ANALYSIS OF GENTAMICIN SULFATE BY HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY COMBINED WITH THERMOSPRAY MASS-SPECTROMETRY

The quantitative analysis of gentamicin sulfate by high-performance liquid chromatography (HPLC) with mass spectrometry was performed on-line utilizing thermospray mass spectrometry (TSP-MS). Chromatographic reversed-phase separation utilizing trifluoroacetic acid as an ion pair reagent resulted in the observation by TSP-MS of the major components (C1a, C2 and C1) of gentamicin sulfate as well as an additional minor component. This minor component had the identical [M + H]+ ion and fragmentation pattern of the major fraction C2 which indicated that the minor component may be the C2a component. Method development and optimization of the mobile phase for HPLC-TSP-MS were accomplished with a variable simplex algorithm. HPLC with electrochemical detection was utilized in conjunction with the simplex algorithm to establish a mobile phase suitable for the HPLC-TSP-MS analysis of gentamicin sulfate. Bulk preparations of gentamicin sulfate were assayed by HPLC-TSP-MS for the major components by comparison with an external standard, and by a comparison of peak areas obtained for the individual components vs. the totaled peak areas.