Resumen
Introduction: Niclosamide(NICS) its chemical name 5-chloro-N-(2-chloro-4-nitrophenyl)-2-hydroxybenz-amide]is the only commercially existing molluscicide optional by the WHO for large extent use in schistosomiasis be in charge of programs . NICS and its two new synthesized derivatives constructed to float on the water surface were able to kill cercariae, also obsessed promising activity in vitro nearby to an apicomplexan parasite Toxoplasma (4). Few spectrophotometric methods have been reported for the estimation of NICS as pure and in formulations, approximately these methods depend on reduction of nitro group (almost with zinc powder in acidic medium) followed by reaction with different reagents. The method based on reduction of nitro group of NICS then reaction of reduced-NICS with para- N,N-dimethylaminobenzaldehyde in non-aqueous medium (methanol) to form a colored product that has been proved successfully for the estimation of NICS in pharmaceutical and veterinary formulations Material and method :All reagents used are of analytical grade and are obtained from Fluka or Aldrich , NICS was supplied from SIGMA companies. Methanolic solution of para- N,N- dimethylanimobenzaldehyde (Fluka)3%, weighing 3 g and dissolved in 100 ml methanol in a volumetric flask. All other reagents were prepared by dissolving the propriety weight in perfect solvent. A volume in the range of 0.1 to 1.7 ml of 100 µg.ml-1RNICS solution was transferred to 10 ml calibrated flasks.2ml of PNNDMABA (3.0 %) was added, and the volume was made up to 10 ml by adding methanol. The yellow Schiff's base was measured at 454 nm versus a blank solution. Results and Discussion:The optimum pH for reaction of NICS with para-N, N- dimethylanimobenzaldehyde equal to 3 which resulted by mixing the components of the reaction. The absorbance increase with increasing reagent concentration (para-N,N- dimethylanimobenzaldehyde) and reached maximum on adding volume of 2.0 ml of (3%), which also gives the highest value of determination coefficient (R2).The experimental data indicated that methanol was the optimum solvent used in dilution according to high intensity of Schiff's base and the good stability. The formation of the yellow Schiff's base being complete after mixing the components of reaction and the absorbance remained constant for at least 2 hours. Conclusion: Accurate and sensitive spectrophotometric method was described for the estimation of NICS. The present method has been successfully applied for the estimation of NICS in pharmaceutical and veterinary preparations.