HIGHLY SELECTIVE FLOW-INJECTION SPECTROPHOTOMETRIC DETERMINATION OF ASCORBIC ACID IN FRUIT JUICES AND PHARMACEUTICALS USING PYROGALLOL RED-IODATE SYSTEM

ABSTRACT

Ascorbic acid present in pharmaceuticals and fruit juice was rapidly determined by the spectrophotometric method in association with flow injection analysis. The method is based on the inhibitory effect of ascorbic acid on the oxidation of pyrogallol red by iodate in sulfuric acid media. The calibration graph is linear in the range of 2.0 × 10⁻⁶ M up to 1.0 × 10⁻⁴ M. The throughput is 20 × 5 samples per hour and the detection limit is 0.5 µM ascorbic acid. The relative standard deviation for ten replicate determinations of 8.00 µM and 50.0 µM ascorbic acid is 3.4 and 0.60%, respectively. The influence of various species was studied for this determination.

Keywords:

• Ascorbic acid
• FIA
• Iodate
• Pyrogallol red
• Spectrophotometry

Acknowledgment

The authors acknowledge the Research Council of Isfahan University of Technology and Center of Excellency in Chemistry of Isfahan University of Technology for the support of this work.