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  • separations and wet chemistry

    The separations and wet chemistry group specializes in chromatographic techniques for trace analysis and classical wet chemical analysis.

    gas chromatography

    Gas chromatography (GC) is a universal separation technique applicable to complex mixtures. The technique uses differences in volatility and analyte-column interaction to achieve the desired separation. GC is commonly used to analyze mixtures for identification and quantification. Various ancillary GC techniques, such as headspace/GC-MS, and other multidisciplinary techniques, are available to solve client problems. GC techniques encompass a wide range of analytical problems. Assay and trace-level analyses are achieved with minimal sample preparation. A wide variety of special detectors is available for quantification and specific identification of various classes of compounds.

    gel permeation chromatography

    Gel permeation chromatography (GPC), also known as size exclusion chromatography, is an analytical technique that determines the molecular weight distribution (MWD) of a polymer by virtue of its hydrodynamic volume. Molecular weight averages, such as Mn, Mw and polydispersivity, are also characterized by GPC. The size and shape of polymeric molecules determine physical and processing properties and are critical to producing a product with the desired performance characteristics. This technique applies to any solvent soluble polymeric material.

    high-performance liquid chromatography

    The strength of high-performance liquid chromatography (HPLC) lies in its versatility, sensitivity and selectivity. This chromatographic technique uses different mobile phases and columns to achieve the necessary separation of polar, thermally labile, non-volatile and other analytes that cannot be analyzed by gas chromatography. HPLC is non-destructive and analytes can be isolated for further spectroscopic analysis. Very low detection levels are achievable and multiple detectors can be used in series to monitor specific analytes. A wide variety of detectors are used including electrochemical, variable wavelength UV/visible, diode array and mass spectrometers. These are used to measure electrochemically active compounds, high molecular-weight analytes and non-UV absorbing materials.

    inductively coupled plasma-optical emission spectroscopy

    Inductively coupled plasma-optical emission spectroscopy (ICP) is used for high-sensitivity elemental analysis. The spectrometer has the capability to measure from lithium through the periodic table (excluding the halogens) at mid-part-per-billion (ppb) levels. Semi-quantitative scans can provide elemental composition information at several hundred ppb levels for most elements. Samples can be analyzed in aqueous as well as organic matrices.

    ion chromatography

    lon chromatography is a separation technique used to examine aqueous samples for anions, cations and trace levels of organic acids. Ion chromatography is similar to high-performance liquid chromatography in that it requires a liquid mobile phase and a column with a stationary phase. Ions that have a higher affinity for the stationary phase elute more slowly than ions that have a lower affinity for the stationary phase.

    classical wet chemistry

    AS&T provides analytical testing using classical wet chemistry techniques that conform to procedures of the ASTM and the Society of the Plastics Industry. These procedures are applied to analyses of coating resins, plastics, adhesives and phenolics. They include Karl Fischer water determination, pH measurements and auto titration capabilities.

  • 丢掉再次谈判的幻想,中国要作好长期与美国打贸易战的准备。这并不是我们好战,完全是因为特朗普是一个出尔反尔、六亲不认、利欲熏心、执意与世界为敌的疯子。我们必... 2019-08-18
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  • 郑良发的专栏作者中国国家地理网 2019-07-28
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