Flow-injection amperometric determination of dopamine in pharmaceuticals using a polyphenol oxidase biosensor obtained from soursop pulp

• Published in: Journal of pharmaceutical and biomedical analysis Vol. 33; no. 5; pp. 1025 - 1031
• Main Authors: Bezerra, Vilma Sobral, de Lima Filho, José Luiz, Montenegro, Maria Conceição B.S.M, Araújo, Alberto N, da Silva, Valdinete Lins
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 04.12.2003; Elsevier Science
• Subjects: Amperometry; Analysis; Analytical, structural and metabolic biochemistry; Annona; Annona muricata; Biological and medical sciences; Biosensing Techniques - instrumentation; Biosensing Techniques - methods; Biosensing Techniques - standards; Biosensor; Catechol Oxidase - analysis; Dopamine; Dopamine - analysis; Electrochemistry; Flow Injection Analysis - methods; Fundamental and applied biological sciences. Psychology; General pharmacology; Medical sciences; Pharmaceutical formulations; Pharmaceutical Preparations - analysis; Pharmacology. Drug treatments; Polyphenol oxidase; Amperometry; Dopamine; Biosensor; Polyphenol oxidase; Pharmaceutical formulations; Enzyme; Catechol oxidase; Catecholamine; Neurotransmitter; Dosage form; Oxidoreductases; Quantitative analysis; Flow injection
• ISSN: 0731-7085; 1873-264X
• DOI: 10.1016/S0731-7085(03)00412-6

The amperometric determination of dopamine (Do) in pharmaceuticals formulations by flow injection analysis (FIA) is proposed. An enzymatically modified carbon paste electrode constituted by 25% (w/w) of polyphenol oxidase obtained from Annona muricata L. tissue, 30% (w/w) of graphite, 30% (w/w) of silicone and 15% (w/w) of 7,7,8,8 tetracyanoquinodimethane (TCNQ), was used as flow-through detector. The flow amperometric detection was carried out at a potential of 0.10 V (vs. Ag/AgCl) when an injected sample volume of 250 μl was inserted on a 0.3 M phosphate buffer carrier solution (pH 7.8) flowing at 2.5 ml/min. The developed biosensor showed good stability and reproducibility, enabling up to 500 determinations in 60 days, without considerable loss of enzymatic activity. The FIA system presented a linear response to Do concentrations in the interval from 2×10 −2 to 2×10 −4 M, with relative standard deviations lower than 1.5%. The kinetic parameter K M for the soluble and immobilized enzyme was 1.45×10 −2 and 1.91×10 −2 M, respectively. In the analyses of different commercially pharmaceutical formulations a relative deviation lower than about 3.4% was obtained.