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Determinação enzimática de dopamina em formulações farmacêuticas utilizando sistema de análise por injeção em fluxo com extrato bruto de abacate (Persea americana)

2003; Brazilian Chemical Society; Volume: 26; Issue: 2 Linguagem: Inglês

10.1590/s0100-40422003000200010

1678-7064

Karina Omuro Lupetti, Luiz Antônio Ramos, Orlando Fatibello‐Filho,

Agricultural and Food Sciences

AVOCADO (Persea americana) CRUDE EXTRACT.In this work, a spectrophotometric flow injection analysis system using a crude extract of avocado (Persea americana) as a source of polyphenol oxidase to dopamine determination was developed.The substrates and enzyme concentrations from 2.4x10 -7 to 5.3x10 -4 mol L -1 and 28 to 332 units mL -1 were evaluated, respectively.In addition, the FIA parameters such as sample loop (50 to 500 µL), flow rate (1.4 to 4.3 mL min -1 ) and reactor length (100 to 500 cm) were also evaluated in a 0.1 mol L -1 phosphate buffer solution (pH 7.0).Dopamine solution concentrations were determined using 277 units mL -1 enzyme solution, 400 mL enzyme loop, 375 µL sample loop, 2.2 mL min -1 flow rate and a reactor of 350 cm.The analytical curve showed a linearity from 5.3x10 -5 to 5.3x10 -4 mol L -1 dopamine with a detection limit of 1.3x10 -5 mol L -1 .The analytical frequency was 46 h -1 and the RSD lower than 0.5% for 5.3x10 -4 mol L -1 dopamine solution (n=10).A paired t-test showed that all results obtained for dopamine in commercial formulations using the proposed flow injection procedure and a spectrophotometric procedure agree at the 95% confidence level.