Continuous-flow fluoroimmunoassay of serum gentamicin, with automatic sample blank correction.

We describe the continuous-flow automation of a quenching fluoroimmunoassay for determination of the antibiotic gentamicin in serum. In the flow system, sample is mixed with fluorescein-labeled gentamicin, followed by antiserum, and after a short incubation the fluorescence is measured. The intrinsic blank signal of each sample is corrected for during its single passage through the system by pumping antiserum discontinuously, so as to divide the final stream into sections corresponding to conventional separate assay and blank mixtures. Analyses time for each sample is 6 min, and 20 samples can be run per hour. Sensitivity, precision, and accuracy are adequate for clinical purposes, and assays of patients' samples correlate satisfactorily with the results of manual quenching and polarization fluoroimmunoassays, and plate diffusion bioassay.