title: Kinetic approach for the enzymatic determination of levodopa and carbidopa assisted by multivariate curve resolution-alternating least squares.
abstract: A combination of kinetic spectroscopic monitoring and multivariate curve resolution-alternating least squares (MCR-ALS) was proposed for the enzymatic determination of levodopa (LVD) and carbidopa (CBD) in pharmaceuticals. The enzymatic reaction process was carried out in a reverse stopped-flow injection system and monitored by UV-vis spectroscopy. The spectra (292-600 nm) were recorded throughout the reaction and were analyzed by multivariate curve resolution-alternating least squares. A small calibration matrix containing nine mixtures was used in the model construction. Additionally, to evaluate the prediction ability of the model, a set with six validation mixtures was used. The lack of fit obtained was 4.3%, the explained variance 99.8% and the overall prediction error 5.5%. Tablets of commercial samples were analyzed and the results were validated by pharmacopeia method (high performance liquid chromatography). No significant differences were found (alpha=0.05) between the reference values and the ones obtained with the proposed method. It is important to note that a unique chemometric model made it possible to determine both analytes simultaneously.
authors.affiliation: FIA Laboratory, Department of Chemistry, Universidad Nacional del Sur, INQUISUR (UNS-CONICET), Av. Alem 1253 (B8000CPB), Bahía Blanca, Buenos Aires, Argentina.
authors.forename: Marcos
authors.initials: M
authors.lastname: Grünhut
authors.forename: Mariano
authors.initials: M
authors.lastname: Garrido
authors.forename: Maria E
authors.initials: ME
authors.lastname: Centurión
authors.forename: Beatriz S
authors.initials: BS
authors.lastname: Fernández Band
mesh_terms: D002138:Calibration; D002230:Carbidopa / Q000032:analysis* / Q000378:metabolism; D004156:Catechol Oxidase / Q000378:metabolism; D004867:Equipment Design; D027723:Ipomoea batatas / Q000201:enzymology; D007700:Kinetics; D016018:Least-Squares Analysis; D007980:Levodopa / Q000032:analysis* / Q000378:metabolism; D015999:Multivariate Analysis; D004364:Pharmaceutical Preparations / Q000737:chemistry*; D012016:Reference Values; D013053:Spectrophotometry / Q000191:economics / Q000295:instrumentation / Q000379:methods
chemical_list: D004364:Pharmaceutical Preparations; D007980:Levodopa; D004156:Catechol Oxidase; D002230:Carbidopa