Development of β-Correction Spectrophotometric Principle and Analysis to Chelates Characteristics

Abstract

A new analytical principle, named β-correction spectrophoto-metric

principle, has been developed for the determination of trace amounts of

metal and the analysis of its chelates' characteristic parameters. It is first

to eliminate completely the interference of the excess of a ligand from its

coloured solution with a metal to give out the real absorbance of the formed

chelate. The reactions of gold(III) and silver(I) with p-dimethylaminobenzal

rhodanine (PDR) have been used for the determination of their

chelates' composition ratio (γ) and practical molar absorptivity (ε_P) and

the determination of trace amounts of copper has been made with the

calculation of the above characteristic parameters, using the new reaction

of copper and the ligand, o-bromobenzenediazoaminobenzene-p-azobenzene

(OBDA) at pH 12. Results showed that the chelates formed are

AU₂(PDR), Ag(PDR) and Cu(OBDA)₂, their respective ε_p to 2.79 X 10⁹,

1.31 x 10⁴ both at 550 nm and 9.41 x 10⁴ L mol^–1 cm^–1 at 500 nm. The

determination for the analysis to practical samples showed that the relative

standard deviations were less than 3.1 % and the recovery of copper is

between 91 and 106%.