Primary-Secondary Wavelength Spectrophotometric Determination of Trace Amounts of Cadmium in Wastewater with New Chromogenic Agent m-Nitrobenzenediazoameno azobenzene

Abstract

In basic solution and in the presence of non-ionic surfactant
emulsifier OP, cadmium (Cd²⁺) reacts with new chromogenic agent,
m-nitrobenzenediazoaminoazobenzene (m-NBDA) to form yellow
complex. This paper describes the determination of trace amounts
of cadmium in wastewater by the updated method named primary-secondary
wavelengths spectrophotometry (PSWS). The results
showed that the working wavelengths should be selected at 460 and
550 nm and such a method gives higher precision, accuracy and
sensitivity than that of ordinary spectrophotometry. By testing
several wastewater samples, the relative standard deviations were
less than 9% and the recovery rate of Cd between 91.8 and 110%.