Thin layer chromatography - ultraviolet

Such AOAC method is a satisfactory method but is thought not to be in current use for various reasons thin-layer chromatography argentation thin-layer chromatography ultraviolet (detector)... 

Thin-layer Chromatography-Ultraviolet Spectrophotometry. In plasma, urine or faeces diazoxide and metabolites— A. W. Pmiii et al., J. Pharmac. exp. Ther., 1974,188, 248-256. 

Quantification. Thin-layer Chromatography-Ultraviolet Spectrophotometry. In blood or urine—E. Bertol et al, J. pharm. biomed. Analysis, 1983,1, 373-377. 

Thin-layer Chromatography-Ultraviolet Spectrophotometry. In plasma, serum or urine sensitivity 500ng/ml in serum—R. L. Galeazzi etal., J. Pharmacokinet. Biopharm., 1979, 7, 453-462. 

High Performance Liquid Chromatography Electrophoresis Thin Layer Chromatography Ultraviolet and Visible Spectroscopy Fluorescence and Phosphorescence Atomic Absorption and Plasma Spectroscopy X-ray Methods Mass Spectrometry... 

Aranda, M., Morlock, G. (2010) Quantification of pyri-tinol in sohd pharmaceutical formulation by high-performance thin-layer chromatography-ultraviolet detection and selectivity evaluation by mass spectrometry. Journal of Liquid Chromatography Related Technologies, 33, 957-971. 

Tetrahydrofuran Thin layer chromatography Ultraviolet spectra Valerophenone synthase... 

The infrared spectra of a set of 2-thiazolylthioureas are reported in Ref. 486. The ultraviolet spectra of l-aryl-3-(2-thiazolyl)thioureas are characterized by two bands of approximate equal intensity around 282 and 332 nm (492). For l-alkyl-3-(2-thiazolyl)thioureas these bands are shifted to 255 and 291 nm, respectively (492). The shape of the spectrum is modified further when l.l -dialkyl-3-(2-thiazolyl)thioureas are considered (491). Fragmentation patterns of various 2-thiazolylthioureas have been investigated (100, 493), some of which are shown in Scheme 158. Paper and thin-layer chromatography provide an effective tool for the analysis of these heterocyclic thioureas (494. 495). 

PLC is used for separations of 2 to 5 mg of sample on thin-layer chromatography (TLC) plates (0.25-nun layer thickness) or high-performance TLC (HPTLC) plates (0.1-mm thickness). In these instances, the method is termed micropreparative TLC. The isolation of one to five compounds in amounts ranging from 5 to 1000 mg is carried out on thicker layers. PLC is performed for isolation of compounds to be used in other tasks, i.e., further identification by various analytical methods, such as ultraviolet (UV) solution spectrometry [1] or gas chromatography/mass spectrometry (GC/MS) [2], obtaining analytical standards, or investigations of chemical or biological properties [3]. 

Two identification tests for oxytetracycline hydrochloride are given in the USP 28 [1], one being an ultraviolet absorption test and the other a color test. European Pharmacopoeia [2], British Pharmacopoeia (BP) 2003 [4], International Pharmacopoeia [5], and Pharmacopoeia of the People s Republic of China [6] described a thin-layer chromatography and color tests for identification of oxytetracycline hydrochloride and oxytetracycline dihydrate. For identification of oxytetracycline calcium, USP 28 [1] used Method II under identification of tetracycline <193>, whilst BP 2003 [4] described a TLC, color test, and calcium test as the method of identification. 

Dwivedi et al. used a thin-layer chromatographic densitometric and ultraviolet spectrophotometric methods for the simultaneous determination of primaquine and a new antimalarial agent, CDRI compound number 80/53 [68]. The new antimalari-al agent, compound 80/53 is unstable in acidic conditions where it is converted into primaquine. To conduct stability studies of this compound, thin-layer chromatography densitometric and ultraviolet spectrophotometric determination methods were developed. These methods are also suitable of the determination of compound 80/53 or primaquine in bulk and pharmaceutical dosage forms. 

Payne [30] carried out a field investigation of benzopyrene hydrolysate induction as monitor for marine petroleum pollution. Isaaq et al. [31] isolated stable mutagenic ultraviolet photodecomposition products of benzo(a)pyrene by thin-layer chromatography. 

Finally, and apart from the importance of micelles in the solubilization of chemical species, mention should also be made of their intervention in the displacement of equilibria and in the modification of kinetics of reactions, as well as in the alteration of physicochemical parameters of certain ions and molecules that affect electrochemical measurements, processes of visible-ultraviolet radiation, fluorescence and phosphorescence emission, flame emission, and plasma spectroscopy, or in processes of extraction, thin-layer chromatography, or high-performance liquid chromatography [2-4, 29-33],... 

Most of the reactions described in the following chapters were monitored by Thin Layer Chromatography (TLC) using plastic TLC plates coated with a thin layer of Merck 60 F254 silica gel. The products were detected by using an ultraviolet lamp or the TLC plates were treated with p-anisaldehyde reagent, prepared as explained below, and then heated to 120 °C to stain the spots. After visualization and measurement, the Rf values were recorded. 

The inclusion of a fluorescent dye into thin-layer plates can be used to detect substances that quench its fluorescence and so result in dark zones when the chromatogram is examined under ultraviolet radiation. Autoradiography can also be used in thin-layer chromatography and electrophoresis when samples are radio-labelled. 

The ultraviolet reflectance absorbance spectrum of a benzoic acid spot on a thin-layer chromatography place was recorded on a Shimadzu CS-930 TLC scanner, and is shown in Figure 5. The spectrum was obtained on a silica-gel F254 pre-coated TLC-plate (E. Merck) after elution with 7 2 2 acetone/ammonia 25 %/isopropanol. The absorbance maximum for this system was determined to be 225 nm. 

Thin layer chromatography (TLC) uses the same principles as GC or HPLC but is performed on a glass plate containing an adsorbent, such as silica or alumina, that attracts other molecules to its surface. A small portion of the sample to be analyzed is spotted on the plate. The plate is placed upright in a tank containing a small amount of solvent that then rises up the plate and separates the components of the sample. The separated components can be located with an ultraviolet lamp or by spraying the plate with chemicals to produce color. 

Cinnamyl anthranilate can be assayed by a method based on ester hydrolysis. Bulk samples of food-grade cinnamyl anthranilate have been analysed for purity by thin-layer chromatography and high-performance liquid chromatography. A method has been described for determining the content of this compound in food products by steam distillation followed by paper chromatography and examination under ultraviolet light it has a limit of detection of 1 pg (lARC, 1983). 

Increased porphyrins in clear fluid such as urine may be detected directly by their pink fluorescence if exposed to long ultraviolet (Fig. 7.3.2). The specificity of this screening assay may be improved if porphyrins are extracted by talcum [8]. These isolated porphyrins may be quantified using a spectrofluorimeter. As different porphyrias show specific excretion patterns, separation of the main porphyrins is desirable. The formerly used fractionated extraction enabled to separate the uroporphyrin fraction from the coproporphyrin fraction. In addition to uroporphyrin, the first fraction includes heptacarboxy- and part of hexacarboxyporphyrins, and in addition to coproporphyrin, the second fraction includes part of hexacarboxy- and pentacar-boxyporphyrins. Later on, thin-layer chromatography of methylester derivatives is used. 

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