Ninhydrin vapor reagent

Note The TDM reagent can be used everywhere, where o-tolidine is employed. It can also be used on chromatograms, that have already been treated with ninhydrin, Pauly or ammonia perchlorate reagent or with iodine vapor [1]. Water may be used in place of 80% 2-propanol when making up solutions II, III and IV. The chlorine gas atmosphere in the chromatography chamber can also be created by pouring 5 ml hydrochloric acid (ca. 20%) onto 0.5 g potassium permanganate in a beaker such a chlorine chamber is ready for use after 2 min. 

The ninhydrin test will not interfere with the Ehrlich reagent. Therefore, a plate can be examined under UV light, immersed in iodine vapors, treated with ninhydrin, and the Pauly or Ehrlich reagents successively. 

Silica gel 60G-coated plates can be used with thin-layer chromatography, and a suitable solvent system is butanol-acetic-water (6 2 2, v/v). If the product is pure sphingosine-l-P, it should migrate with an Rf value of 0.48. It will give a positive reaction to the phosphorus and ninhydrin reagents, as well as exhibiting a positive reaction to iodine vapors. 

Cephalosporines are derived from natural cephalosporin C produced by Cephalosporinum acre-monium. They possess a cephem nucleus (7-amino-cephalosporanic acid) substituted with two side chains. They are commonly divided into three classes differing in their spectra and toxicity. Cephalosporines can be analyzed both by normal and reversed-phase TLC or HPTLC hence, more efficient separation is obtained on sUanized gel than on bare, untreated silica gel. Mobile phases are polar and similar to those used for penicillins. Acetic add or acetates are very often components of solvents for normal phase (NP) TLC, the ammonium acetate-acetic acid buffer for RP TLC. All cephalosporines can be detected at 254 nm. The detection limit can be diminished by applying reagents such as ninhydrin, iodoplatinate, chloroplatinic acid, or iodine vapor. Alternative to UV detection is bioautography with, for instance. Neisseria catarrhalis. 

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)... 

Preliminary identification of many lipids may be obtained by the use of specific sprays on tic plates. Reagents such as 2, 7 -dichlorofluorescein and rhodamine 6G permit the nondestructive revelation of lipid bands and, if sufficient lipid is present, a water spray can also be used. Exposure to iodine vapor can be employed provided fatty acid analysis is not required. More specific chemicals include ninhydrin, Schiff-periodate, and Zinzadze s reagent (cf. Kates, 1972 Stahl, 1969). 

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