Reactions for Detection

Non-destructive detection, so important for preparative TLC, can be achieved by using known fluorescent adsorbents the fluorescence is quenched by UV-absorbing substances. The regular use of such adsorbents is recommended. Convenient fluorescent properties can be imparted to the layer after TLC, e. g., by spraying with morin [32] (No. 169), 2, 7 -dibromo- or 2, 7 -dichlorofluorescein [43, 127] (No. 63), various dyes [193] or an optical bleach like UVITEX [131] (Nos. 258,259). Visualisation with iodine is very useful [1, 12, 122, 125, 218] (No. 141), yielding unstable coloured addition products. The zones of hpophilic substances in preparative TLC can be rendered visible also by means of a fine spray of water [10, 69]. 

Any reagent used in steroid PC can be employed on cellulose layers some are given in Tables 58 and 59. Neher [129] gives detailed documentation about application and specificity. 

See also the systematic investigations of Lisboa [215, 216] on the application of some of these colour reactions to different groups of steroids. 

For completeness, the following reagents may be quoted, although they are not specific and are less important permanganate-sulphuric acid (No. 200), dichromate-sulphuric acid [70], ferric chloride for bile 

C) 16 % in butanol B) 6% in acetic anhydride E) 50% in acetic acid 242 Sulphuric acid-hypochlorite 46 Chlorosulphonio acid-acetic acid 

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The reaction between olefins and ozone produces light that can be measured and related to the concentration of the reactants. One of the preferred methods for measuring ambient ozone concentrations utilizes the chemiluminescence generated in the ozone-ethylene reaction for detection. Recently, Hills and Zimmerman (16) described the use of this detection principle for determining hydrocarbon concentrations. They utilized the chemiluminescence created when ozone reacts with isoprene for development of a continuous, fast-response isoprene analyzer. This real-time isoprene system is reported to be linear over three orders of magnitude and to have a detection limit of about 1 ppbv. Because the system doesn t include a preseparation of hydrocarbons, interferences from other olefins (ethylene, propylene, and so forth) could occur. Thus far the chemiluminescent detector has been used to monitor isoprene emissions under conditions in which the concentrations of olefins that could interfere are negligible compared to those of the biogenic hydrocarbon. 

Refs l)J.Tafel, Ber 25, 4l2-13(1892)(Color reaction for detection of Centr 1 rose-red color is produced when a few crysts of K2Cr207 are added to a small sample dissolved in coned H2S04) 2)H.Lecorche P. Jovinet, MP 23, 69-78(I928)(A rather complicated and tedious method of quantitative detn of Centr 1 when in mixts with NG) 3)J.Goujon, MAF 8, 837-902(1929)... 

Color reactions of Centr 2 with HzSe03-H2S04 solns) 2)Kast-Metz(1944), l67(Color reactions for detection of Centr 2 are identical with those described for Centr 1) 3)Kast-Metz(1944), 292-3 (Gravimetric and volumetric methods for detn of Centr 2 in proplnts are similar to those for Centr 1) 4)T.C.J.Ovenston, Analyst 74, 344-51(1949)... 

Stefanic, S., Shaikenov, B.S., Deplazes, P., Dinkel, A., Torgerson, P.R. and Mathis, A. (2004) Polymerase chain reaction for detection of patent infections of Echinococcus granulosus ( sheep strain ) in naturally infected dogs. Parasitology Research 92, 347-351. 

Sims PW, Vasser M, Wong WL, Williams PM, Meng YG. Immunopolymerase chain reaction using real-time polymerase chain reaction for detection. Anal Biochem 2000 281(2) 230-232. 

Itoh F, Suzuki A, Hinoda Y, Imai K. Double determinant immuno-polymerase chain reaction for detecting soluble intercellular adhesion molecule-1. Artif Organs 1996 20(8) 898—901. 

Nitration with pernitrous acid. The first investigations into the nitration of benzene with per-nitrous acid were performed by Trifonov [166], In 1922 he found o- nitrophenol to be the reaction product and suggested the application of the reaction for detecting benzene and other aromatic hydrocarbons. His results were confirmed by the experiments of Halfpenny and P. L. Robinson [170],... 

