Simultaneous kinetic-spectrofluorometric determination of levodopa and carbidopa using partial least-squares regression.
A simple and sensitive methodology for the simultaneous determination of levodopa and carbidopa in pharmaceutical samples is described. The method combines the advantages of fluorescence with partial least-squares (PLS) analysis, and requires no previous separation steps. The developed method is based on the oxidation of levodopa and carbidopa by cerium(IV) in a sulfuric acid medium and monitoring the fluorescence of the formed Ce(III) at lambda(exc) = 255 nm and lambda(em) = 355 nm. PLS uses differences in the reaction rates as a discriminatory parameter, and regresses the data of fluorescence vs. time onto the concentrations of the standards. Eight validation samples and seven commercial tablets were studied, using a nine-sample aqueous calibration set. The analyte recoveries from pharmaceuticals ranged from 98 to 101% for levodopa and from 100 to 108% for carbidopa. The results obtained by the developed method were statistically comparable to those obtained with high-performance liquid chromatography.
Departamento de Química Analítica, Facultad de Ciencias Bioquímicas y Farmacéuticas, Universidad Nacional de Rosario and Instituto de Química Rosario, Consejo Nacional de Investigaciones Científicas y Técnicas, Rosario S2002LRK, Argentina.
Ariana P
AP
Pagani
Miguel A
MA
Cabezón
Gabriela A
GA
Ibáñez
D000978:Antiparkinson Agents / Q000032:analysis*; D002230:Carbidopa / Q000032:analysis*; D002563:Cerium / Q000737:chemistry; D005453:Fluorescence; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D016018:Least-Squares Analysis; D007980:Levodopa / Q000032:analysis*; D010084:Oxidation-Reduction; D004364:Pharmaceutical Preparations / Q000737:chemistry; D013050:Spectrometry, Fluorescence / Q000379:methods*; D013464:Sulfuric Acids / Q000737:chemistry; D013696:Temperature
D000978:Antiparkinson Agents; D004364:Pharmaceutical Preparations; D013464:Sulfuric Acids; D002563:Cerium; D007980:Levodopa; D002230:Carbidopa; C033158:sulfuric acid