Estimation of Cr(III) in Water with the Presence of Cr(VI) by Chlorophosphonazo I Color Reaction Spectrophotometry.

A method capable of accurately and selectively measuring Cr3+ in water is required and was therefore studied. The precision and reproducibility of chlorophosphonazo I color reaction spectrophotometry (CCRS) for the selective determination of Cr3+ was improved to be acceptable standards. The CCRS established is therefore an accurate, reproducible and inexpensive method. It also has reasonably good sensitivity and selectivity, and a high sample output. This method should be readily adapted for the routine and selective determination of Cr3+ in bottled mineral drinking water with (or without) the supplementation of Cr3+ or in natural water such as mineral or pipe water with the presence of Cr6+.