A new colorimetric estimation of cobalt is described. The procedure involves conver­ting the cobalt containing sample into COO2 and dissolving it in acetone and measuring the absor­bance at 680 nm. Common cations which otherwise give blue-green solutions do not interfere. The re­covery in all cases is better than 98% and the extinction co-efficient is large enough (560 M"I em-I) to allow submillimolar concentrations in a one em cell.


S A KAZMI ,M I KHAN ,