Capillary electrophoresis assay of netilmicin sulphate

An effective method based on capillary electrophoresis (CE) for the determination of netilmicin sulphate in commercial ophthalmic formulations was developed and validated. The use of a polymer-coated capillary and a non-absorbing running buffer permitted the elution of netilmicin in cationic mode at pH 3.0 and with direct UV detection at λ = 195 nm. Since pre-treatment of the samples is not required, this procedure may be straightforwardly applied to the other aminoglycosides provided that their extinction coefficient is not too low.