Development and validation of a RP-HPLC method for the estimation of netilmicin sulfate and its related substances using charged aerosol detection.

Netilmicin is a semi-synthetic aminoglycoside antibiotic used against a broad spectrum of Gram-negative bacteria. A reversed-phase high-performance liquid chromatographic method has been developed to determine the composition of netilmicin sulfate and to estimate its related substances without pre- or post-column derivatization. A UV detector cannot be used to detect low levels of known and unknown related substances of netilmicin, as it has only a weak UV chromophore. A charged aerosol detector was used instead to obtain the high sensitivity that was necessary for the intended purpose of the method. This method can separate all related substances of netilmicin. A (10 cm x 4.6 mm) pentafluorophenyl high-performance liquid chromatographic column from Restek was used with a mobile phase consisting of (A) pentafluoropropionic acid-water-acetonitrile (0.1:96:4, v/v/v) and (B) trifluoroacetic acid-water-acetonitrile (1:96:4, v/v/v).