info:eu-repo/semantics/article
Enzymatic flow injection analysis of coprostanol in non-aqueous media
Autor
Piñeiro Avila, Gerardo
Salvador, Amparo
De la Guardia, Miguel
Institución
Resumen
An alternative method has been developed for the spectrophotometric determination of coprostanol in sediments, based on its extraction with chloroform-methanol(2+1 v/v) and enzymatic analysis in pH 7.0 buffer saturated toluene, using a bienzymic reactor prepared with 1 mg cholesterol oxidase (23 IU) and 1 mg horseradish peroxidase (220 PU) both noncovalently immobilised on controlled pore glass beads. The method allow us to determine coprostanol in a dynamic range from 2.2xl0-4 M to 9x10-4 M , measuring the absorbance at 458 nm of the oxidized form of p-anisidine. The relationship between absorbance (A) and coprostanol concentration (C) expressed in mol.L-1 was A = (0.0059 Ó 0.0005) + (17 Ó 1) (C) with a r2 = 0.998 and it was obtained a limit of detection of 7x10-6 M in the best experimental conditions. Recovery studies carried out on water and beach sediments, at concentration levels from 0.1 to 0.25 mg.g1, provided values from 96 to 112%.