An automated high-performance liquid chromatographic method for the determination of aminoglycosides in serum using pre-column sample clean-up and derivatization.

An automated high-performance liquid chromatographic method for the determination of the aminoglycosides amikacin, dibekacin, gentamicin, netilmicin, sisomicin and tobramycin is described. The procedure involves sample clean-up by adsorption of the aminoglycosides on a pre-column, subsequent derivatization with o-phthalaldehyde and on-line separation of derivatives by column switching. A short cation-exchange column serving concurrently as a guard column in combination with a reversed-phase column was used for separation. Except for the determination of netilmicin an internal standard consisting of an aminoglycoside was used in each assay. The signals of the aminoglycosides determined were linear within the range of 1-16 mg/l serum. The inter-assay imprecision (n = 10) calculated as coefficient of variation was less than 6%. The results were obtained within 20 min after injection of the serum sample. Easy performance and flexibility make the procedure feasible for therapeutic drug monitoring.