Development and validation of rapid ultra high performance liquid chromatography with tandem mass spectroscopic method for the quantification of N‐nitrosodimethyl amine and N‐nitrosodiethyl amine in sitagliptin and metformin hydrochloride immediate and extended‐release formulations

A simple, effective LC–MS based method is developed and validated to determine N‐nitrosodimethylamine and N‐nitrosodiethylamine in pharmaceutical formulations of Sitagliptin and Metformin hydrochloride combination dosage forms. Atlantis T3 (100 × 3 mm, 3 μm) column, eluent‐A (0.1% formic acid in water), and eluent‐B (0.1% formic acid in methanol) were used to achieve chromatographic separation. A gradient program time (min)/%B: 0.01/3, 2/3, 4/55, 5/55, 5.5/90, 6.0/90, 6.5/3, and 7/3, and column flow rate: 0.75 mL/min was employed. The column oven and auto sample cooler temperatures were 40°C and 10°C, respectively. Atmospheric Pressure Ionisation positive mode with corona discharge potential as 4.0 V, drying gas (N2) flow as 110 mL/min, and nebulizer gas (N2) flow as 350 mL/min. Employing PerkinElmer triple quadrupole mass spectrometer, QSight 200 series, the source temperature was 450°C, and hot surface‐induced desolvation temperature was 250°C. Under optimized conditions, diluent‐1 and diluent‐2 offered better recovery and improved peak shapes. The required method sensitivity of nitrosodimethylamine (LOQ 0.74 ng/mL) and nitrosodiethylamine (LOQ 0.37 ng/mL) for the nitrosamine impurities were achieved using an optimized test concentration of Metformin hydrochloride at 45.7 mg/mL.