Analytical Method Development and Validation of N ‐Nitrosodibenzylamine in Lacosamide Drug Using LC–MS/MS Method: Quantification and Greenness Assessment

ABSTRACT N ‐nitrosodibenzylamine (NDBzA), a potential nitrosamine impurity, is usually formed during the synthesis of lacosamide active pharmaceutical ingredient (API) at low concentrations. The present work focuses on the development of a sensitive and robust analytical method employing multiple reaction monitoring (MRM) for the quantitative determination of NDBzA in the lacosamide API. A Zorbax SB‐Phenyl column (250 × 4.6 mm 2 , 5 µm) under gradient elution conditions was used for the separation of lacosamide and NDBzA. Overall, 0.1% formic acid in water was used as mobile phase‐A and 100% methanol was used as mobile phase‐B, with a flow rate maintained at 0.8 mL/min with gradient program. The gradient elution process consists of these steps: (Time in minutes/% mobile phase‐B) 0.01/40, 3.0/40, 10.0/90, 15.0/90, 15.1/40, and 21.0/40. An MRM approach was utilized for the quantification of NDBzA with a precursor‐to‐product ion transition of m / z 227 → 91.2 at a collision energy of −10.0 eV. From the quantification method developed here, the limit of detection (LOD) and limit of quantification (LOQ) for the NDBzA impurity were found to be 0.034 and 0.113 ppb, respectively. Further, accuracy results were within the acceptable range (70%–130%). The developed liquid chromatography coupled with mass spectrometry (LC–MS/MS) method is validated for good linearity, precision, accuracy, and suitability for the quantification of NDBzA in the lacosamide API. Furthermore, the environmental impact of the developed method was systematically evaluated using several greenness assessment tools, including AGREE (Analytical Greenness), NEMI (National Environmental Methods Index), MoGAPI (Modified Green Analytical Procedure Index), and the Analytical Eco‐Scale. The method achieved scores of 0.62 (AGREE), 76 (MoGAPI), and 83 (Eco‐Scale), indicating that it is environmentally friendly. The sustainability and environmental performance were quantitatively assessed using these standardized tools, confirming the improved eco‐efficiency of the method.