,3-dithyol-2-tionate, was applied to the determination of copper in m
etallic alloys used in dental amalgams with high amounts of tin and silver.
The lowest copper concentration detectable was 64 mu g L-1 and the range o
f concentrations that fellow Beer's Law was 0.350 to 1.06 mu g mL(-1). The
average copper concentration found in metallic amalgams was 10.54% with a s
tandard deviation of +/-0.76% and recovery of 97.5%. The spectrophotometric
method using cuproin and atomic absorption spectrometry was employed for c
omparison purposes, and no significant differences were observed among the
methods. (C) 1999 Academic Press.