RESUMO
OBJECTIVE: To establish a method to determine the genotoxic impurity, N-nitroso-N-methyl-4-aminobytyric acid, in losartan potassium using high performance liquid chromatography triple quadrupole mass spectrometry (HPLC-MS/MS). METHODS: The method was developed by using Shimadzu Shim-pack XR-ODS II column (2.0 mm×150 mm, 2.2 μm). Time program was conducted with mobile phase consisting of water (0.1% formic acid, A) and methanol (B). The flow rate was 0.3 mL•min-1, and the column oven temperature was maintained at 40 ℃. The samples were ionized by electrospray ionization (ESI) with multi reaction monitoring (MRM) data acquisition mode. The collision energies were -11, -13, and -13 V, CID gas was argon with pressure of 270 kPa.3 pairs of precursor, and product ions (m/z) of NMBA were 147.15→117.10, 147.15→87.10, and 147.15→44.10, respectively. RESULTS: The genotoxic impurity NMBA showed linearity between 1 and 100 ng•mL-1 with correlation coefficient of 0.999 9. The intra-day and inter-day repeatability was examined by relative standard deviations (RSDs) of retention time and peak area (RSD<1.10%, n=6 for intra-day repeatability and n=18 for inter-day repeatability). The accuracy was examined by percent recovery at three concentration levels, and the average percent recovery was between 94.40% and 98.04%. CONCLUSION: The established LC-MS/MS method is efficient for limit test and quantitation of NMBA in losartan potassium bulk drug.