Thin layer chromatography spotting

G. Guiochon and A. M. Siouffi, Study of the performance of thin-layer chromatography. Spot capacity in thin-layer cltromatography , 7. Chromatogr. 245 1-20 (1982). 

Sequaris J.M.L., Koglin E., Direct analysis of high-performance thin-layer chromatography spots of nucleic purine derivatives by surface-enhanced raman-scattering spectrometry, Anal. Chem. 1987 59 525-527. 

Separation of amino acids and their identification in different mixtures are frequent tasks encountered in biochemistry. Thin layer chromatography is a fast, simple, and inexpensive approach to attain this goal. Because some of the components are UV-inactive, other methods, such as vibrational spectroscopy, should be applied for detection and identification. Comparative study based on Raman spectroscopy of thin layer chromatography spots of some weak Raman scatterers (essential amino acids) was carried out using four different visible and near-infrared laser radiation wavelengths 532, 633,785, and 1064 nm. The best results were obtained with simple silica gel plates. 

Istvan, K. Keresztury, G. Szep, A. Normal Raman and surface enhanced Raman spectroscopic experiments with thin layer chromatography spots of essential amino acids using different laser excitation sources. Spectrochim. Acta, Part A Mol. Biomol. Spectrosc. 2003, 59, 1709-1723. 

Chang,T., Lay, J.Q. Jr., Francel, R.J. (1984) Direct analysis of thin-layer chromatography spots by fast atom bombardment mass spectrometry. Analytical Chemistry, 56, 109-111. 

Chen, X. and Smart, R.B. 1992. Direct analysis of thin-layer chromatography spots by thermal extraction-gas chromatography-miass spectroscopy, J. Ghromatogr. Sci., 30 192-196. 

Polyvinyl chloride Aqueous extractants Barium, cadmium, lead and zinc organo-metallic stabilizers Thin-layer chromatography, spots located with aq. sodium rhodizoate [100]... 

Chang, T. T., J. 0. Lay, and J. F. Rudolph Direct Analysis of Thin-Layer Chromatography Spots by Fast Atom Bombardment Mass Spectrometry. Analyt. Chemistry 56, 109 (1984). 

Thin-Layer Chromatography. Chiral stationary phases have been used less extensively in tic as in high performance Hquid chromatography (hplc). This may, in large part, be due to lack of avakabiHty. The cost of many chiral selectors, as well as the accessibiHty and success of chiral additives, may have inhibited widespread commerciali2ation. Usually, nondestmctive visuali2ation of the sample spots in tic is accompHshed using iodine vapor, uv or fluorescence. However, the presence of the chiral selector in the stationary phase can mask the analyte and interfere with detection (43). 

Chemical stabiUty studies are monitored by siUca gel thin-layer chromatography (dc) or by high performance Hquid chromatography (hplc) using a reverse-phase C g coated column (24). Hplc peaks or dc spots are visualized by thek uv absorption at 245 nm the tic spots can also be detected by ceric sulfate or phosphomolybdic acid staining. 

Amino acids have high melting or decomposition points and are best examined for purity by paper or thin layer chromatography. The spots are developed with ninhydrin. Customary methods for the purification of small quantities of amino acids obtained from natural sources (i.e. l-5g) are ion-exchange chromatography (see Chapter 1). For general treatment of amino acids see Greenstein and Winitz [The Amino Acids, Vols 1-3, J.Wiley Sons, New York 1961] and individual amino acids in Chapters 4 and 6. 

Since the unpurified toxins show no aldehyde absorption, it was of interest to identify the precursors of helminthosporol and helminthosporal. Thin-layer chromatography of fresh chloroform extracts of the toxin that had been concentrated below 40° indicated several spots (6). One was identified as prehelminthosporol, a hemiacetal (X), from NMR spectra and chemical reactions. Refluxing with triethylamine yielded helminthosporol, identical with Tamura s prod-... 

Thin layer chromatography of (-)-DAG on Silica Gel G using the solvent system, benzene methanol acetone acetic acid (70 20 5 5), shows one spot with Rf 0.7. 

Analyses in the pg range, e.g., in water and oil, can be carried out with thin-layer chromatography [244]. After separation on the thin-layer plates, then by Dragendorff reagent, colored spots are measured with the help of a spectral photometer at 525 nm. 

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... 

Reference substances can be used for confirmation of identity of the substance by, e.g. infrared spectrophotometry where the spectrum of the substance to be examined must be concordant with the spectrum of the GRS, or by thin layer chromatography where the migration and appearance of the spots of both the substance to be examined and the GRS are the same, or by liquid chromatography where the retention time of both the substance to be examined and the GRS are the same. 

---