Finding Ascorbic Acid

August 26/Journal of Technology & Science -- According to a study from Karachi, Pakistan, "Ascorbic acid (AA) is one of the most important water soluble vitamin in the human diet, present naturally in a wide range of foods, especially fruits and vegetables. The objectives of this study was to develop a rapid, sensitive and specific method for the determination of ascorbic acid (vitamin C) from a variety of sources like fresh fruits or from human plasma using spectrophotometric technique or by RP-HPLC."

"Initially, estimation of vitamin C was carried out spectrophotometrically as UV spectroscopy is a trusted technique to monitor small quantities of drugs and vitamins. The assay was linear over the concentration range of 0.05-100 mu g/mL(-1). In the second procedure, we attempted to separate and quantitate ascorbic acid from fruit juices as well as from human plasma by RP-HPLC with UV detection. This has been possible because of the diversity of columns and conditions of analysis available. Chromatographic separation was successfully achieved on a pre-packed Kromasil 100, C-18 (5 mu m 25 x 0.46) column using acetonitrile: water (60:40; v/v) as mobile phase at a flow rate of 0.75 mL(-mm) and effluent monitored at 265 nm. The assay was also linear over the concentration range of 0.05-100 mu g/mL(-1), with recovery ranging from 99.0-100.0% and intra and inter day CV <3% when applied to the analysis of ascorbic acid from fruit juice available in Pakistan at the time of study," wrote M.S. Arayne and colleagues, University of Karachi.

The researchers concluded, "Grape fruit, malta, mosami, sweetlemon, fruiter, lemon, lime, custard apple, orange, lemon, guava and papaya juice were found to be very rich in as ascorbic acid, while chikoo, pear, apricot, peach, carrot and some other fruits were found to be poor sources of ascorbic acid."

Arayne and colleagues published the results of their research in the Journal of the Chemical Society of Pakistan ("Rapid and Specific Spectrophotometric and RP-HPLC Methods for the Determination of Ascorbic Acid in Fruits Juices and in Human Plasma." Journal of the Chemical Society of Pakistan, 2009;31(3):402-407).

For additional information, contact M.S. Arayne, University of Karachi, Dept. of Chemical, Karachi 75270, Pakistan.

From the August 31, 2009, Prepared Foods E-dition