Search results for "CHROMATOGRAPHY"

Gas chromatographic study of acetyl derivates of chlorinated guaiacols

1982

The gas chromatography of acetyl derivatives of guaiacol and all chlorinated guaiacols has been studied on SE-30, OV-351 and Carbowax 20M capillary columns. The retention order and relative retention times under isotermal and temperature-programmed conditions are discussed. Different retention times for all mono- and dichloro compounds have been observed on the SE-30 column. However, all trichloroguaiacol isomers were separated only on polar columns. The best overall temperature-programmed separations have been achieved on an SE-30 capillary column.

Eine quantitative Bestimmungsmethode des Uracilgehaltes biologischen Materials im Nanogramm-Bereich mit Hilfe der Hochdruck-Flüssigchromatografie / A…

1974

Abstract A method is described for the estimation of the uracil content in biological materials by means of high-pressure liquid chromatography. Hydrolysis of the tissues and total liberation of RNA bases are carried out in 70% perchloric acid. Less than 1 mg of the materials are needed for analysis. A pre-purification of the hydrolyzates is carried out by anion-exchange chromatography. Recoveries are estimated by isotope dilution analysis with [2-14C] labelled uracil. The method is highly sensitive - about 6000 pmol of uracil content can at least be estimated quantitatively - and analysis time is short. In routine analysis a single sample needs 4 hours to be completed. When preparing sever…

New Glass Capillary Gas-Chromatographic Methods for Metabolites in Urine and Serum

1981

The analytical system suggested in this paper is a further development of pre-chromatographic methods and of column switching techniques described in previous papers1,2,3.In order to use modern gas-chromatographic techniques for the determination of metabolites in urine and serum quick and reliable pre-chromatographic methods for extraction, concentration and derivatization must be developed which give final (dosage) volumes of 5 to 10 μl with starting sample volumes of 0.1 ml of urine or 5 ml of serum as described by Dunges4.

Comparative study on the column performance of microparticulate 5-μm C18-bonded and monolithic C18-bonded reversed-phase columns in high-performance …

1999

In this paper we report on the results of a comparative study on the performance of Purospher RP 18e, 5 μm, columns and prototypes of monolithic columns named SilicaROD from Merck, Darmstadt, Germany. The studies were performed on HPLC equipment with minimum extra column contribution. The plate height linear velocity dependency of the Purospher RP 18e column showed a minimum of H of about 10–15 μm at a linear velocity of 1 mm/s. The H versus u curves of the monolithic columns followed the same course. Yet, the curves remained flat up to a linear velocity of about 7 mm/s, where the Purospher RP 18e column could not be operated anymore due to the extremely high back-pressure. In conclusion th…

Two-dimensional liquid chromatography - high resolution mass spectrometry method for simultaneous monitoring of 70 regulated and emerging mycotoxins …

2020

Time-dependent monomerization of gramicidin A, enhanced by phosphatidylcholine in non-polar solvents

1986

Abstract The usefulness of size-exclusion high-performance liquid chromatography for the study of gramicidin A dimer—monomer conformational equilibrium in non

Hydrodynamic chromatography of macromolecules on 2 μm non-porous spherical silica gel packings

1989

Non-porous spherical 2μm silica gel particles have been tested as packing for hydrodynamic chromatography of macromolecules (HDC). Columns packed with these particles in 250×4.6mm i.d. columns can be operated very efficiently (e.g. a reduced plate height of about 2) when the detection cell is miniaturized. The packing is suitable for the separation of polystyrenes of Mw of 104–107 by hydrodynamic chromatography and the retention behaviour of polystyrenes agrees well with the known theoretical models. Preliminary results on the applicability of HDC for the separation of biopolymers are presented.

Thin-layer chromatography of chlorinated catechols on a silica gel 60 layer

1981

Multivariate correlation between13C and31P NMR spectral data on dissolved lignin and the combustion properties of kraft black liquor

1999

Validation of Methylmercury Determinations in Aquatic Systems by Alkyl Derivatization Methods for GC Analysis Using ICP-IDMS

2001

Isotope dilution mass spectrometry (IDMS), using an inductively coupled plasma quadrupole mass spectrometer (ICPMS) and a species-specific methylmercury spike was applied to validate the commonly used GC method for methylmercury (MeHg+) determination, which is based on the formation of volatile methylethylmercury by derivatization with NaBEt4. The spike compound, Me201Hg+, was synthesized by reaction of 201Hg-enriched mercury chloride with methylcobalamin. By analyzing different environmental aquatic samples, it was found that in most cases, transformation of MeHg+ into elemental mercury (Hg0) took place. From investigations of synthetic solutions, it could be followed that halide ions are …