1, the conventional method
The ethanol solution of the color reaction A sample should be pure yellow and have a light green fluorescence; if the ethanol extract is added to concentrated sulfuric acid, a deep purplish red color is produced. Color Reaction B The aqueous solution or dilute ethanol solution of the sample was treated with hydrochloric acid until it started to be slightly orange.
The mixture was divided into two portions, and a small amount of boric acid powder or crystal was added to one portion, and its color was significantly reddened compared to the portion without boric acid. It is also possible to immerse several pieces of filter paper in a solution of the pigment in ethanol, dry at 100 ° C, and then wet with a dilute solution of boric acid (with a few drops of hydrochloric acid). It should be cherry red after drying.
Take 5 ml of the test solution (0.01 g sample dissolved in 1 mL of 95% ethanol) and drop on a thin layer chromatography (microcrystalline cellulose, 0.1 mm) and place it in 3-methyl-1-butanol/ethanol/water/ In the developing tank of the ammonia (4:4:2:1) mixture, the solvent front edge is raised by 10 to 15 cm. After a day and night, it was observed under ultraviolet light: there were three yellow spots with Rf between 0.2 and 0.4; the other spots had an Rf of 0.6 to 0.8; all spots showed yellow fluorescence under ultraviolet light. The 6.95% ethanol solution has a maximum absorption peak at 425 nm.
Curcumin system solution
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