Simultaneous Second Derivative Spectrophotometric Determination of Gold and Cobalt

摘要

A simple, sensitive, and selective second order derivative spectrophotometric method has been developed for the simultaneous determination of gold(III) and cobalt(II) using 2-hydroxy-3-methoxy benzaldehyde thiosemicarbazone (HMBATSC) as a chromophoric reagent. The reagent (HMBATSC) reacts with Au(III) and Co(II) at pH 6.0, forming soluble blue and brown species, respectively. The second order derivative spectrum of [Au(III)-HMBATSC] exhibits reasonably sufficient amplitude at 435 nm and zero amplitude at 455 nm, and [Co(II)-HMBATSC] shows maximum amplitude at 455 nm and zero amplitude at 435 nm. This difference in amplitudes was utilized to develop a second order derivative spectrophotometric method for the simultaneous determination of Au(III) and Co(II) in a mixture without solving the simultaneous equations by measuring the second derivative amplitudes at 435 nm and 455 nm, respectively. Further, the Beer-s law was obeyed in the range 0.1178-3.7712 ml-1 of Au(III) and 0.1225-3.7400 -g ml~(-1) of Co(II). A large number of foreign ions do not interfere in the present method. The method is applied to the simultaneous determination of Au(III) in Rheumartho gold and Co(II) in Vitamin B_(12)samples.