Improvements in detection sensitivity for the determination of ivermectin in plasma using chromatographic techniques and laser-induced fluorescence detection with automated derivatization.

Improvement in detection sensitivity for the analysis of ivermectin was observed through utilization of laser-induced fluorescence detection and by manipulation of chromatographic conditions. Gradient elution used in combination with narrow-bore chromatography and conventional fluorescence detection resulted in a limit of quantitation for the major homologue of ivermectin of 0.01 ng/ml in dog plasma. Laser-induced fluorescence detection with isocratic chromatographic conditions also resulted in a limit of quantitation of 0.01 ng/ml in dog plasma, which is a six-fold improvement over previously reported methods. Introduction of an automated procedure for the derivatization and injection of samples reduced the amount of sample handling, eliminated the potential for analyte/internal standard degradation and contributed to the overall ease of analysis.