Development of a sensitive LC-MS/MS method for simultaneous determination of three nitrosamines in losartan API and assessment of nitrosamines formation

Nitrosamine impurities, even in trace amounts, are one group of the toxic substances have been proven to be carcinogenic and mutagenic for humans. The nitrosamine contaminants in pharmaceuticals have led to significant regulatory response and need to be controlled at or below compound-specific limits. In this study, we developed and validated a sensitive, selective, and high-throughput method based on liquid chromatography tandem mass spectrometer (LC-MS/MS) for the simultaneous determination of three nitrosamines in losartan potassium API. N-nitrosodiethylamine (NDEA, m/z 102), N-nitrosodiisopropylamine (NDIPA, m/z 130), and Nnitrosodibuthylamine (NDBA, m/z 159) levels were quantified using an APCI source on LC-MS/MS, under a multiple reaction monitoring (MRM) acquisition method. Good linearity with a determination coefficient (R-2) > 0.999 was achieved over the concentration range of 0.5-50 ng/mL. The limits of detection (LODs) and the limits of quantitation (LOQs) were respectively 0.42 and 1.27 ng/mL for NDBA, 1.7 and 3.2 ng/mL for NDIPA, 1.96 and 5.95 ng/mL for NDEA. The accuracy, in mean recovery %, were 102.33 % for NDBA, 102.51 % for NDIPA and 97.05 % for NDEA. The results from method precision (RSD %) were 3.90 %, 2.32 % and 2.58 % for NDBA, NDIPA and NDEA, respectively. Eight batches of commercial products containing losartan were analyzed, none of which showed presence of nitrosamines. After assessment of nitrosamines formation during stress conditions, the analytical method showed MRM transitions to NDEA after losartan subjected to UVA for 24 h. In conclusion, the developed method was successfully applied to identify and quantify nitrosamines in losartan API using LCAPCI-MS/MS.