Determination of Benzidine and 3,3'-Dichlorobenzidine in Wastewater by Liquid Chromatography with UV and Electrochemical Detection

Abstract

The title compounds art on the EPA priority pollutant list. Therefore, a sensitive method for their measurement it required. The liquid chromatographic method employs a LiChrosorb RP-2 column, 45% acetonitrile (pH 5) mobile phase, UV detection at 280 nm, and electrochemical detection at +0.70 volts applied potential. The three-electrode electrochemical cell described contains a tubular carbon-black/polyethylene working electrode that permits detection of sub-part-per-billion levels in a 50 μl injection. UV detection is about 50 times less sensitive, but a 500 μl injection permits detection of 2 ppb benzidine and dichlorobenzidine. Recoveries from fortified wastewater of benzidine at 1 to 6 ppb and dichlorobenzidine at 3 to 12 ppb levels were 83% and 87%, repectively.