Comparative study of electrospray mass spectrometry and first derivative method and validation by HPLC method

Three different methods are described for the simultaneous determination of amoxicillin trihydrate (AMX) and potassium klavulanate (KLV) in synthetic mixtures and pharmaceutical tablets. The first method depends on the first-derivative ultraviolet spectrophotometry with zero-crossing measurement. The second method is based on mass spectrometry utilizing electropspray ionization. For the electrospray studies in negative and positive ion modes, aspirin (ASP) and clindamycin (CLN) were used, respectively as internal standards for quantification. The calibration function was established in the same concentration ranges as in the first derivative method. A reversed-phase high performance liquid chromatographic (RP-HPLC) method involving ultraviolet detection (γ = 220 nm) was developed for the analysis of AMX and KLV. Chromatography was carried out on a C-18 column with mobile phase comprising of phosphate buffer-acetonitrile (40:60, v/v). The proposed methods have been validated with regard to the selectivity, detection limit, recovery, accuracy and precision. For both drugs, methods were found to be selective, linear (R ≈ 0.99), accurate (recovery = 100-105%) and precise (<3% RSD) in the range of 21-49 μg/mL for AMX and 3-7 μg/mL for KLV. The limit-of-detection and limit-of-quantification of the method were determined for three methods.