A fast, validated UPLC method coupled with PDA-QDa detectors for impurity profiling in betamethasone acetate and betamethasone phosphate injectable suspension and isolation, identification, characterization of two thermal impurities.

For impurity profiling of betamethasone acetate and betamethasone phosphate injectable suspensions, a quick, verified stability indicating UPLC technique incorporating the detectors PDA-QDa had been established. This method with an analysis time of 12min could able to separate all possible degradation impurities. Two of the thermal impurities have been identified in positive mode of detection by using QDa detector and isolated by using preparative HPLC. The method works at a flow rate of 0.5mL/min in column: Poroshell 120 EC C18 (100×2.1)mm, 1.9µm, maintained temperature precisely at 40°C. The M/Z values in ESI positive mode for the two new degradation impurities have been identified (M+H) as 393.22 (DP1), 363.17 (DP2) and confirmed by 1H NMR. The approach was also verified in accordance with the rules of ICH Q2 (R1). From LOQ quantity value to 150% quantity of specified concentration (2% for betamethasone and 0.5% for other impurities), the technique of UPLC-PDA-QDa was proven to be linear and accurate. Precision and ruggedness results showed˂5% RSD. Accuracy results showed more than 95% recovery from LOQ till 150% of impurity specification. This UPLC-PDA-QDa methodology was found specific, precise, stable and robust for quantification of all possible degradation impurities. The proposed method has been transferred to quality control laboratories to access the impurity profile during product storage.