Abstract:

Objective: To establish a method for the fast determination of raffinose in food and oligosaccharide by the combined use of thin layer chromatography (TLC) and phenol-sulfuric acid method. Methods: For the separation of raffinose, the developing solvent used was a mixture of methyl cyanides, acetic acid and water (6:3:2, V/V), and the chromogenic agent was composed of aminobenzene, diphenylamine and phosphoric acid, and the sample loading volume was 5 μL. The separated raffinose brand was harvested and analyzed by phenol-sulfuric acid method. Results: Different components of soybean oligosaccharide (sucrose, raffinose and stachyose) could be well separated by using TLC. The standard curve developed for raffinose determination by phenol-sulfuric acid method presented a linear range from 20 to 80 mg/mL (R2 = 0.9932). The precision RSD for raffinose determination was 1.56%. The method spike recovery was 98.14%, with a RSD of 3.99%. The relative error between the results of determination by this method and HPLC was 3.22%. This method is applicable to the determination of raffinose in food and oligosaccharide.

Key words: soybean oligosaccharide, raffinose, TLC, phenol-sulfuric acid method