SELECTIVE ONLINE PRECONCENTRATION OF PROTEINS BY TANDEM METAL CHELATE-CAPILLARIES CAPILLARY-ZONE ELECTROPHORESIS

Fused-silica capillaries having surface bound iminodiacetic acid metal chelating functions were developed for the selective on-line preconce ntration of dilute protein samples prior to capillary zone electrophor esis. The metal chelate capillaries with immobilized zinc proved effec tive in the selective accumulation of detectable amounts of proteins f rom dilute samples. They permitted the detection of 25 times less conc entrated samples than by CZE alone with concentration sensitive detect ors. Large sample volumes could be introduced without affecting separa tion efficiency. Besides demonstrating the effectiveness of metal chel ate capillaries in the quantitative determination of proteins from dil ute samples, the effects of pH, composition of electrolytes and sample feeding time on the analytical signal were examined with carbonic anh ydrase, a zinc binding protein.