Determination of Gentamicin Sulphate in Injection Solutions by Derivative Spectrophotometry

Abstract

A new derivative spectrophotometric method was developed for determination of gentamicin beside methyl and propyl hydroxybenzoates in injection solutions. The determination was carried out after modifying the gentamicin molecule by reaction with o-phthal aldehyde. The obtained spectrum of product in methanol solution was converted into a third-derivative spectrum. The measurements were made at wavelength λ = 281 nm, where a linear relationship between D3 and antibiotic concentration occurs, when no coexisting constituents are present. The method is of high specificity to gentamicin in the presence of methyl and propyl hydroxybenzoates and has good accuracy. The recovery is from 99.38% to 100.16%, and wide linearity ranges from 0.004% to 0.008%. The method has satisfactory precision (RSD = 2.52%) as well as high sensitivity (LOD = 1.66 · 10⁻⁴% and LOQ = 5.04 · 10⁻⁴%).

Keywords:

• Drug analysis
• gentamicin
• spectrophotometric determination