Steroid analysis in single cells by capillary electrophoresis with collinear laser-induced fluorescence detection.

Capillary electrophoresis with collinear laser-induced fluorescence detection was used for the analysis of steroids in single R2C cells. Progesterone secretion was monitored from cultured cells and subsequently detected in single cells. Mass detection limit of 10(-18) mol for dansylated steroids was achieved with the 325-nm line of a helium-cadmium laser. Dansylhydrazine proved to be an effective fluorescent tag for derivatization of steroids outside and inside the biological cell. Fluorescence microscopy indicates that a dimethyl sulfoxide-containing physiological buffer was sufficient to incorporate the tag inside the cell for subsequent steroid derivatization.