Optical fiber chemiluminescence biosensor for antioxidants based on an immobilized luminol/hematin reagent phase

A chemiluminescence (CL) biosensing system for antioxidants was developed b ased on luminol and hematin co-immobilized on a cellulose membrane disc. Th e concentration of the antioxidant was quantified through the measurement o f the inhibition of the CL emitted when hydrogen peroxide was introduced in to the reagent phase. The instrumentation employed in the measurement was a fabricated luminometer employing optical fibers and a UV-enhanced photodio de transducer. Under optimum conditions, linear calibration curves were obt ained for antioxidant concentrations ranging from 1 x 10(4) M to 0.10 M, wi th an average relative standard deviation of about 5%. The minimum detectab le concentration was 100 mu M, and the response time was less than 60 secon ds. The sensor response correlated well (r = 0.9979) with the results of a standard colorimetric method for a specific antioxidant (propyl gallate), T he sensor was used to assess the antioxidant capacity of water infusions pr epared from the dried leaves of some Philippine medicinal plants.