Polyamides thin layer chromatography

In this equation, 8 is a differential parameter developed from Sephadex and polyamide thin-layer chromatography, and ARm(3) and ARm(6) are the values for the substituents at the 3 and 6 positions, respectively. The number of compounds is sufficiently large so that the correlation could be accepted statistically. Although Equation 31 can be used to predict... 

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. ... 

Although the interest in, and application of layer chromatography has historically resulted from the development of PC, it was soon replaced by thin-layer chromatography (TLC). In PC, only one stationary phase matrix is available (cellulose), at variance to TLC (silica, polyamide, ion-exchange resins, cellulose). Using a silica-gel plate, separation of a sample can be accomplished in approximately 1 h as compared with many hours on paper. The plate size is much smaller than the necessary paper size. Also, more samples can be spotted... 

Salicylic acid and Its metabolite were separated by two methods. The first was thin layer chromatography on cellulose with BAW solvent as for the In vivo metabolism studies. A quicker separation was achieved with a polyamide column. The entire 400 pL from an individual assay was placed on top of a 0.8 x 2.0 cm column packed with Polyamide-6 (Accurate Chemical and Scientific Corp.). The salicylic acid metabolite was eluted with 6 mL water but salicylic acid was retained. 3a70B scintillation fluid (Research Product International Corp.) was used to determine the radioactive content of the entire 6 mL of eluant. Separation of salicylic acid and its metabolite by polyamide column chromatography was verified by thin layer chromatography. 

In earlier times, thin-layer chromatography (TLC), polyamide chromatography, and paper electrophoresis were the major separation techniques for phenolics. Of these methods, TLC is still the workhorse of flavonoid analysis. It is used as a rapid, simple, and versatile method for following polyphenolics in plant extracts and in fractionation work. However, the majority of published work now refers to qualitative and quantitative applications of high-performance liquid chromatography (HPLC) for analysis. Llavonoids can be separated. 

Thin-layer chromatography of dansyl-amino acids on a polyamide plate. A After solvents 1 (1.5% formic acid) and 2 (toluene-acetic acid). B After solvents 1,2, and 3 (ethyl acetate-methanol-acetic acid). See text for further details. 

One of the older methods used to detect the presence of preservatives in soft drinks and juices is thin-layer chromatography (Woidich el al., 1967). This provides a useful method to detect benzoic and sorbic acids as well as the substituted benzoic acids. The first stage involves the extraction of the preservatives with diethyl ether prior to their chromatographic separation on polyamide plates. Although it is difficult to use this procedure to quantify the level of these preservatives in a sample, it is not impossible. This approach can still be used today by a laboratory that does not have access to HPLC. 

For emulsion tests, polyamide-coated terephthalate plastic plates are attached powder-side down by double-faced transparent tape strips to the undersurface of the lid of 9 x 1 cm Pyrex Petri dishes. The plates, 2x3 cm, are cut from standard 20 x 20 cm polyamide-terephthalate plates used for thin-layer chromatography. They are Polygram - Polyamide-6 UV254, procured from Macherey-Nagel and Co. through Brinkmann Instruments, Inc., Westbury, N.Y. As indicated, they contain a fluorophore (zinc silicate) activated by short-wave UV, but not active in the 360-nm range used herein. 

Peak from Sephadex LH-20 column chromatography (see Fig. 4.6) Polyamide thin-layer chromatographic method (3-dimensional) Silica gel thin-layer chromatographic method0 (one-dimensional )... 

CD s dissolved in the mobile phase solutions have been used in thin-layer chromatography with polyamide stationary phase (29,30) and 2) CD complexation equilibria of ionic compounds were studied by a chromatographic method using an ion exchanger as stationary phase and mobile phase solutions containing CD s in various concentrations (31). 

Thin-layer chromatography on alumina,271 silica gel,139,271>272 cellulose,262,272 Avicel,250,262 and polyamide273 thin layers has extended considerably the applications of chromatography to the separation and purification of imidazoles. Polyamide layers are useful especially for the separation of imidazoles and their 1-methyl derivatives and (using methyl ethyl ketone as solvent) allows separation of the more polar co mpounds su ch as 1,3 -dimethylimidazolium iodide.2 7 3 Imidazolines have also been separated by thin-layer chromatography.274... 

