A sensitive and selective kinetic method is proposed for the determination of nanogram amounts of copper. The
method is based on the catalytic effect of copper on the reduction of Ponceau S by sodium sulfide in an alkaline
media. The rate of the reaction is monitored spectrophotometrically at 560 nm. The method allows determination of
copper concentrations in the range 2–400 ng ml1 with a relative standard deviation of 2%. The proposed method,
which is highly selective to copper, has been applied satisfactory to its determination in real samples. © 2001 Elsevier
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