A method for the estimation of traces of chlorhexidine in water

A simple method of estimating traces of chlorhexidine in water using bromothymol blue is described. The procedure involves the extraction of the chlorhexidine/bromothymol blue complex into carbon tetrachloride from a buffered neutral solution and measurement of the absorbances of the extracts in a spectrophotometer. The extracted complex has good colour stability, and the method is accurate, reproducible, and very sensitive, with concentrations of chlorhexidine down to 0.05 micrograms ml-1 measurable.