DEVELOPMENT AND VALIDATION OF AN ENVIRONMENTALLY SUSTAINABLE LIQUID CHROMATOGRAPHY METHOD FOR QUANTIFICATION OF LOXAPINE AND CHARACTERIZATION OF ITS DEGRADATION PRODUCTS BY LCMS/MS

The green analytical UPLC methods are highly effective for quantifying impurities because these methods reduce the usage of harmful chemicals and generate less waste leading to minimal environmental influence. Currently, there are no green methods reported for quantifying impurities in Loxapine and hence this study plans to fill the gap noticed in the literature. In method optimization, various compositions of green solvents including ethanol, and water with buffers were utilized as mobile phase. The conditions that produce acceptable results were studied for valuation in terms of linearity, accuracy, precision, and sensitivity. This method was applied for the resolution and structural evaluation of degradation products (DPs) of Loxapine using LCMS/MS. The method comprises Waters Acquity UPLC® HSS C18 (2.1mm × 100mm, 1.8µm) column along with ethanol, 0.1M Formic acid in water, and water in 50:20:30 (v/v) at pH 4.8 at 0.75 mL/min flow and 265 nm. All validation parameters were tested, and acceptable results were obtained for Loxapine and its impurities. The stress study identified three separate degradation products in the acid and base degradation chromatograms, labeled DP 1, DP 2, and DP 3. MSn studies and mass fragmentation analysis confirmed DP 1 as 2-chlorodibenzo[b,f][1,4]oxazepin-11(10H)-imine, DP 2 as 3-chloro-N-phenylbenzene carboximidamide and DP 3 as N-(2-chlorodibenzo [b,f][1,4]oxazepin-11-yl) -N-methylethane-1,2-diamine. The Greenness of the method was evaluated using GAPI (Green Analytical Procedure Index) and AGREE (Analytical GREEnness) tools, confirming that this technique can greatly cut down the use of harmful solvents while maintaining good chromatographic results. Hence, this method is effective for evaluating impurities of Loxapine and also characterizing its DPs.