DETERMINATION OF ULTRATRACE AMOUNTS OF COPPER(II) BY ITS CATALYTIC EFFECT ON THE OXIDATIVE COUPLING REACTION OF 3-METHYL-2-BENZOTHIAZOLINONE HYDRAZONE WITH L-N-(2-HYDROXY-3-SULFOPROPYL)-3,5-DIMETHOXYANILINE

A spectrophotometric method was developed for the determination of ult ratrace amounts of copper(II) based on its catalytic effect on the oxi dative coupling reaction of 3-methyl-2-benzothiazolinone hydrazone wit h l-N-(2-hydroxy-3-sulfopropyl)-3,5-dimethoxyaniline to produce an int ensely coloured dye (lambda(max)=525 nm) in the presence of hydrogen p eroxide, In this reaction, pyridine acted as an effective activator fo r the catalysis of copper(II). By measuring the absorbance of the dye, copper(II) can be determined at the 0.002-0.1 ng cm(-3) (3.1x10(-11)- 1.6x10(-9) mol dm(-3)) level. The relative standard deviation for ten determinations of 0.06 ng cm(-3) of copper(II) was 2.6%. The proposed method was successfully applied to the determination of copper(II) in tap water and biological material.