Real-time detection of DNA during gel electrophoresis using a Zeeman refractive index detector.

We have developed a new method for detecting unstained, untagged, unlabeled DNA bands in real-time during gel electrophoresis. This technique is based on the use of a Zeeman refractive index detector with lambda/12,000 resolution and outstanding stability. Current sensitivity in a polyacrylamide gel is 0.2 ng of DNA in the probe beam. We believe this can be significantly improved. We don't understand why the DNA initially decreases, then dramatically increases, the local refractive index as it passes through the gel, although we propose three possible mechanisms.