Thin layer chromatography 2-dimensional

The total phosphoms content of the sample is determined by method AOCS Ja 5-55. Analysis of phosphoUpid in lecithin concentrates (AOCS Ja 7-86) is performed by fractionation with two-dimensional thin-layer chromatography (tic) followed by acid digestion and reaction with molybdate to measure total phosphorous for each fraction at 310 nm. It is a semiquantitative method for PC, PE, PI, PA, LPC, and LPE. Method AOCS Ja 7b-91 is for the direct deterrnination of single phosphoHpids PE, PA, PI, PC in lecithin by high performance Hquid chromatography (hplc). The method is appHcable to oil-containing lecithins, deoiled lecithins, lecithin fractions, but not appHcable to lyso-PC and lyso-PE. 

One-dimensional thin-layer chromatography. This method, based on the work of Wolf and McPherson, will determine more than 0.1% terminal 8-sultones in the neutral oil. This implies that if the AOS contains 1% neutral oil, greater than 30 ppm (active matter basis) of terminal 5-sultones can be determined. Some samples contain a compound having an R( of approximately 0.03 U less than the 5-sultones. This should not be reported as terminal 8-sultones. C14 and C16 terminal 8-sultones have the same retention (R 0.35-0.55, depending on the humidity) and therefore appear as one spot. 

Two-dimensional thin-layer chromatography. This method is used to verify the presence of terminal 5-sultones, terminal unsaturated y-sultone, and terminal 2-chloro-y-sultone, if they are detected in the gas chromatographic determination. After extraction of the neutral oil from the AOS sample, the neutral oil is made up volumetrically to at least a 10% solution in hexane. Of this solution 3 pi is spotted onto a silica gel TLC plate together with standard sultones. It is twice developed with 2-propyl ether and then after turning the plate 90° twice developed with 60/40 n-butyl chloride/methylene chloride. The... 

Paper chromatography (PC) and thin layer chromatography (TLC) have been used since the 1940s. Preparative PC on Whatman 3 paper, analytical PC on Whatman 1 paper, and analytical TLC on microcrystalline cellulose, silica gel, or polyamide have been applied with a variety of solvents and the behaviors of anthocyanins have been similar in all media. Two-dimensional TLC allows the separation of several compounds and has been nsed to clarify the anthocyanin compositions of different commodities. ... 

Successive separation steps, e.g. in two-dimensional chromatography (two-dimensional thin-layer chromatography) that result in three-dimensional signal functions y = f(ziyz2)y as schematically shown in Fig. 3.4(v). 

The theoretical work that exploited the advantages of the multidimensional separation format appears to have been developed much later than the original experimental work. One of the earliest studies was conducted by Connors (1974), who assumed that the distribution of spots on a two-dimensional thin-layer chromatography (2DTLC) plate could be modeled using a Poisson distribution of data on each retention axis. He then constructed equations that related the number of chromatographic systems needed to resolve a specific number of compounds. One... 

Guiochon, G., Gonnord, M.F., Siouffi, A., Zakaria, M. (1982). Study of the performances of thin-layer chromatography. VII. Spot capacity in two-dimensional thin-layer chromatography. J. Chromatogr. 250, 1. 

Rezanka, T. (1996). Two-dimensional separation of fatty acids by thin-layer chromatography on urea and silver nitrate silica gel plates. J. Chromatogr. A 727(1), 147-152. 

This effect is illustrated in Fig. 17.1. Multidimensional chromatography separations can be done in planar systems or coupled-column systems. Examples of planar systems include two-dimensional thin-layer chromatography (TLC) (Consden et al., 1944 Grinberg et al., 1990), where successive one-dimensional TLC experiments are performed at 90° angles with different solvents, and 2D electrophoresis, where gel electrophoresis is run in the first dimension followed by isoelectric focusing in the second dimension (O Farrell, 1975 Anderson et al., 1981 Celis and... 

Two-dimensional thin-layer chromatography (TLC) with adsorbent gradient has allowed the separation of quinolizidine alkaloids in the herb and in several alkaloids from Genista sp. <2004MI89>. 

The difference between this technique and GC or HPLC is that the separation process occurs on a flat essentially two-dimensional surface. The separated components are not usually eluted from the surface but are examined in situ. Alternatively, they can be removed mechanically for further analysis. In thin-layer chromatography (TLC), the stationary phase is usually a polar solid such as silica gel or alumina which is coated onto a sheet of glass, plastic, or aluminium. Although some moisture is retained by the stationary phase, the separation process is predominantly one of surface adsorption. Thin layers are sometimes made from ion-exchange or gelpermeation materials. In these cases the sorption process would be ion-exchange or exclusion. 

SPE, chromatography (i.e., thin-layer chromatography, gel-permeation chromatography and HPLC) and on-line multi-dimensional chromatography. These techniques are rarely used in routine tablet assays due to their technical difficnlties, labor intensity and problems with recovery. 

The toxins are easily detected, after separation of the compounds from plasma and renal tissue on silica thin layers, by their fluorescence in UV light orellanine is visible as navy blue, orellinine as dark blue, and orelline as light blue (Horn et al., 1997). Beside thin-layer chromatography (TLQ, use of HPLC for the analysis of orellanine, e.g., in mushroom extracts, has also been reported. Quantitative analysis of orellanine in plasma samples, or in (rat) urine samples, was performed by extraction of orellanine on XAD-4 resin, two-dimensional TLC on cellulose, and spectrophotometric evaluation of the orelline produced on the TLC plates after UV-induced decomposition of the orellanine. 

TLC. Aliquots of samples and standards were run on silica-coated thin layer chromatography (TLC) plates in either n-butanol/acetic acid/water (4 1 1 by vol. (BUOH/HAC/H2O)) or n-propanol/concentrated ammo-nia/water (8 1 11, pre-equilibration). These eluents were previously described (Keller et ah, 1984) for the two-dimensional TLC-separation of elastin cross-links. 

Special attention was given to the characterization of the radioactive metabolites found in the strawberry fruits where no parent compound was detectable. Unidentified, very polar metabolites accounted for 83% of the material while 3% was identified as thiazolidine-2-thione-4-carboxylic acid by two-dimensional thin-layer chromatography. Treatment with diazomethane allowed for GC-MS confirmation of the latter as the methylated derivatives of the thiazolidine. 

Two-dimensional, thin-layer chromatography can also be used for... 

Tentative confirmation of suspected liquid chromatographic peaks has been achieved in the analysis of carazolol and seven sedatives in swine kidney, by using photodiode-array detection in the wavelengUi range of 220-320 nm. It was reported (526) that further identification could be made possible if the corresponding fractions of the eluate were submitted off-line to two-dimensional thin-layer chromatography. 

Speccropho tome trie detn of HNDPhA in micro gram quantities) 7) S.K. Yasuda, Explosivst 1963 ( 2), 34- 38 CA 60, 14325(1964) (Identification N Nitroso N-Nitrodiphenylamines by two-dimensional thin-layer chromatography)... 

P Gimsing, E Nexo, E Hippe. Determination of cobalamins in biological material. II. The cobalamins in human plasma and erythrocytes after desalting on nonpolar adsorbent material, and separation by one-dimensional thin-layer chromatography. Anal Biochem 129 296-304, 1983. 

Friedberg and Hayden (15) reported that glutamic acid was formed when poly-L-proline was irradiated in dilute aqueous solution in the absence of 02. We also found glutamic acid formation (G = 0.14) under similar conditions and confirmed the identity of the glutamic acid by two-dimensional thin-layer chromatography. A possible intermediate in this reaction... 

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