Carbamazepine is top essential listed medicine under anticonvulsant, it is alone or with combination with others medication used to control seizures chronic or acute. It is mainly working by reducing abnormal electrical activity towards the brain. But the recent complaint this medicine is, it containing several number of impurities in different monograph books and as per the route of synthesis, different number of reactant impurities which is not listed in pharmacopoeias. The present work aim to develop novel separation condition for the simultaneous estimation of listed impurities as well as unknown impurities. The RP HPLC method was chosen to develop ideal separation. C₁₈packed (250 cm×4.6 cm, i.d. 5 µm particles) used as a stationary phase, acetonitrile and buffer (50mM ammonium formate) at the ratio of 60: 40 v/v was used as a mobile phase. The detection was achieved at 275nm. Drug substance and all the associated impurities well resolved each other and there was no interference obtained from the diluent. The developed method validated as per ICH Q2 (R1) guidelines. In addition four new impurities were separated. Those new impurities were structurally characterized as per LCMS data. To conclude, the developed method can successfully adopt for the simultaneous estimation of carcinogenic reactant based impurities.     This study provided approach knowledge to upgrade the list of impurities in the monograph books.

Index Terms- Carbamazepine, RP-HPLC, LC-MS, Acetonitrile, Impurities (bromobenzene, nitro toluene, iminostilbene, iminodibenzyl).