Two spectrophotometric methods are proposed for the assay of oxcarbazepine (OXC) in bulk and dosage forms using Folin-Ciocalteu phenol reagent (FCP) and 3-methyl-2-benzothiazolinone hydrazine hydrochloride (MBTH) as reagents. The first method involves addition of FCP reagent to OXC in alkaline medium followed by measurement of absorbance at 760 nm (method A), and the other involves addition of a fixed volume of MBTH after treatment of OXC with ferric chloride and measurement of absorbance at 456 nm (method B). In both methods, the amount of chromogen formed corresponds to the amount of OXC and the measured absorbance was found to increase linearly with the concentration of OXC, which is corroborated by the correlation coefficients of 0.9985 and 0.9984 for method A and B, respectively.
The systems obey Beer's law for 5--30 μg mL-1 and 10--50 μg mL-1 for methods A and B, respectively. The apparent molar absorptivity was calculated to be 8.06 x 103 L mol-1 cm-1 and 3.126 x 103 L mol-1 cm-1 for methods A and B, respectively. The limits of detection (