HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHIC ANALYSIS OF AMINOGLYCOSIDE ANTIBIOTICS

A simple precolumn derivatisation method for the determination of amin oglycoside antibiotics (AGs) is described. The stability of the o-phth alaldehyde (OPA) derivatives of the AGs obtained using beta-mercaptopr opionic acid (beta-MP) was investigated by reversed-phase HPLC. One of the fluorescent derivatives of sisomicin was stable at least for 6 h in 50% methanol under the optimal conditions used (OPA concentration, pH and temperature). When plasma samples spiked with sisomicin were an alysed, the response was linear in the calibration range of 136-900 mu g of sisomicin per injected volume (40 mu l) As little as 0.06 mu g o f sisomicin per 1 ml of plasma could be detected with a signal-to-nois e ratio greater than or equal to 2. The method was also applied to who le blood samples from rabbit after a subcutaneous injection of 1 mg/kg of the AGs, using dried blood spots (DBS) on filter-paper punched dis cs. The detection limits of sisomicin and netilmicin in the DBSs on pu nched discs (10.1 mu l of whole blood) were 0.053 and 0.50 mu g per mi of whole blood, respectively (signal-to-noise ratio greater than or e qual to 2). The method permits a simple collection of blood at the mic rolitre level and should prove particularly useful for monitoring the AGs in blood at therapeutic levels in geriatric and paediatric patient s and could be also used for the preclinical study of the AGs blood le vels of a number of mice or rats without killing. An RP-HPLC method us ing an on-line clean-up procedure for large sample-volume analysis of serum AGs is also described. (C) 1998 Elsevier Science B.V. All rights reserved.