Benzoic acid derivatives often contain amino, hydroxy, carboxy, and nitro groups. Analysis of substimted benzoic acids by thin layer chromatography was performed on silica gel, polyamide, and cellulose containing UF254 fluorescent indicator. For the mobile phase, different mixtures were used hexane-acetic acid hexane-ethyl acetate-formic acid chloroform-methanol-phosphoric acid cyclohexane-acetic acid benzene-ethanol etc. Because benzoic acid derivatives have similar retention parameters, their separation requires a thorough optimization of conditions (the nature of the stationary phase, the composition of the mobile phase, and the pH of the solutions). 

Polyamide (polycaprolactam) has been introduced only recently. It has been used almost exclusively for separations of phenolic compounds by thin-layer chromatography [e.g., Refs. (5,7J-75)], but aromatic nitro... 

Sephadex thin layer chromatography and bioautography were combined for the identification of antibioticsIdentity tests for antibiotics sensitivity discs were developed. Several thin layer chromatography methods for identification of penicillin are reportedl58-152, A simple and rapid polyamide chromatography of penicillins is described S. (See Section 6.2.4 for additional systems). 

Kulbe, K. Rapid separation of phenylthiohydantoin (PTH) amino acids by thin-layer chromatography on polyamide glass plates. Anal. Biochem. 1971, 44, 548-558. 

Endres, H. (1969). Polyamides as adsorbents. In Thin Layer Chromatography. A Laboratory Handbook, 2nd ed., E. Stahl (Ed.). Springer-Verlag, New York. pp. 41-... 

Wang, K.-T., and Weinstein, B. (1972). Thin layer chromatography on polyamide layers. 

Mustafa et al. (1992) used two-dimensional thin-layer chromatography on polyamide sheets to identify PTH-amino acids that have similar values. The solvent systems used in this study were particularly effective for the separation of PTH-amino acids and provided a clear separation of all the PTH-amino acids studied with the exception of isoleucine/leucine. 

Synthesis of DNP-N3 and [ H]DNP-N3. DNP-N3 and [ H]DNP-N3 are synthesized by direct displacement of fluorine in l-fluoro-2,4-dinitrobenzene or the 3,5, 6- H analogs. Fluorodinitrobenzene (14.7 mg) is dissolved in 0.25 ml of redistilled dimethylformamide. Solid sodium azide 10 mg, is added, and the mixture is stirred in the dark at 20° for 2 hr, then dried under reduced pressure. The dried film is dissolved in a minimal volume of dioxane and streaked onto thin-layer chromatography (TLC) polyamide plates (Chen-Ching Trading Co., Ltd., Taiwan). The... 

The analysis consisted of three stages, beginning with SPE of the dyes from pills, using a polyamide solid phase. Thin-layer chromatography was utiliz to screen the dyes via two solvent systems and solid supports (silica gel and cellulose), followed by confirmation by CE coupled to a diode array detector. The authors reported that the 14 dyes could be unambiguously identified with these parameters. 

Another organic sorption material for thin-layer chromatography is polyamide. In contrast to celluloses, polyamides are synthetic organic resins. Two types of polyamides are used polyamide 6 and polyamide 11. Polyamide 6 consists of a polymeric caprolactam, while polyamide 11 is a polyundecanamide. Polyamides are synthesized as coarse granulates. To get a particle size distribution suitable for thin-layer chromatography two different techniques are applied ... 

Both types of polyamides for thin-layer chromatography are available as bulk materials and as precoated layers on different carriers (plates, foils). The particle sizes are in the same ranges as used for other sorbents. Polyamides are applied for the separation of polarcompounds, which are able— because of their molecular structure—to interact with the amide group via hydrogen bonding. This is the reason why substance groups such as amino acids and derivatives (95,97), carboxylic acids (98), phenolic compounds (99-101), and preservatives (102) can be separated on polyamide as stationary phase. 

Instruments which can be used for recording UVA IS spectra are discussed in Chapter 5, Instrumental Thin Layer Chromatography (see there Fig. 11). The wavelengths usually correspond to the spectra of the same substances in solution. But adsorbents, with, e.g., silanol, amino or, polyamide groups, and solvent traces or pH differences, can cause either bathochromic or hypsochromic shifts. Nevertheless, these absorption spectra can ease characterization, particularly when authentic reference substances are chromatographed on the same TLC plate. 

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