Cadmium yellow detection and quantification by voltammetry of immobilized microparticles

Cadmium pigments (cadmium sulfide and cadmium sulfoselenide) produce intense colorings such as yellow, orange and red, and are well-known pigments in artists' colors, plastics, glasses, ceramics and enamels. This makes cadmium yellow a widespread pigment and hence is very interesting to develop a simple and fast procedure for its identification. Here we propose a straightforward procedure that is harmless to the sample allowing its application to valuable samples and also to very small samples. Three different electrochemical procedures were developed for the identification and quantification of CdS. They are based on voltammetry of immobilized microparticles that suffer a reductive scan at 60 mVs(-1) from +0.30 V to -1.00 V producing peaks whose potential allows identification of the pigment. For quantitative purposes a pretreatment of -1.50 V for 10 s was applied and then an oxidative scan was performed. The relative position of the Cd oxidation peak to the peak potential of an internal standard (AgCl) was used to proceed to the calibration.