Thin-layer chromatography of hydroxyanthraquinones in plant extracts

Summary Existing thin-layer chromatographic (TLC) methods for the separation of hydroxyanthraquinones in plant materials were found to have limited applications. This initiated the development of some new TLC systems to separate the five principal hydroxyanthraquinones: chrysophanol, physcion, emodin, rhein and aloe emodin normally present together in plant materials, on a single chromatogram and usually with a single solvent system.     

Thin-layer chromatography of isomeric pairs of chalkones and flavanones

Summary A fundamental two-dimensional thin-layer chromatographic technique using silica gel as adsorbent for the detection and identification of isomeric pairs of chalkones and flovanones is described. The proposed method is simple, inexpensive and needs no sophisticated instruments.     

Thin-layer chromatography of metal ions on bonded stationary phases

Summary The separation of iron, copper, nickel, and zinc by thin-layer chromatography was studied. Eight bonded-phase silica substrates and twenty-nine solvent systems were investigated. Solutions of 1% diphenylcarbazide in ethanol and 1% K₄Fe(CN)₆ in water were used to detect the metal ions. The best separation was obtained with an immobilized trifluoroacetylacetone substrate and 10% trifluoroacetylacetone in acetone mobile phase.     

Thin-layer chromatography of low-molecular epoxy compounds after derivatization with picric acid

Summary Optimum conditions were obtained for the determination of low-molecular epoxides by a method based on derivatization with picric acid and thin-layer chromatography on silica gel. The chromatograms were visualized with solutions of primary, secondary or tertiary amines in acetone. Most of the monoepoxides gave only one spot; diepoxides gave two spots. The detection limits for highly reactive epoxy compounds (derivatization time less than 2 hours) were estimated to be approx. 0.02 μmole.     

Thin-layer chromatography with biological detection in phytochemistry

Bioautography on thin-layer chromatographic (TLC) plates is a means of detecting the biological activity of a sample which has migrated on the plate with a suitable solvent. It only requires small amounts of sample and is ideal for the investigation of plant constituents, which often occur as complex mixtures. It can be used for the target-directed isolation of these constituents. In contrast to HPLC, many samples can be run at the same time on TLC. Organic solvents, which cause inactivation of enzymes or death of living organisms, can be completely removed before biological detection. Many bioassays are compatible with TLC. Antimicrobial, radical scavenging, antioxidant activities and enzyme inhibition feature among the tests that are employed.     

Thin-layer chromatography of binary mixtures of metal complexes including isomers

Summary Complexes of 2,6 pyridine-bis-glyoxal-o-mercaptylanil and thiophene-2-glyoxal-o-pyridineanil with Fe(III), Co(II), Ni(II) and Cu(II), isolated as binary mixtures, were quantitatively resolved on thin layers of silica gel and their compositions were determined. Separation of mixtures in bulk was by column chromatography. Resolved components, including cis- trans and structural isomers, were identified by correlating their R_F values with spectral properties.     

Thin-layer chromatography of benzamides on cellulose and unconventional starch and aminoplast supports

Summary The retention behaviour and separation ability of cellulose, starch and aminoplast thin-layers with aqueous and non-aqueous mobile phases has been studied by measuring the retention of a homologous series of benzamides. The retention behaviour and separation ability are discussed in terms of the nature of the solute, support and eluent.     

Thin-layer chromatography of metal ions on a new carbamide-formaldehyde polymer

Summary A number of metal ions were systematically chromatographed on thin-layer of a newly synthesized carbamide-formaldehyde polymer using neutral and acidic eluents. For comparison, metal ions were also chromatographed on cellulose layers with the same eluents.     

Thin-layer chromatography for the identification and semi-quantification of biogenic amines produced by bacteria

The screening TLC method described enables the simultaneous identification and semi-quantification of eight biogenic amines with a large number of samples handled in a short period of time. The dansylation process time was drastically reduced from 80 to 18 min by increasing the reaction temperature to 100 °C. Bacteria could be classified as no, low, moderate or powerful amine producers when no spots were noticeable in TLC plates, less than 50 mg/L, from 50 to 500 mg/L, or more than 500 mg/L of amines were present in the decarboxylase broth medium, respectively. This TLC method is a simpler, faster and less expensive alternative to other methods, such as differential culture media, HPLC and even more sensitive than other TLC procedures.     

Thin-layer chromatographic separation of some closely related olefinic benzo- and naphtofurans

Summary A method is reported for the separation of 16 closely related 2-(1, 2-diphenylvinyl)-3-phenylbenzofuran and 2-(1, 2-diphenylvinyl)-1-phenylnaphtho[2,1-b] furan derivatives on thin-layers of silica gel-G.     

Headspace analysis of chlorinated organic solvents in aerosol cans by gas chromatography

Summary A gas chromatographic (GC) method for the analysis of chlorinated solvents in chemical products in aerosol cans is described. Conditions for the sampling of chemical products from aerosol cans were optimized, so that the recovery of the solvents was better than 90%. Chlorinated solvents were identified by headspace GC—electron capture detection (ECD) as well as by GC — mass spectrometry. Headspace analysis employing the standard additions method and GC-ECD was used for the quantitation of chlorinated solvents. Analysis of 159 acrosol products, for various uses, revealed that 9% of these did not comply with the Danish Aerosol Regulations. The results of the study further indicated that aerosol products for haircare, paints and paint removers, and many others, can be formulated without chlorinated solvents.     

