Determination of carbamazepine in uncoated and film-coated tablets by HPLC with UV detection

A simple and reliable method for the determination of carbamazepine in uncoated and film-coated tablets has been developed and validated by higb-performance liquid chromatography with ibuprofen as the internal standard. The tablets were weighed and ground individually, and were extracted in methanol using method of sonification. The extract was diluted and purified using 0.45 mum membrane filter. Separation was achieved on an Econosphere C 18 5mu analytical column with a mobile phase of 28:72 acetonitrile: sodium phosphate buffer. Detection was at UV 230 nm using a photodiode array detector. The mean retention times of carbamazepine and ibuprofen were 4.2 and 12.3 min, respectively. Peak height ratios were fit to a least squares linear regression for calculation of standard regression equation. The linear calibration range was from 5.0-25.0 mug/mL with the lower limit of detection (LLOD) of 18 ng/mL and the lower limit of quantitation (LLOQ) of 60 ng/mL. This simple and convenient method produced good linearity, precision, and accuracy and avoids using methylene chloride as the mobile phase. A modified USP method was also carried to analyze the drug content in the tablets. These results were compared statistically, and no difference was found between the new method and the modified USP method, while the new method is more convenient and is suitable for stability and dissolution studies of this drug.