Vanillin-sulfuric acid reagent

Most of the thiazoles studied absorb in the ultraviolet above 254 nm, and the best detection for these compounds is an ultraviolet lamp (with plates containing a fluorescent indicator). Other indicator systems also exist, among which 5% phosphomolybdic acid in ethanol, diazotized sulfanilic acid or Pauly s reagent (Dragendorff s reagent for arylthiazoles), sulfuric anisaldehyde, and vanillin sulfuric acid followed by Dragendorff s reagent develop alkylthiazoles. Iodine vapor is also a useful wide-spectrum indicator. 

Vollmann et.al reported the TLC determination of eugenol in mixtures containing bomeol, norphinon, and myrtenol as components of Geum urbanum [20]. The method uses silica gel as the stationary phase, and 3 1 pentane-ether as the mobile phase. Detection is effected on the basis of the UV absorbance at 366 nm, and by spraying with vanillin-sulfuric acid reagent and heating at 120°C for 10 minutes. 

Practical Tip Do not leave your fingerprints on the plates These can become clearly visible after derivatization by some reagents, e.g., ninhydrin or vanillin-sulfuric acid reagent. With certain solvent systems, the constituents of perspiration also spoil the chromatogram by appearing as unknown extra zones. 

Derivatization reagent Anisaldehyde-sulfuric acid VaniUin-snlfu ric add Vanillin-sulfuric VanilUn-sulfuric add (Autosprayer) add ... 

Derivatization reagent Anisaldehyde-sulfuric acid Anisaldehyde-sulfuric add Vanillin-sulfuric acid Vanillin-sulfuric acid... 

Information on the derivatization can be in the form of either reagent names (e.g. Dragendorff , vanillin-sulfuric acid ) or a hterature reference (e.g. JFFW la/265 indicates the reagent in the Jork/Funk/Fischer/Wimmer Vol. la, p. 265 2,5-dimethoxytetrahydrofuran-4-(dimethylamino)-benzaldehyde reagent). 

Figure 49. Identification of primrose root dry extract (DE) using two TLC systems after derivatization with vanillin-sulfuric acid reagent (shots taken in white light)...

Highly nonpolar compounds such as fatty acids, glycerides, alkanes, and some lower terpenoids require simple nonpolar solvent systems (e.g., cyclohexane, hexane, pentane, diethyl ether.hexane mixtures) and may be difficult to detect by UV (i.e., no chromophore) or by spray detection (use charring reagents, e.g., vanillin-sulfuric acid). 

Some of the innumerable reagents used in TEC are based on reactions with more or less well-established mechanism. Eor example, sodium iodobismuthate (Dragendorff reagent) is widely used among others for alkaloids and quaternary ammonium compounds, 4-dimethylaminobenzaldehyde for primary amines and amino acids, 2,4-dinitrophenylhydrazine for aldehydes and ketones, ninhydrin for amino acids and some antibiotics, fluorescamine for primary and secondary amines, phosphomolybdic acid for lipids, various steroids, and other compounds, chlorine vapor followed by Kl/starch for amines and amides. More complex is the mechanism of the reactions with some other reagents, containing high concentrations of sulfuric acid, vanillin/sulfuric acid, phosphoric acid, aluminum chloride, antimony(III)... 

If destructive reagents (e.g., vanillin-sulfuric acid) are necessary for detection of the separated compounds, a vertical channel must be scraped in the layer about half a centimeter from the edge of the streak. After covering the major portion of the layer with a suitable glass plate, the part of the... 

Reagent 1 A solution of 1 g vanillin in 70 ml ethanol (96%) was treated cautiously with 10 ml cone, sulfuric acid. 

Another method to make compounds visible, almost universally used, consists of heating the plate after spraying it with sulfuric acid which leaves charred blots behind. This approach is, however, not adapted to quantitative TLC in this case, development is effected by immersion of the plate, using a general (phosphomolybdic acid, vanillin), or specific (e.g. ninhydrin in alcoholic solution for amino acids) reagent. Hundreds of reagents have been described that serve to introduce chromophores or fluorophores groups into the analytes molecules after separation. 

Uses Curing accelerator for unsat. polyester resins extraction solvent in sulfur dioxide refining dyes intermediates mfg. of vanillin stabilizer (acid acceptor) acylation reagent intermediate for paints accelerator in food-contact crosslinked polyesters Regulatory FDA 21CFR 177.2420... 

Uses Curing accelerator for unsat. polyester resins extraction solvent in sulfur dioxide refining dyes intermediates mfg. of vanillin stabilizer (acid acceptor) acylation reagent intermediate for paints accelerator in food-contact crosslinked polyesters Regulatory FDA 21CFR 177.2420 HAP Manuf./Distrib. Aarti Ind. Ltd http //www.aartigroup.com-, Aceto http //www.aceto.com, Aldrich http //www.sigma-aldrich.com-, Allchem Ind. http //www.aiichem.com, BASF AG http //WWW. basf. de... 

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