Also, how does this help develop sugars on the plate?
The order of strength/weakness depends on the coating (stationary phase) of the TLC plate. For silica gel-coated TLC plates, the eluent strength increases in the following order: perfluoroalkane (weakest), hexane, pentane, carbon tetrachloride, benzene/toluene, dichloromethane, diethyl ether, ethyl acetate, acetonitrile, acetone, 2-propanol/n-butanol, water, methanol, triethylamine, acetic acid, formic acid (strongest)
The solvents you mentioned do not react with the sugar(s) but because of their polarity and the solubility of the sugars are responsible for the relative retention time of the spot(s).
It is the spray you use that 'visualize' the spot(s). It is this spray that reacts with the sugar(s).
Dear Isabel,
As explained nicely by Bruce, there are no chemical reaction involved with the chromatography of sugars involving the following solvent system. The solvents CH3COOH & water are highly polar protic solvents while butanol is amphiphilic and DEE is relatively less polar among all. So the mixture of solvents offer a varying polarity which in turn reflects the retention behavior of analytes on the stationary phases. The developer mentioned herein is mainly used for the separation of strongly polar substances.
The main reaction happens when the visualisation or derivatisation reagent is being applied on TLC at post-chromatographic derivatisation which undergoes some preliminary reaction that is visualised as observable colors or spots in TLC.
The question is how much do you want to resolve these carbohydrates. I doubt that TLC has the resolving power to separate these molecules (check the online journals). HPLC can separate them but it is expensive.
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