Simultaneous determination of trace level bromate and chlorinated haloacetic acids in bottled drinking water by ion chromatography

A convenient and sensitive method for the simultaneous determination of trace level of bromate and chlorinated haloacetic acids in bottled drinking water with ion chromatography is presented. With a high capacity anion-exchange column and 11.5 mmol/l Na₂CO₃ eluent, all the 16 analytes could be separated in one injection within 31 min. By employing a microwave based evaporation technique, the bottled drinking water sample could be concentrated tenfold in 10 min. The recoveries of the compounds ranged from 90.6 to 107.2%. With a 500 μl large volume injection and high performance anion Atlas electrolytic suppressor, the detection limits were 0.06, 0.08, 0.06, 0.14 and 0.85 μg/l for BrO₃⁻, ClO₃⁻, monoacetic acid, dichloroacetic acid and trichloroacetic acid, respectively.     

Thin-layer chromatography of inorganic ions on polyethyleneimine cellulose in sulfuric acid and acid-ammonium sulfate media

Summary The thin-layer chromatographic behavior of 49 inorganic ions on polyethyleneimine (PEI) cellulose, a weakly basic anion-exchanger, has been systematically studied in sulfuric acid and ammonium sulfate media (both 0.01–1.0 moldm⁻³). The sorption on the cellulose decreases with increasing concentration of the acid or sulfate for most of the ions and to a lesser extent for Hg(II), Bi(III), Th(IV), Nb(V), and U(VI). The R_f values of Pd(II), Ru(III), Au(III), Pt(IV), and Ta(V) are extremely low in both systems. Ba(II), Pb(II), Sb(III), Mo(VI), and W(VI) are also strongly retained on the layer. Oxy-anions such as As(III) and Se(VI) are not adsorbed on the cellulose to any great extent, but Re(VII) distributes on the plate with a R_f value of about 0.5. The characteristic retention on PEI-cellulose layer of several polyvalent ions, which form anionic sulfato complexes, can be observed in ammonium sulfate media. Possibilities for separations of analytical interest are also demonstrated in both systems.     

Thin-layer chromatography and densitometry of anthocyanins in the petals of red poppy during development of the flowers

Summary The variation in anthocyanins content of the petals of red poppy (Papaver, Rhoeas) during development of the flower from the closed bud stage have been investigated. Six-stage gradient thin-layer chromatography of the polyzonalstepwise type was used, starting from ethyl acetate, the last eluent fraction being isopropanol-water-acetic acid (65323). Silica Si 60 was used as adsorbent. The densitograms were recorded at 465 nm; they show gradually increasing peaks of red anthocyanins in the petals of closed buds, partly opened buds and fully developed flower and changes in the proportions of several anthocyanins, with various R_F values, during the growth of the flower.Editor's note: see also J. P. Goiffon, M. Brun and M.-J. Bourrier, J. Chromatogr.517, 101 (1991)     

Thin-layer gel chromatography of 8-hydroxyquinoline metal complexes

Gel chromatographic behavior of 8-hydroxyquinoline (oxine, abbreviated HOx) complexes of zinc, copper, aluminum, gallium and indium has been investigated on thin layers of Styragel 60A and Merckogel OR-PVA 2000 mostly in chloroform and p-dioxan media. Except for the stable Cu(Ox)₂, the other oxinates exhibit either hydration or decomposition in gel-solvent-solute systems, which leads to strong retention or tailing on gel layers. An excess of 8-hydroxyquinoline present in solvents allows the oxinates to be stabilized, so that well-defined compact spots come out and migrate. For the Zn(Ox)₂ the formation of a self-adduct is strongly suggested on the basis of gel chromatographic behavior. Elution with the solvent containing pyridine also yields evidence of the adduct formation of zinc oxinate-nitrogen base.     

有机铁硫原子簇化合物薄层色谱展开剂优化快速选择

本文介绍了薄层色谱最佳展开剂组成的快速选择方法。首先利用对半优化法粗选最佳展开剂大概用量范围;其次绘制△Rt-ε0图预测展开剂系统:最后用数字分析法算出展开剂各组分最佳配比值。并用于有机铁硫原子簇化合物[1,2]的薄层分析。     

Thin-layer chromatography of ecdysteroids originated fromSilene otites L. (Wib.)

Summary Thin-layer chromatographic investigations of ecdysteroids have been carried out to monitor their isolation by column chromatography and droplet countercurrent chromatography as well as to control the homogeneity of the pure products. Isolation scheme and chemical structure of the 20-hydroxyecdysone-22-benzoate and that of three new ecdysteroid compounds, 2-deoxy-1,20-dihydroxyecdysone, 2-deoxyecdysone-22-acetate and 2-deoxy-20-hydroxyecdysone-22-acetate are also presented.     

Thin-layer adsorption chromatography with mixed mobile phases. 4. Extension of Ościk's equation to heterogeneous adsorbents

In this paper the equation for thin-layer adsorption chromatography with multicomponent mobile phases, proposed by O?cik in 1965 is extended to energetically heterogeneous solid surfaces. Other forms of this equation, more convenient in practical applications, are presented. Model calculations are made for TLC with binary mobile phases according to the modified form of O?cik's equation. Finally, this equation is compared with that of Snyder.