A flow injection-spectrophotometric method has been presented for the simple, rapid and sensitive determination of L-ascorbic acid. The method is based on the reduction of Fe(III) by L-ascorbic acid and subsequent formation of coloured Fe(II) complex with 1, 10-phenanthroline which is monitored spectrophotometrically at 510 nm. The calibration curve was rectilinear up to 1.0 × 10
-5 M L-ascorbic acid when 5.0 × 10
-5 M Fe(III) and 2.5 × 10
-4 M 1, 10-phenanthroline solutions were propelled with the flow rates of 0.55 ml/min and 0.25 ml/min, respectively, and 100μl sample was injected into the carrier stream. The method has a limit of detection of 2.5 × 10
-7 M and permits
ca. 70 determinations per hour with a relative standard deviation of 1.8% for 5.0 × 10
-6 M solution. In the analysis of fresh fruit juices and fruit drinks, the samples were filtered and suitably diluted before injection. The results by the proposed method were well agreed with those by the titration method with 2, 6-dichlorophenolindophenol.
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