A critical study of Brilliant green as a spectrophotometric reagent: the determination of perchlorate particularly in potassium chlorate

Abstract

A modified procedure for the extraction of perchlorate with Brilliant green into benzene is described, which gives a reproducible and nearly quantitative recovery of perchlorate (apparent ε_640nm= 94 000) and low blanks (A= 0·02 to 0·04). Studies on the use of untreated glassware, silanised glassware and polypropylene-ware have indicated that adsorption effects are not very important. Nevertheless, the standard and sample solutions should be treated in the same vessels and the absorbance measurements made in quartz cells. Brilliant green perchlorate can be extracted from aqueous solutions in the pH range 3 to 6·5, but the solutions should be buffered at a constant pH value. The procedure has been applied successfully to the determination of perchlorate in samples of potassium chlorate.