Determination of cadmium(II) with 5-Br-PADAP in the presence of CPC and HDPBA

Abstract

2-(5-Bromo-2-pyridylazo)-5-diethylaminophenol (5- Br-PADAP), a trihydroxy phenyl dye and <i>N</i>-hydroxy-<i>N,N '</i> diphenylbenzomidine (HDPBA), a reported extractant, in presence of a cationic surfactant (CPC) have been used for the spectrophotometric determination of cadmium(II). The Cd(II)CPC-(5-Br-PADAP) red coloured complex formed in aqueous medium has been extracted with <i>N</i>-hydroxy-<i>N,N '</i> diphenylbenzomidine in dichloromethane in the <i>p</i>H range 8.6-10.6. This extracted complex shows maximum absorbance at λ_max= 560 nm against reagent blank with molar absorptivity of 9.5×10⁴ dm³ mol^-1 cm^-1. The detection limit of the method is 0.01μg ml^-1. The relative standard deviation (RSD, n= 10) for solutions containing 0.40 μg ml^-1Cd(II) is 1.6%<i>. </i>The system obeys Beer's law in the range 0.05-1.0μg ml^-l. The effect of foreign ions and other experimental variables have been studied. Cd(II) has been successfully determined in standard, environmental and biological samples using the present method.