Comparison of a UPLC Method across Multiple UHPLC Systems
September 8th 2005In 2004, Waters introduced the ACQUITY UPLC® System. Since this launch, many liquid chromatography (LC) vendors have introduced modified high-performance liquid chromatography (HPLC) systems designed for ultra-high-pressure liquid chromatography (UHPLC). Although these systems may provide satisfactory performance for analytical-scale compressed chromatography (4.6-mm I.D.), they struggle significantly to provide high-resolution chromatography with sub-2-μm microbore columns (2.1-mm I.D.), which require a system designed to maximize the separation efficiency.
Method for Heart-Cut Analysis Using Nanoacquity UPLC With 2D Technology for Proteomic Samples
September 8th 2005A biomarker is measured as an indicator of normal biological processes, pathogenic processes, or pharmacologic responses to therapeutic intervention. Many times, a putative biomarker is a protein or peptide that is expressed at a relatively low level compared to the surrounding proteome. The constitutive or housekeeping proteins are present in concentrations that are orders of magnitude above the protein of interest, which makes identification and quantitation difficult. In order to validate a candidate biomarker, many samples need to be analyzed to prove that the same analytes are reproducibly identified and are changing in a statistically significant manner due to a perturbation.
Comparison of a Fast HPLC Method across Multiple LC Systems
September 8th 2005Since the introduction of the Waters® ACQUITY UPLC® System, many vendors have introduced modified high-performance liquid chromatography (HPLC) systems designed for fast LC or ultra-high-pressure liquid chromatography (UHPLC). These systems, which can yield satisfactory chromatography at an analytical scale (4.6-mm I.D.), where system volume and system bandspread have less of an impact on peak width, struggle significantly with microbore chromatography (2.1-mm I.D.). These low-volume separations require a system designed to maximize the separation efficiency to provide greater quality information for the user.
The Use of Thin-Layer Chromatography with Direct Bioautography for Antimicrobial Analysis
September 1st 2005This article gives an overview of screening methods for the detection of antimicrobials, including dilution and diffusion methods and bioautography, mainly direct bioautography. The thin-layer chromatography method with direct bioautography was worked out to analyse enrofloxacin and ciprofloxacin residues in milk.
Practical Electromigration Techniques to Separate Microorganisms in Medical Analysis
September 1st 2005This article looks at the use of electromigration techniques to determine microorganisms, such as viruses, bacteria and other biologically important macromolecules (erythrocytes), in medical analyses. It was found that electromigration techniques could be used for the identification of several viruses, including the identification of a specific marker for the Hepatitis C virus infection and another for a urinary tract infection. The determination of cell viability and the quality control of probiotics and consumer products that contain active bacteria is also possible using electromigration. Special attention is paid to the modification of capillary wall surfaces using different monomers and the application of monolithic columns to determine active bacteria in pharmaceutical products using capillary electrochromatography (CEC) conditions. This approach represents a new frontier for separation science and the possibility to apply it in medical diagnosis.