Rapid and sensitive determination of aminoglycoside antibiotics in water samples using a strong cation-exchange...

A simple and sensitive chemiluminescence (CL) detection approach was developed for the direct analysis of aminoglycoside antibiotics in water samples following strong cation-exchange chromatographic (SCX-HPLC) separation. This detection system, which eliminates the need for sample derivatisation, is based on the inhibitory effect of aminoglycosides on the CL reaction between luminol and hydrogen peroxide catalysed by copper(II). As the operational and chemical variables that affect the CL signal were optimised, ionic strength and the Triton X-100 micelles turned out to be the keys to obtain maximum CL efficiency. Aminoglycosides were successfully separated in 10 min on a SCX column using a mobile phase consisting of an aqueous solution containing 5.0 x 10(-3)mol/l sodium acetate and 0.65 mol/l sodium chloride at pH 6.1. Sample volumes of 50 ml were preconcentrated by passage through a weakly acidic IRC-50 exchange column. Limits of detection from 0.7 to 10 microg/l and relative standard deviations from 2.7 to 5.4% were thus obtained. The proposed method surpasses other chromatographic alternatives in terms of the limit of detection, sample requirements for analysis and cost.