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Spectrophotometric methods for the determination of L-tyrosine in pharmaceutical formulations

Banan Elshiekh Alsied Basheir, Abdalla A.Elbashir

New simple and sensitive spectrophotometric method has been developed and validated for the determination of L-tyrosine in pharmaceutical formulations. The spectrophotometric method was based on the reaction of L-tyrosine with 4- chloro-7-nitrobenzo-2-oxa-1,3-diazole (NBD-Cl) in an alkalinemedium(pH10.0) to forman orange product absorbers at 388 nm. The variables affecting the reaction of L-tyrosine with NBD-Cl was carefully studied and optimized.Under the optimumreaction conditions, good linear relationships were found between the readings and the concentrations of Ltyrosine in the ranges 10-50 ìg/mL. The limit of detection (LOD) and limit of quantification (LOQ) were found to be 2.85 ìg/mL and 8.6 ìg/mL, respectively. The method was successfully applied to the determination of L-tyrosine in its pharmaceutical formulations.