Carriers for TLC Preparation (Silica Gel, Polyamide)

1. Type of carrier
   

   Unmodified silica gel	Used in adsorption chromatography mode, mainly suitable for separation of acidic or neutral compound.
   Chemically modified silica gel	Various functional groups are bonded to the silanol groups on the surface of unmodified silica gel to change the function. C18 modified silica gel, which is octadecyl group (ODS) bonded silica gel, suitable for reversed-phase chromatography mode. NH2 modified silica gel, which is aminopropyl group bonded silica gel, suitable for separation of sugars, catecholamines, etc.
   Polyamides	Used in adsorption chromatography mode, suitable for separation of phenols and carboxylic acids.
   Alumina	Used in adsorption chromatography mode, suitable for separation of basic compounds.
   Cellulose	Used in normal phase chromatography mode, suitable for separation of hydrocarbon compounds.

2. Pore size/specific surface area
   The smaller the pore size, the greater the specific surface area of the silica gel and the higher the resolution of small molecules. Conversely for macromolecules such as proteins, the larger the pore size, the higher the resolution. It is necessary to select an appropriate pore size so that sample molecules can easily enter and exit the pores.
3. Type of support
   Glass has excellent chemical resistance and is the most widely used. Aluminum and paper can be cut easily with scissors, but the carrier peels off from support or the TLC bends depending on the developing solvent. In addition, strong acids/bases cannot be used as developing solvents or coloring reagents.
4. Type of fluorescent substance
   

   Not contain	It is suitable for detection of fluorescing samples and spot detection using coloring TLC stains (sulfuric acid, ninhydrin, iodine, etc.) because it does not contain fluorescent substances.
   Mono fluorescent substance	254 nm UV irradiation causes the entire plate to fluoresce green, and samples with UV absorption turn black colored spots.
   Mixture fluorescent substance	Red, green and blue fluorophores substance are added. Under broadband UV (250-400 nm) irradiation causes the entire plate to white, and samples with UV absorption turn the characteristic colored spot such as, red, blue, etc.

Silica gel can be used to making TLC plates on glass plates by prescribed operations. It is mainly used for separating acidic or neutral substances, and when the sample is neutral substance and has 1-2 functional groups, it is developed in a single or mixed mobile phase using an activated thin layer. Add a small amount of ammonia or diethylamine to the developing solvent if the sample is an organic base substance. Add a small amount of acetic acid to separate acidic substance. If the developing mobile phase contains water, mix with water and create a thin layer. Wakogel^® B Series does not need to be heated to activate.

The number after B- in the product name indicates the binder (adhesive) content. In addition, F indicates the addition of a single fluorescent substance, and FM indicates the addition of three mixture fluorescent substances.

Polyamides are polymers with carboxamide bonds (-CONH-). Polyamide is neutral and has a larger adsorption capacity than inorganic adsorbents. It shows very good separation of DNP amino acids, glycosides, carboxylic acids, aromatic nitro compounds, and especially phenols (simple phenols, bromophenols, and phenolic alkaloids, etc.).