III) Allele specific hybridisation (Figure 2) Fragments amplified in an allele unspecific PCR are measured with allele specific probes (Molecular Beacons, TaqMan probes or Scorpion), which can either be used in a single PCR or in multiplex reactions for detection of both alleles in one reaction [13]. This method has minor background problems, however the dynamic range may be limited due to competition of the probes. The Molecular Beacon proach has been developed for B. graminis and M. fijiensis [13]. 

G., Lelie, P.N. Reliability of polymerase chain reaction for detection of hepatitis C virus. Lancet 1993 341 722-724... 

The chemical structures of eight typical biotic dicarboxylic acids are shown in Fig. 1. They are extremely hydrophilic and require a specific reaction for detection using the color-producing reagent such as 2-nitrophenylhydra-zine hydrochloride. 

Zoh GJ, Melchers WJ, Kopecka H, Jambroes G, van der Poel HJ, Galaraa JM. General primer-mediated polymerase chain reaction for detection of enteroviruses application for diagnostic routine and persistent infections. J Clm Microbiol 1999 30 60-5. 

L. Ilojmami seiii from Jamaica the following letter to the editors of the journal Annalcn dcr Chcmic und Pharmazie regarding a new reaction for detecting phosphorus in cases of poisoning ... 

Rahn K, Wilson JB, McFadden KA, Read SC, Elhs AG, Renwick SA, Clarke RC, Johnson RP (1996) Comparison of Vero ceU assay and PCR as indicators of the presence of verocytotoxigenic Escherichia coli in bovine and human fecal samples. Appl Environ Microbiol 62 4314 317 Read SC, Clarke RC, Martin A, De Grandis SA, Hii J, McEwen S, Gyles CL (1992) Polymerase chain reaction for detection of verocytotoxigenic Escherichia coli isolated from animal and food sources. Mol Cell Probes 6 153-161... 

Jl. Jensen, J. S., Uldum, S. A., Sonderg ard-Andersen, J., Vuust, J., and Lind, K., Polymerase chain reaction for detection of Mycoplasma genilalium in clinical samples. J. Clin. Micro-biol.29, 46-50 (1991). 

S10. Sjobring, J., Mecklenburg, M., Andersen, A. B., and Miomer, H., Polymerase chain reaction for detection of Mycobacterium tuberculosis. J. Clin. Microbiol. 28, 2200-2204 (1990). 

Sakakura, C., Hagiwara, A., Shirasu, M., Yasuoka, R., Fujita, Y., Nakanishi, M., etal, Polymerase chain reaction for detection of carcinoembryonic antigen-expressing tumor cells on milky spots of the greater omentum in gastric cancer patients A pilot study. Int. 

Buzaid, A.C., Balch, C.M. (1996) Polymerase chain reaction for detection of melanoma in peripheral blood too early to accesses clinical value. / Nat Cancer Inst, 88, 569-570. 

Derivatization reactions for detection are usually carried out postchromatography, and many hundreds of reagents have been reported in the literamre. Selected examples are listed in Table 1. 

Application of iodine-azide reaction for detection of amino acids in thin-layer chromatography. J. Chromatogr. A, 2004, 1059, 171-174. 

Up to the end of 1965, over 500 publications had appeared on the TLC of vitamins and related compounds. About 80% of these concerned the fat-soluble class. Five surveys have been made [8, 70, 77, 110, 130]. Methods of proved value and also hitherto unpubhshed experience is described here, based on this mass of work. Many additional systems and reactions for detection will certainly be still found, which will help in solving specific problems... 

Adenine may be detected specifically on silica gel and cellulose by using the Dragendorff-reagent (No. 98). All the reactions for detection of pentoses in nucleosides are useful for identifying these compounds on thin-layer chromatograms. 

We include some observations of the visual sensitivities of reactions for detecting species of interest. These are usually based on a few mL of solution in a test tube or small beaker. 

The disadvantages listed in Table 10.2 are either alleviated or greatly diminished by the use of the waveform in Table 10.3. Here, the electrode current is integrated electronically throughout a rapid cyclic scan of the detection potential (Edet) within the pulsed waveform. The potmtial scan proceeds into (positive scan) and backs out of (negative scan) the region of the oxide-catalyzed reaction for detection by Mode II. 

Reactions for detection and identification of aromatic hydrocarbons can be divided into substitution reactions (nitration, chlorosulfonation, acetylation), addition reactions (7r-complexes), and oxidative reactions (oxidation of aliphatic chains, oxidation of aromatic hydrocarbons to quinones). The... 

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