Spectrophotometric determination of trace cobalt(II) with thin layer resin phase based on a ternary complex system

A new method for the determination of cobalt in water sample with thin layer resin phase spectrophotometry was established. In acid medium,a ternary association complex system which was formed by SCN-,Co(Ⅱ) and strong alkalescence anion exchange resin had the maximum absorption at the wavelength of 630 nm. Due to the increasement of absorbance sectional surface and the π electron free space of the complex in the resin phase,the sensitivity was 20 times larger than that in water solution. The apparent molar absorptivity e630 was 2.1×105 L·mol-1·cm-1. The RSD of the method was 3.1%(n=6) for determination of 10.0 μg cobalt in 25 mL solution. Beer's law is obeyed in the range of 0-640 μg/L with detection limit of 8.8 μg/L. As compared with AAS,the results for determination of cobalt content in actual water samples were satisfactory.