Indirect determination of ascorbic acid (vitamin C) by spectrophotometric method

• Published in: International journal of food science & technology Vol. 42; no. 12; pp. 1402 - 1407
• Main Author: Nejati-Yazdinejad, Massoud
• Format: Journal Article
• Language: English
• Published: Oxford, UK Oxford, UK : Blackwell Publishing Ltd 01.12.2007; Blackwell Publishing Ltd; Blackwell Science
• Subjects: Alizarin red s; ascorbic acid; Biological and medical sciences; Cu (II) ion; Food industries; foods; Fundamental and applied biological sciences. Psychology; indirect determination; pharmaceutical preparations; spectrophotometric; Ascorbic acid; pharmaceutical preparations; foods; Cu (II) ion; Vitamin; Ions; Method; Alizarin red s; indirect determination; Red; Preparation; Spectrophotometry; spectrophotometric; Food
• ISSN: 0950-5423; 1365-2621
• DOI: 10.1111/j.1365-2621.2006.01353.x

A novel spectrophotometric method is described. The procedure involves the use of Cu (II) as vitamin C oxidant. After completion of oxidation reaction, excess of Cu (II) is determined by complexation with alizarin red s (ARS). Thiocyanate ion is used as stabilising agent for Cu (I) which is the product of oxidation reaction. This method is used for determination of vitamin C in fruits and pharmaceutical products. Linearity was found to be perfect in the range 3.5 x 10⁻⁶-4.8 x 10⁻⁵ m (0.6-8.2 ppm). The detection limit and relative standard deviation of method are 2.0 x 10⁻⁶ m (0.35 ppm) and 1.03%, respectively. The proposed method is simple, safe, inexpensive and rapid.