Method validation of residual cyanide determination in lamotrigine API using sensitive spectrophotometric method

Lamotrigine is known as an anticonvulsant or antiepilectic drug. Trace level of cyanide may remain in the product in cyanation step during manufacturing process. Based on the principle of sensitive colorimetric procedure, converting the product to cyanogen chloride, CNCl by reaction with chloramine-T and subsequently the formation of colored complex Quinquevalent Cyanide with pyridine-barbituric acid reagent, the residual cyanide content was determined. The method was validated for various parameters such as System suitability, Linearity, Method Precision, Accuracy and Intermediate precision by employing UV-Spectrophotometer. A wide linear range concentration of 0.015-0.1 mg/Kg was observed with r2 values ≥ 0.99. The sample was spiked at concentration level of 0.025; 0.05; 0.075 and 0.1 mg/Kg respectively and better recoveries between 80-120% with the acceptable relative standard deviation (RSD) i.e.