1, vitamin A naked eye as a light brown or grayish yellow particles. Sampling was 0.1 g, wet grinding with anhydrous ethanol to dissolve, add 10 ml of chloroform, the chloroform solution plus 0.5 ml of antimony trichloride solution was blue before and immediately fade, is genuine.
2, vitamin E powder appearance of white or light yellow powder. Take 15 mg of sample, add 10 ml of ethanol after it dissolved, add 2 ml of nitric acid, shake heated 15 minutes, was dissolved orange-red as authentic.
3, vitamin E, sodium selenite powder appearance of white or off-white powder. Take samples 0.5 g, add 30 drops of ethanol shaking filtration, the filtrate was added 5 drops of nitric acid, heated to red party is genuine.
4, vitamin K3 appearance of white or gray-brown crystalline powder. Take samples 0.1 g, add 10 ml of water to dissolve, add 3 ml of sodium carbonate solution has bright yellow precipitate was genuine.
5, vitamin B1 appearance of white crystal or crystalline powder, slight odor, slightly bitter flavor. 0.1 g samples were taken, shaken a little water, filtered, the filtrate 3 drops of iodine reagent, brown-red precipitate formed.
6, Vitamin B2 appearance of yellow to orange yellow crystalline powder, bitter smell, take samples 0.5 g, was dissolved a little water, the supernatant, dilute hydrochloric acid or sodium hydroxide solution was added 2 drops of yellow fluorescent supernatant disappear.
7, 0.1 g of ferrous sulfate samples taken, dissolved in 10 ml of water, whichever is the solution was added 2-3 drops of a 10% iron chloride solution to produce a dark blue precipitate, adding a few drops of dilute hydrochloric acid, the precipitate is poorly soluble is genuine.
8, 1 g of magnesium sulfate to take a sample, dissolved in 10 ml of water, adding aqueous ammonia to a white precipitate, the precipitate is dissolved by adding appropriate amount of ammonium chloride was added 5% disodium hydrogen phosphate solution, the white precipitate formed, which does not dissolve after adding ammonia.