1. Preparation of test solution:
Take 3g of oleander leaf pieces, add 40ml of 70% ethanol in a 100ml Erlenmeyer flask, dip for 5 minutes on a water bath, let cool, filter, and filtrate (or after treatment - refer to Note 2) for identification .
[Note 1]: The test of cardiac glycosides is carried out under strong alkaline conditions. If the sample contains strontium, it also has a red reaction, which hinders the inspection. Therefore, it is necessary to check the presence or absence of mites before inspection. The composition, if any, should be removed first, that is, the ethanol immersion liquid is evaporated on the water bath, the residue is added with CHCl3 and then dissolved, and the CHCl3 solution is shaken with 1% NaOH solution to remove the hydrazine, and the CHCl3 solution is used for identification.
[Note 2]: Oleander leaves or foxglove chlorophyll often cause the alcohol extract to have a darker green color, which affects the progress of the reaction. Therefore, chlorophyll needs to be removed, as follows:
The ethanol extract is used to remove most of the ethanol in the water bath (not letting the ethanol flow), and then add the appropriate amount of water to make the alcohol content about 20%. After a little heat, it is allowed to cool and filtered, and the filtrate is ready for testing, or The filtrate was concentrated to a syrup on a water bath, and dissolved in 10 ml of 95% ethanol for testing.
2. Identification test:
(1) Ferric chloride glacial acetic acid reaction (Keller-Kiliani reaction): take the alcohol extract or the treated CHCl3 or alcohol solution 1ml, evaporate to dryness on a water bath, dissolve the residue in 2ml of glacial acetic acid, add 1% FeCl3 ethanol 1 drop of liquid, mix well, pour into the dry small test tube, then slowly add an equal volume of concentrated sulfuric acid along the tube wall, and let it stand. The two liquid junctions show brown (glycosides), gradually change to light green, blue, and finally acetic acid. The layers are all blue or blue-green (-deoxy sugar).
(2) Alkaline 3.5-dinitrobenzoic acid reaction (Kedde reaction): 1 ml of an alcohol extract is added, and 3 to 4 drops of an alkaline 3.5-dinitrobenzoic acid reagent are added to produce a red or reddish purple reaction.
(3) Sodium nitrosyl ferricyanide reaction (Legal reaction): 1 ml of the alcohol extract or the treated CHCl3 or alcohol solution is evaporated to dryness on a water bath, and the residue is dissolved in 1 ml of pyridinium, and 0.3% nitrosyl group is added. 4~5 drops of sodium ferricyanide solution, mix well, add 1-2 drops of NaOH saturated ethanol solution, whether it is red. If the result is not obvious, take another test solution as above, and finally add NaOH saturated ethanol solution. 0-5ml, observe the presence or absence of red at the interface of the two liquids.
(4) Basic picric acid (Baljet reaction)
Take 1 ml of the sample alcohol solution, add a few drops of alkaline picric acid reagent (bitter acid saturated water and 5% NaOH water), and present orange or orange red.
Freeze Dried Pea
Pea tips can be eaten by the general population, and there are no special contraindications. Unless people are allergic to peas, it is not recommended to eat them.
Finally, I remind everyone that when buying pea tips, the more tender the better, and try not to cut them with a knife when frying, which will cause the loss of nutrients. You can add a small amount of water when frying, also to prevent the water from the pea tips. , In addition, the stems and leaves of pea sprouts are tender and have high moisture content, so they need to be sealed and stored.
Nutrition experts said: Eating pea tips often has the effect of detoxification and liver protection, because it contains a lot of magnesium and chlorophyll, which helps to expel toxins from the body and protect the liver.
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