Development of an UPLC‐MS/MS approach to detect and quantify N‐nitroso mirabegron in mirabegron

In the mirabegron (MIR) synthesis, the N‐nitroso mirabegron (NNM) is obtained during synthetic process of MIR; water is being used in reaction under acidic condition. Nitrite source is from water, and secondary amine source is from MIR as it has secondary amine; NNM is generated as an impurity during the synthesis of MIR. The presence of NNM in MIR could potentially affect its effectiveness. The purpose of this study was to establish a Ultra‐performance liquid chromatography‐mass spectrometry/mass spectrometry (UPLC‐MS/MS) methodology to identify NNM in MIR samples. The method for NNM analysis was developed on Acquity HSS T3 (100*2.1) mm 1.8 μm column with gradient elution using mobile phase consisted of 0.1% formic acid in water (mobile phase A) and 0.1% formic acid in methanol (mobile phase B). Mass spectrometer with electrospray ionization operated in the MRM mode was used in the analysis of NNM (m/ z 426.20 → 170.00). The UPLC‐MS/MS methodology proposed showed a good linearity (0.02 to 0.72 ppm), good system precision (RSD = 0.57%), good method precision (RSD = 0.87%), acceptable accuracy (94.5–116.5%), low detection limit (0.006 ppm) and low quantification limit (0.02 ppm) for NNM. The UPLC‐MS/MS methodology proposed can be utilized to assess the quality of MIR sample for the presence of NNM impurity.