Overlapping-peak resolution and quantification using derivative spectrophotometry in capillary electrophoresis

Derivative spectrophotometry is introduced for the quantification of overlapping peaks in capillary electrophoresis. The application for resolving overlapping peaks is tested using eleven benzoic acids as examples. Compared with common spectrophotometric detection, the derivative mode has slightly lower reproducibility, comparable sensitivity but much higher separation efficiency as the peak is much sharpened. Derivative spectrophotometry offers the advantages of reagent-, time- and labor-saving since only few optimizations of separation conditions for normal CE are essential to make the peaks partly baseline-resolved. Analysis of real samples using the method was also performed and results obtained give evidence of the potential for improved quantification without loss in accuracy.