The retention behaviour of several compounds has been compared for their selectivity using reversed-phase high performance liquid chromatography with binary water mobile phases composed of methanol, acetonitrile or tetrahydrofuran as modifiers.

Shimadzu LC Control Driver for Empower? Software

Efficient extraction of basic drugs from biological matrices using a polymeric cationic mixed-mode sorbent - strata? X-C

High performance liquid chromatography–solid phase extraction–nuclear magnetic resonance (HPLC–SPE–NMR) is a novel hyphenation technology that concentrates single chromatographic peaks to elution volumes matching those of NMR flow probes. The SPE unit facilitates the solvent exchange from the mobile phase of the optimized HPLC assay to a deuterated NMR solvent. The well-defined NMR solvent conditions make spectra comparisons feasible, which means databases and spectra catalogues can be used to swiftly identify analytes. The ability to accumulate analytes on the SPE cartridges by multiple trapping reduces the need to perform residual solvent suppression experiments and allows heteronuclear NMR experiments to be performed overnight. Structure elucidation of natural products directly from crude extract HPLC samples has become the key application of this technique.

This article describes the factors that affect the selection of columns for two-dimensional (2D) LC×LC separations. The maximum increase in peak capacity compared with single-dimension (1D) separations is obtained by using "orthogonal" systems employing various combinations of separation mechanisms to provide as different separation selectivities as possible for the sample compounds in the first and in the second dimension systems. To obtain best results, matching the chemistry of the stationary phase, column dimensions and mobile phases in the first and in the second dimensions is essential for successful separations, especiall for comprehensive LC×LC.

An evaporative light scattering (ELS) detector is a powerful detection tool if the solutes are less volatile than the eluent. Three main processes occur successively: nebulization, evaporation of the liquid chromatographic (LC) effluent and measurement of the light scattering by the residual particles. This leads to a non-linear calibration curve such as, A= a.m b where A is the peak area,m the sample mass and b the response coefficient measured as the slope of Log A = b>Log m + Log a.

his article reveals the first liquid chromatography (LC) separations performed on a microfabricated pillar array column under pressure-driven conditions. The pillars were non-porous and produced using a Bosch-type deep reactive ion etch (DRIE) to pattern the surface of a silicon wafer and had a diameter of approximately 5 μm. Two different packing densities were compared: one similar to the packing density of a packed bed (external porosity of approximately 49%) and one similar to the packing density of monolithic columns (external porosity of approximately 70%).

An overview is presented of possible pathways to enhance peak capacity in liquid chromatography (LC). The peak capacity in a chromatographic separation is directly related to the plate number and thus to column length and particle size. Serial coupled columns can be used to obtain long effective column lengths, reaching over 100000 theoretical plates and peak capacities up to 900. Some theoretical considerations are made on column dimensions and particle size and examples are given of high resolution "GC-like" separations in LC using state-of-the-art LC hardware. Recent developments in LC hardware have also enhanced the applicability of two-dimensional LC–LC and comprehensive LC×LC. Both techniques are extremely powerful to unravel complex samples.