Nondestructive with iodine

Nitrous fiunes reagent 225, 226 Nondestructive detection 42 ff -with fluorescent reagents 44 -with iodine 46 -with pH-indicator 45 Noradrenaline 76, 240, 393 — 396 Norephedrine 76 Norfenefnne 76 Norfenfluramine derivatives 45 1 l-Nor-d -THC-9-carboxy lie acid 289,292 Novonal 339 Nucleosides 364... 

Dichlorofluorescein. Prepare a 0.1% solution of 2, 7 -dichloro-fluorescein in 95% methanol. With a glass sprayer attached to a compressed-air line, spray the sheet that had first been treated with iodine with the dichlorofluorescein solution and then examine this sheet under short- and long-wave ultraviolet light. Lipids should appear as dark spots against a fluorescent background under both lamps. If the sheet is sprayed with dichlorofluorescein without the iodine pretreatment and then examined under short UV light, lipids will appear as yellow spots. Circle spots (open circles) with a pencil and compare the TLC results with previous observations from the iodine vapor detection study. The iodine and dichlorofluorescein techniques are both nondestructive. 

Thin-Layer Chromatography. Chiral stationary phases have been used less extensively in tic as in high performance liquid chromatography (hplc). This may, in large part, be due to lack of availability. The cost of many chiral selectors, as well as the accessibility and success of chiral additives, may have inhibited widespread commercialization. Usually, nondestructive visualization of the sample spots in tic is accomplished using iodine vapor, uv or fluorescence. However, the presence of the chiral selector in the stationary phase can mask the analyte and interfere with detection (43). 

Iodine vapor allows nonspecific, usually nondestructive detection of many sub-stances (e.g. surface active agents [129], pharmaceuticals [130, 131], polyethylene glycols [132], see also Table 12). In addition, reactions have also been described with the vapors of bromine [133—135], cyanogen bromide [136], chlorine [137-141, 209], ammonia [147-147] (see also the reagent Ammonia vapor ). 

Neither iodine nor 2, 7 -dichlorofluorescein is as sensitive as the PMA and H2SO4 spray procedures. Material not detected with these two nondestructive reagents will be detected using the destructive procedures. The sensitivity of lipid detec-... 

Detection techniques may be nondestructive or reversible, e.g., iodine or Rhodamine B, or destructive, e.g., sulfuric acid. Detection reagents are usually classified as general, i.e., those that react with a wide variety of different compound types, versus speciftc, i.e., reagents that indicate a particular compound or functional group. Some general reagents are destructive and others are not likewise, there are destructive and nondestructive specific chemical detection reagents. 

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