Search results for "Thin-layer chromatography"

Thin-layer chromatography of 2-methyl-4-chlorophenoxyacetic acid and its soil metabolites

1980

Abstract The thin-layer chromatography of 2-methyl-4-chlorophenoxyacetic acid, 4-chloro- o -cresol and 3-methyl-5-chlorocatechol and their pentafluorobenzyl derivatives has been studied on silica gel as adsorbent with 19 solvent systems. The best separation of the individual components occurred with toluene-benzene-acetic acid (2:2:1). Chloroform-diethyl ether-toluene (1:1:1) was suitable for the group separation of the pentafluorobenzyl derivatives.

Synthesis and characterization of alumina R chemically modified withn-octyl for use as a stationary phase in TLC

2003

A stationary phase for thin-layer chromatography has been prepared by attaching 1-octene to alumina R. This stationary phase has been characterized by elemental analysis, measurement of specific surface area, IR spectroscopy, and by chromatographic testing.

Molecular topology and chromatographic retention parameters for benzodiazepines

1992

Abstract The relationship between gas-liquid chromatographic (GLC) retention properties and R F values in thin-layer chromatography (TLC) with molecular connectivity indices, m X t , was investigated for a series of benzodiazepines using multiple correlation coefficients, standard errors of estimate, F -Snedecor function values and Student's t -test as the criteria for best equation selection. Regression analyses show that the molecular connectivity model predicts the retention properties in GLC with the polar stationary phase OV-17 at 280°C and the R F values in TLC with the stationary phase silica gel. However, zero- or second-order connectivity indices alone are not sufficient; higher-or…

Separation of U(VI) and Th(IV) from Some Rare Earths by Thin Layer Chromatography with Di‐(2‐Ethylhexyl)‐Dithiophosphoric Acid on Silica Gel

2005

Abstract Separation of U(VI) and Th(IV) from some rare earths by TLC has been studied using silica gel H and silica gel H impregnated with ammonium nitrate as the stationary phase. The solvent mixture ethyl‐methyl‐ketone–tetrahydrofuran (6∶3, v/v) containing di-(2‐ethylhexyl)-dithiophosphoric acid was used as the mobile phase. When silica gel H impregnated with 2.5 M NH4NO3 was used as stationary phase, the resolution was much improved and the separation of rare earths from each other was also achieved. The tetrad‐effect was observed in variation of R*m versus the atomic number of rare earths.

Thin-layer chromatography of chlorinated anisoles and veratroles

1989

The thin-layer chromatography of chlorinated anisoles (methoxybenzenes) and veratroles (1,2-dimethoxybenzenes) has been examined on silica gel G60 and RP-18 thin-layer plates. More than fifty solvent systems were screened and some of them recommended for particular separations. Acetone was shown to be suitable for group separation of both chlorinated anisoles and veratroles on a silica gel G60 stationary phase having a very narrow range of RF values. On the other hand, benzene, dichloromethane and the various mixtures of light petroleum (b.p. 40–60°C) and a more polar eluent (such as diethyl ether, acetone or ethyl acetate) were recommended for separation of certain individual isomers. The …

Quality control of commercial mustard by thin-layer chromatography

2005

Horseradish samples ( Cochlearis armoracia L. ) and mustard samples ( Sinapis alba L. ) were extracted with 70:30 ( v/v ) methanol-water in accordance with ISO method 91671. Samples of commercial mustard with and without horseradish were submitted to the same extraction procedure. Separation of the active compounds from these samples were performed on silica gel 60 plates with preconcentration zone and on silica gel F 254 high-performance thin-layer chromatography plates, with iso -propanol-25% ammonia, 90 + 10 ( v/v ), containing different volumes of distilled water (1, 2, 3, or 5 parts), as mobile phases. After development the compounds were visualized in UV light at λ = 254 nm or by expo…

Chromatographic fingerprint, antioxidant activity, and colour characteristic of polish goldenrod (Solidago virgaurea L.) honey and flower

2018

In recent times, the nutraceutical and pharmaceutical interest in honey due to its well-known health properties has increased. Consumers need clear and precise information, so that they can make informed choices about their diet and the foods they buy. Therefore, gas chromatography–mass spectrometry (GC–MS) and high-performance liquid chromatography with a photodiode array detector (HPLC-PAD) was revealed a general characteristic fingerprint of polish monofloral goldenrod honey and flowers. In addition, high-performance thin-layer chromatography (HPTLC) has proven to be a useful tool for determining similarity patterns of common bands among honey from the same floral source and thus can be …

Quantitative determination of moniliformin in vegetable foods and feeds

1984

A suitable and simple method for the quantitative determination of moniliformin in vegetable foods and feeds is described. The mycotoxin was extracted by Soxhlet extraction with methanol from mouldy maize, rice, rye, oats, wheat and barley samples. Moniliformin was determined by thin-layer chromatography (TLC) using N-methylbenzthiazolon-2-hydrazone (MBTH) as a new derivatization reagent for this mycotoxin. The moniliformin derivative was assayed at 518 nm. Quantification could be performed after calibration. A linear relationship between mycotoxin amount and peak area was found from 100 to 400 ng/spot. The detection limit is 75 ng/spot.

Simultaneous clean up of fish fat containing low levels of residues and separation of PCB from chlorinated pesticides by thin-layer chromatography

1974

Über die synthese methylsubstituierter p-oligophenylene durch oxydative verknüpfung aus lithiumorganischen verbindungen. 19. Mitteilung über poly- un…

1966

Die oxydative Verknupfung von Lithiumarylen wurde an den isomeren Lithiumtoluylen als Modellverbindungen studiert. Die Darstellung von 4,4′-Dilithium-3,3′-dimethylbiphenyl und von 11,44-Dilithium-12,23,32,43-tetramethyl-p-quaterphenyl wird beschrieben. Die oxydative Polykondensation dieser Dilithiumverbindungen mit Hilfe von CuCl2 wurde in verschiedenen Losungsmitteln untersucht. Als Hauptreaktionsprodukte entstehen die erwarteten Verbindungen mit 8 bis 12 p-verknupfte Phenylenbausteine. Aus dem Reaktionsgemisch wurde das 12,233,2,435,2,63,72,83,92,103,112,123-Dodekamethyl-p-duodeciphenyl durch praparative Dunnschichtchromatographie in hoher Reinheit isoliert. Die Darstellung des 12,23,32,4…