| Abstract: | High performance liquid chromatography coupled with electrochemical detection (HPLC-EC) method has been developed for the determination of benzidine and its related congeners in wastewater at the low ng/mL level. With a µ-Bondapak C18 column, 53% acetonitrile (pH 4.7), and electrochemical detection at +1.0 V applied potential, the detection limits range from 3 ng/mL for benzidine to 10 ng/mL for 3,3′-dichlorobenzidine, assuming a 100 µL injection. The detection limits can be further lowered to the sub-ng/mL level by incorporating a short precolumn into the HPLC system for on-line sample enrichment. Recoveries are generally greater than 80% — except for benzidine and 3,3′-diaminobenzidine which give 50–70% recoveries. Industrial wastewater samples from a coke-plant and a plant producing 3,3′-dichlorobenzidine based dyes were successfully studied via this method. |
