Thin-layer fluorometry

By the total internal reflection condition at the liquid-liquid interface, one can observe interfacial reaction in the evanescent layer, a very thin layer of a ca. 100 nm thickness. Fluorometry is an effective method for a sensitive detection of interfacial species and their dynamics [10]. Time-resolved laser spectrofluorometry is a powerful tool for the elucidation of rapid dynamic phenomena at the interface [11]. Time-resolved total reflection fluorometry can be used for the evaluation of rotational relaxation time and the viscosity of the interface [12]. Laser excitation can produce excited states of adsorbed compound. Thus, the triplet-triplet absorption of interfacial species was observed at the interface [13]. 

Boto and Bunt [465] used thin-layer chromatography for the preliminary separation of chlorophylls and phaeophytins from seawater, and combined this with selective excitation fluorometry for the determination of the separated chlorophylls a, b, and c, and their corresponding phaeophytin components. An advantage of the latter technique is that appropriate selection of excitation and emission wavelengths reduces the overlap among the emission spectra of the various pigments to a greater extent than is possible with broadband excitation and the use of relatively broadband filters for emission. 

Dunn and Stich [78] and Dunn [79] have described a monitoring procedure for polyaromatic hydrocarbons, particularly benzo[a]pyrene in marine sediments. The procedures involve extraction and purification of hydrocarbon fractions from the sediments and determination of compounds by thin layer chromatography and fluorometry, or gas chromatography. In this procedure, the sediment was refluxed with ethanolic potassium hydroxide, then filtered and the filtrate extracted with isooctane. The isooctane extract was cleaned up on a florisil column, then the polyaromatic hydrocarbons were extracted from the isoactive extract with pure dimethyl sulphoxide. The latter phase was contacted with water, then extracted with isooctane to recover polyaromatic hydrocarbons. The overall recovery of polyaromatic hydrocarbons in this extract by fluorescence spectroscopy was 50-70%. 

Sawicki, E., T. W. Stanley, S. McPherson, and M. Morgan. Use of gas-liquid and thin-layer chromatography in characterising air pollutants by fluorometry. Talanta 13 619-629, 1966. 

In thin-layer chromatographic methods, sulfonamide residues were first separated on commercially available silica gel plates using various solvent mixtures as mobile phase, and subsequently detected by fluorometry after spraying... 

Shoaf and Lium [103] used thin layer chromatography to separate algal chlorophylls from their degradation products. Chlorophyll is extracted from the algae with dimethyl sulphide and chromatographed on commercially available thin layer cellulose sheets, using 2% methanol and 98% petroleum ether as solvents, before determination by either spectrophotometry or fluorometry. 

Quantitative Thin-Layer Chromatography of Pesticides by In Situ Fluorometry... 

No doubt as a result of the continuing widespread use of alkaloid-containing drugs, new and sensitive analytical methods for their identification have been developed. For example, amphetamines and phenethylamines in blood and urine have been determined by gas chromatography as their corresponding acetamide derivatives5 or directly by combination of fluorometry, gas-liquid and thin-layer chromatographies.6 The latter technique may also be used independently for this purpose.7,8... 

Thin-Layer Chromatography Coupled with Fluorometry. Aliquots of the prepared samples stored in the pear-shaped flasks are spotted on the thin-layer plates. The development of these plates for separation of the individual compounds can be done in one or two directions which takes place in an equilibrated chamber first with a mixture of toluene/n-hexane/n-pentane (5 90 5) to a distance of 15-16 cm. After drying, the plates are developed in the second direction with a mixture of methanol/diethyl ether/water (6 4 1). A typical two dimensional TLC of a PAH standard is shown in Figure 3. 

Winkler, B. C., W. J. Dunlap, L. M. Rohrbaugh, and S. H. Wender A thin-layer chromatograpghy-fluorometry method for quantitative analysis of scopoline and scopoletine in tobacco. J. Chromatog. 36, 670 (1968). 

Quantitative Determination of Clob-azam in Serum and Urine by Gas Chromatography, Thin-Layer Chromatography Fluorometry J. Clin. Chem. Clin. Biochem. 18(4) 209-214 (1980) CA 93 18816a... 

Routine Identification of Drugs of Abuse in Human Urine. I. Application of Fluorometry, Thin-Layer and Gas-Liquid Ghromatography J. Chromatogr. 55(2) 255-266 (1971)... 

Pataki, G., and Niederwieser, A. (1967). Thin-layer chromatography of nucleic acid bases, nucleosides, nucleotides and related compounds. IV. Separation on PEI-cellulose layers using gradient elution and direct fluorometry of spots. J. Chromatogr. 29 133-141. 

Pataki, G. (1968). Some recent advances in thin layer chromatography. II. Application of direct spectrophotometry and direct fluorometry in amino acid, peptide, and nucleic acid chemistry. Chromatographia 1 492-503. 

Dal Cortivo, L.A., Dihrberg, A. and Newman, B. (1966) Identification and estimation of lysergic acid diethylamide by thin layer chromatography and fluorometry. Anal. Chem., 38,1959-1960. 

Niwaguchi, T. and Inoue, T. (1971) Studies on quantitative in situ fluorometry of lysergic acid diethylamide (LSD) on thin-layer chromatograms. /. Chromatogr., 59, 127-133. 

Mule, S.J. (1971) Routine identification of drugs of abuse in human urine. I. Application of fluorometry, thin-layer and gas-Uquid chromatography. Journal of Chromatography, 55,255-266. 

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