Quantification of gentamicin in Mueller-Hinton agar by high-performance liquid chromatography

The aim of this study was to optimise a method for gentamicin determination in an agar matrix and to investigate if and how agar composition can affec t the gentamicin diffusion kinetics during the agar diffusion tests for ant ibiotics sensitivity. Gentamicin was separated by RP-HPLC and detected at 3 65 nm after pre-column derivatization with 1-fluoro-2,4-dinitrobenzene. Rec overy (greater than or equal to 79%), linearity (r(2)greater than or equal to0.997) and sensitivity (1 mug/ml) were assessed using four different agar matrices. The kinetics of gentamicin diffusion tested on BioMerieux and DI D manufacturers' products showed in uninoculated agar plates significant di fferences that were even more pronounced in the presence of Pseudomonas aer uginosa metabolism. (C) 2001 Elsevier Science B.V. All rights reserved.