Exploitation of rhodamine-B as chromogenic reagent for the spectrophotometric determination of chromium (VI)

In the present study rhodamine-b dye has been used as a chromogenic reagent for the determination of trace amounts of chromium (vi). the spectrophotometric method developed is sensitive and can be used to determine nano gram quantities of chromium. rhodamine-b ion forms an association complex with chromium in acidic medium (orthophosphoric acid) in presence of potassium iodide and ascorbic acid. polyvinyl alcohol is used as solubilizing agent. rhodamine-bchromium complex shows absorption maxima at 600nm and all absorbance measurements are made at this wavelength. beer's law is followed up to 200 ng ml-1 of chromium in solution. the molar absorptivity for the chromium complex was found to be 2.3x105 l mol-1cm-1 at 600 nm. job's method indicates that the molar ratio of chromium to rhodamine-b is 1:3. studies on the stability of complex and optimum concentration of dye,ortho-phosphoric acid,ascorbic acid and potassium iodide were carried out. interference effects of several anions and cations were also studied.