1995 Volume 11 Issue 4 Pages 587-590
A laser-induced fluorescence detection system for capillary electrophoresis using a visible semiconductor laser and an avalanche photodiode has been developed. These solid-state devices offer both reliability and compactness for instrumental design. A time-resolved photon-counting method with a subnanosecond resolution has reduced the large dark counts of the avalanche photodiode and the contribution from scattered light. The baseline fluctuation of the electropherogram is due to the shot noise of the avalanche photodiode. The detection limit (S/N=2) for a model dye compound, Oxazine 725, is 2.1fmol as an injection amount. This value is comparable to that of the conventional laser fluorometry system with a gas laser and a photomultiplier.
