A sensitive, selective and rapid liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) method has been developed for the estimation of mesalamine in human plasma using a derivatization technique. A liquid-liquid extraction technique with ethyl acetate was used for the extraction of mesalamine and mesalamine-D3 internal standard (IS). Mesalamine and mesalamine-D3 were analyzed on Thermo BetaBasic C8 (100 mm ´4.6 mm, 5 mm) column using acetonitrile and 10 mM ammonium formate in 70 : 30 v/v ratio under isocratic elution mode. The MS detection and quantitation were performed under multiple reaction monitoring using positive ESI for mesalamine (m/z, 210.1 ® 191.9) and mesalamine D3 (m/z, 213.2 ® 195.1). Main advantages of the proposed method include higher sensitivity (5.00 ng/mL), superior extraction efficiency (³79%), and small volume (200 mL) of sample for processing. The calibration curve was linear in the concentration range of 5.00 -2957.17 ng/mL with a good correlation coefficient (r 2 ³ 0.9980) for mesalamine. The intra-batch (within day) and inter-batch (between days) precision (% CV) and accuracy (% nominal) values varied from 2.09 to 4.44% and from 96.02 to 103.23%, respectively. The method was validated as per the US FDA guidelines and the results were found accurate and precise.

Objective: To develop a simple, rapid, precise and reproducible liquid chromatographic method for the estimation meropenem (MEP) and vaborbactam (VAB) in bulk and pharmaceutical formulation and study of the stability of the drugs in different stressed conditions. Methods: The chromatographic separation was achieved on a Kromasil C18 column (250 × 4.6 mm) using a mobile phase composition of acetonitrile and 10 mmol phosphate buffer (pH 3.50) in a ratio 30:70 v/v, pumped at a flow rate of 1.0 ml/min with UV detection set at 260 nm. Results: Symmetrical and sharp peaks of MEP and VAB were obtained at retention times of 2.29 and 3.10 min, respectively. The chromatographic method was validated for linearity, limits of detection and quantitation, precision, accuracy, system suitability and robustness. Calibration curves were obtained in the concentration ranges of 25–150 μg/ml for MEP and VAB. Stability tests done through the exposure of the analytes solution for different stress conditions and the obtained results indicate no interference of degradants with HPLC method. Conclusion: The proposed method has been found to be selective, precise, linear, accurate, and sensitive. The method can be successfully applied to the assay determination of bulk drugs and combined dosage forms for routine analysis.

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