Solanine is widely found in solanaceae plants, such as potatoes, tomatoes and eggplant. Although the content of solanine in potato varies with varieties and seasons, it is generally 0.005%~0.0 1%, which gradually increases during storage. After the potato germinates, the solanine content in the bud and eyes is as high as 0.3%~0.5%. The oral toxicity of solanine is low, and human consumption of 0.2~0.5g solanine can cause poisoning. Solanine can be determined by chemical chromogenic method. The principle and operation steps of chemical coloration method are as follows:

[Scope of application]

Solanaceae plant foods such as potatoes, tomatoes and eggplant.

[Detection principle]

Solanine can react with ammonium vanadate and sodium selenate, and its color changes with time, which is the characteristic reaction of solanine. At the same time, solanine can also react with concentrated nitric acid and concentrated sulfuric acid for redox color reaction.

[reagent]

① Ammonium vanadate solution Weigh 1g ammonium vanadate and dissolve it in 1: 1000 sulfuric acid aqueous solution.

② Sodium selenate solution Weigh 0.3g sodium selenate, dissolve it in 8mL water, then add 6mL sulfuric acid, and mix well.

[Operation Steps]

Mash a proper amount of sample, juice it, put it in a beaker, wash the residue with water, mix the lotion with the juice, and take the supernatant.

Ammonia water is alkalized and evaporated to dryness. The residue was extracted twice with 95% hot ethanol, filtered, and the filtrate was alkalized with ammonia to precipitate solanine, and then filtered and precipitated.

Add a small amount of precipitate to 1 ml ammonium vanadate solution and observe the color change.

Add a small amount of precipitate to 1 ml sodium selenate solution, heat and cool, and observe the color change.

Cut the sprouting part of potato, drop concentrated nitric acid and concentrated sulfuric acid into the sprouting part respectively, and observe the color change.

[Result confirmed]

(1) Add 1mL ammonium vanadate solution, it turns yellow, then gradually turns orange-red, purple, blue and green, and finally the color disappears.

(2) adding 1mL sodium selenate solution, heating, cooling, turning purple, then orange red, yellow orange yellow, yellow brown, and finally the color disappears.

(3) drop concentrated nitric acid and concentrated sulfuric acid, rose red.

[Notes]

Pay attention to the safety of the experiment, and use concentrated sulfuric acid and concentrated nitric acid with caution during the experiment.