Spectrophotometric determination of microgram amounts of chromium(VI) and total chromium in waste water

The spectrophotometric determination of chromium(VI) in electroplating waste waters and total chromium(III, VI) in industrial waste waters using 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP) is described. This was found to be the most sensitive reagent for chromium. Comparisons with determination by the diphenylcarbazide methods and other reagents are shown in tables. The complex formed was very stable . A list of foreign ions is given, showing those which interfere and those which do not interfere with the determination.