Primary-Secondary Wavelengths Spectrophotometric Determination of Trace Amounts of Cadmium with 2,4-Dibromo-6-Carboxy-Benzenediazoaminoazobenzene

Abstract

In basic solution and in the- presence of non-ionic surfactant,
emulsifier OP, the reaction of cadmium (Cd²⁺) with new chromogenic
agent, 2,4-dibromo-6-carboxy-benzenediazoaminoazobenzene
(DBCBAA) forms red complex. It is one of most sensitive
determinations of trace cadmium in environment. Because of the
interference of excess of DBCBAA on complex absorbance the new
method, primary-secondary wavelengths spectrophotometry
(PSWS), was applied for the determination of trace amounts of
cadmium in wastewater. The results showed that the working wavelengths
should be selected at 520 and 610 nm and such a method
gives out the higher precision, accuracy and lower detection limit
than by ordinary spectrophotometry. By testing several wastewater
samples, the relative standard deviations were less than 7.2% and
the recovery rate of Cd is between 90 and 108%.