This investigation has demonstrated that the poly(dithiocarbamate) resin is usable for the differential determination of Cr(VI)-Cr(III) mixtures. In this example, a concentration factor of 12.5 was obtained. However, on the basis of previous experience with the poly(dithiocarbamate) resin both large sample volumes and smaller final solution volumes can be employed in order to increase the concentration factor. The present technique is suitable for chromium determination by inductively coupled plasma-atomic emission spectrometry (ICP-AES), atomic absorption spectrometry (AAS), and other spectrochemical methods. However, the low limit of detection for chromium achieved by electrothermal atomization AAS combined with a suitable small final digested resin solution volume may allow extension of the differential analysis to low initial Cr(VI) and Cr(III) concentration-levels. Although high chloride concentration does not interfere with the Cr(VI) determination in this technique, in the total chromium procedure a chloride concentration of greater than 250 mg of Cl/L prevents complete recovery of chromium possibly through the loss of chromyl chloride. In this situation, removal of chloride by precipitation with silver nitrate may be required. This limitation is not unique to the resin approach and is common in methods requiring oxidation of Cr(III) to Cr(IV). The present technique is not affected by largemore » concentrations of alkali and alkaline earth elements or manganese because these elements do not complex with the resin. In addition, the technique is simple and provides acceptable precision.« less