two dimensional thin layer chromatography on polyamide sheets is a useful method for identification of pth-amino acids which have very close rf-values. the solvent systems described here are particularly effective and have an edge over other solvent systems used for the separation of pth-amino acids. the solvent systems provide a clear separation of all pth-amono acids except lle / leu in a rel...

Comprehensive two-dimensional liquid chromatography (LC×LC) using the Agilent 1290 Infi nity 2D-LC Solution with DAD and MS detection is applied for the analysis of citrus oils. The developed method uses normal phase liquid chromatography in the fi rst dimension and reversed-phase liquid chromatography in the second dimension. This combination provides good orthogonality and is valuable for pro...

BACKGROUND Ginsenosides are the major effective ingredients responsible for the pharmacological effects of ginseng. Malonyl ginsenosides are natural ginsenosides that contain a malonyl group attached to a glucose unit of the corresponding neutral ginsenosides. METHODS Medium-pressure liquid chromatography and semipreparative high-performance liquid chromatography were used to isolate purified...

The requirements of liquid chromatography (LC) separation systems to separate proteins are often different from those of small molecules as the inherent properties of proteins can result in loss by adsorption, precipitation at zero charge or broad and asymmetric peaks in liquid chromatography. This article looks at the specific separation problems of proteins; the advantages and disadvantages o...

Bottom-up proteomics provides often small amounts of highly complex samples that cannot be analysed by direct mass spectrometry (MS). To gain a better insight in the sample composition, liquid chromatography (LC) and (comprehensive) two-dimensional (2D-LC or LC × LC) can coupled to MS. Low-flow separations are attractive for HRMS analysis, but they tend lengthy. In this work, low-flow, online, ...

High-performance liquid chromatography (HPLC) and electrophoresis are phase separation methods frequently used in various research fields. Although their origins sufficiently old, the development of novel based on HPLC still required for both fundamental applicational functions. In this paper, we introduced our studies analytical toward enhancing efficiency. The contents can be categorized as f...

we have used a variational approach to calculate some thermodynamic properties of the quasi-one dimensional liquid 3he such as the energy, entropy, free energy, equation of state and heat capacity at finite temperature. we have employed the lennard-jones potential as the inter-atomic interaction. we have seen that the total energy increases by increasing both temperature and density. as expecte...

Two bioactive coumarins including 7-hydroxycoumarin (umbelliferone) and 7-hydroxyl-6-methoxy-3, 70-dicoumarylether (daphnoretin) were separated from the ethyl acetate extract of the stems of Edgeworthia chrysantha Lindl (E. papyrifera) by high speed countercurrent chromatography (HSCCC). The two-phase solvent system used was composed of n-hexane-ethyl acetate–methanol–water at an optimized volu...