The immunoassay of methotrexate by capillary electrophoresis with laser-induced fluorescence detection.

Immunoassay is widely employed as a highly sensitive, specific analytical method for hormones and drugs in biological samples. A technique utilizing capillary electrophoresis with laser-induced fluorescence detection was examined based on the reaction process of these immunoassays in order to develop a protocol characterized by high sensitivity and high speed. The conditions of the antigen-antibody reaction and capillary electrophoresis were variously examined using fluorescein-labeled methotrexate and the antibody of methotrexate. As a result, the immunoassay could be completed within a few minutes. Moreover, detection in the pg range could be accomplished. The sensitivity corresponded to that of radioimmunoassay. A simultaneous multi-component analysis of the immunoassay is also possible due to the high resolving power of capillary electrophoresis. In this study, the possibility of a simultaneous analysis of methotrexate and vancomycin was also investigated.