This article from Issue 14 of the Analytix Reporter shows a fast, economic, and easy screening approach by simultaneous analysis of ascorbic acid and dehydroascorbic acid in various food samples by high performance thin layer chromatography (HPTLC).
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Introduction
Vitamin C or ascorbic acid is a vitamin found naturally in many fruits and some vegetables or is added to certain processed foods or dietary supplements. It is water-soluble and has antioxidative capacities by degrading to dehydroascorbic acid. The human organism cannot produce ascorbic acid and it must be ingested through food or supplements. It has essential functions in the human body and maintains numerous vital processes. When vitamin C is deficient (scurvy), symptoms can occur such as fatigue, tiredness, and inflammations. The recommended daily dose of ascorbic acid is about 100 mg per day and can easily be reached with a healthy, balanced diet. Typically, ascorbic acid is quantified by iodometric titration according to a USP method. An additional substance identification is required and performed by infrared analysis, for example.
In the following application, we show an easy and fast screening approach for the simultaneous quantitative analysis of ascorbic acid and dehydroascorbic acid by high performance thin layer chromatography (HPTLC). Thin layer chromatography (TLC) and HPTLC are convenient, fast, and efficient separation techniques that enable the development of analytical methods without the need for extensive sample preparation or high investments. When combined with MS, a subsequent substance identification is possible. Low cost and short analysis time per sample are given by the parallel analysis of ascorbic acid in food products on one plate. Furthermore, the high matrix tolerance of TLC offers additional opportunities to existing routine methods. The high viscosity and high sugar content of many ascorbic acid products (e.g. fruit juice) makes them very complex and matrix-rich samples to analyze.
Experimental Conditions
Five different commercially available ascorbic acid containing products, such as juice concentrate, fruit gums, vitamin C effervescent tablet, multi vitamin effervescent tablet, and a tablet with cranberry extract were analyzed using conditions shown in Table 1 (see full article).
Results and Discussion
At 366 nm illumination, ascorbic acid appears at hRf 45 and dehydroascorbic acid at hRf 58 (see Figure 2 in the article). MS measurement of the spots (before heating) were carried out to confirm substance identification.
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