I have synthesized the carbohydrate compounds and want to know how can i determine or recognize them using TLC tool?
Dear Mohammad, you will find as many stains as you will find chemists.
In general, carbohydrates, deep your tlc in 5% sulfuric acid in methanol or ethanol. then "burn" the tlc using a heat gun, most likely, the brown spots are you carbohydrate containing derivatives.
good luck
Another one is a cocktail of aniline (4 mL) + acetone (96 mL) + diphenylamine (4 g) + 20% phosphoric acid (20 mL) (in listed order). Your sugar should stain a nice brown when you dip and heat the tlc with this stain. This method is also great for very low concentrations of sugar.
Dear Laurent and David, thank you to for the helpful comments, I'll test both of them. Hope the methods meet my requirements.
Use iodine chamber, or permanganate. Phosphomolybdic acid is also an alternative.
I think iodine chamber is most suitable.
You may also use Reverse Phase TLC for better resoultion of results, As carbohydrated are very polar molecule.
Mohammad: don't forget to use some standards as well in your TLC run. Try to use TLC plates with no F indicator. The development of the spots succeeds best with the BAW variation mixture of n-butanol-acetic acid-ethyl ether-water 9:6:3:1. You can spray the TLC using the anisaldehyde reagent: 0.5 mL of anisaldehyde in 9 mL of EtOH 95%, 0.5 mL of concentrated sulfuric acid and 0.1 mL of acetic acid (in a fume hood!). Sucrose gives violet (Rf 0.09), Glucose blue (0.22), Fructuose violet (0.27).
Cheers!
Dear Giselle, many thanks for your comments. i will try to test it.
orcinol would be another sensitive detection reagent:
take 180 mg orcinol (e.g. Sigma), dissolve in 5 ml of water, add 75 ml EtOH and cool on ice. Then add slowly under constant stirring 10 ml H2SO4 conc. Keep the reagent in the dark (wrapped in foil) at 4 oC. When you spray the TLC plate with this reagent, carbohydrates will be detected as purple spots / bands upon heating (with a heat gun or in an oven).
Dear Mohammad,
Reagent: 2 g 4-aminobenzoic acid are added to a mixture of 36 mL acetic acid, 40 mL water, 2mL
phosphoric acid (85%) and 120 mL acetone.
The dried plate is immersed in the reagent using the CAMAG Immersion Device (speed 1, time 2), airdried, then heated on the plate heater or in an oven at 115°C for 15 minutes. Oligosaccharides
appear as yellow-brown spots on a pale yellow background.
Another one is a cocktail of aniline (4 mL) + acetone (96 mL) + diphenylamine (4 g) + 20% phosphoric acid (20 mL) (in listed order). Spray the plate with this cocktail and Keep the plate in oven at 90℃ for 1 hour. The spots will develop as blue and pink colors for different carbohydrates. Be careful while using orthophosphoric acid as it can burn skin and clothes.
Molisch's stain works well for carbohydrate detection on TLC plates.The
sugars developed on the plates can be visualised by heating at 110 °C for 10 min after soaking in Molisch's Reagent (0.3% (w/v) α-naphthol dissolved in sulfuric acid: methanol solution (5: 95, v/v)).
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