For automated determination of theophylline and valproic acid by use of Ames' fluoroimmunoassays we used a high-pressure liquid-chromatographic system consisting of a pump, a robotic unit (Gilson 231/401, to prepare and inject the samples into the flowing carrier), and a fluorometer with a 10-microL flow cell. Results correlated well with those of conventional liquid- and gas-chromatography (r less than 0.96). The between-run CV is about 5%. In comparison with the manual method, the volume of reagents (and thus the cost per analysis) was decreased by eightfold.