Simultaneous Estimation of Ampicillin and Sulbactam in Human Plasma by Liquid Chromatography Tandem Mass Spectrometry

A LCMS/MS method for the simultaneous determination of ampicillin and sulbactam in human plasma was described. After protein precipitation using 2mL of acetonitrile, 250µL of supernatant was mixed with 1.000 mL of 0.1% Acetic Acid in Milli-Q-water. 10µL was injected to a Biobasic AX column and eluted with 10mM Ammonium acetate and Acetonitrile: 60:40, v/v at a flow rate of 0.5mL/min. MRM transitions were monitored in negative mode as m/z 348.1 → 206.8 (AMP), 231.9 → 187.8 (SUL) and m/z 353.0 → 211.9 (AMP D5). Sample concentrations were calculated by linear regression analysis using the analyst software1.6.3. An excellent linear response was obtained over the concentration ranges 0.1040µg/mL to 10.1562µg/mL for Ampicillin and 0.0510µg/mL to 6.1552µg/mL for Sulbactam. The intra-day and inter-day precision were within 3.50% for all analytes. The assay accuracy was 96.27 –103.59 %. Mean recoveries were 84.51% and 98.54% for ampicillin and sulbactam, respectively. The limits of detections were 0.026µg/mL and 0.013µg/mL for ampicillin and sulbactam. This method was successfully used for a bioequivalence study.