A MINIATURIZED, HIGH COLLECTION EFFICIENCY CHEMILUMINESCENCE DETECTOR FOR CAPILLARY ZONE ELECTROPHORESIS

A miniaturized, high collection efficiency, post-column, sheath flow chemiluminescence (CL) detector for use with capillary zone electrophoresis (CZE) is described. The stainless steel detector body significantly cuts down the electrical noise associated with the AC power lines. The inner wall of this CL detector was carefully machined to a high smoothness to increase retro-reflection. The other advantage of this novel CL detector arises because the PMT is placed extremely close to the separation capillary to increase the solid angle for light collection. Calculations indicate that the collection efficiency of this chemiluminescence detector is ≈58%. The miniaturized CE-CL detector is characterized using transition metal cations as the sample species. The major problem for the separation of transition metal cations is their strong adsorption to the surface of the fused silica capillary. A theoretical plate number of 340,000 for 1.0 × 10 −11 M Co 2+ is demonstrated. Detection limits of 1.5 × 10 −12 M for Co 2+ , 5.0 × 10 −8 M for Cr 3+ , and 3.0 × 10 −8 M for Cu 2+ are reported.