promotion image of download ymail app
BEN 發問時間: 社會與文化語言 · 1 0 年前

gas chromatographic (GC)

How a laboratory gas chromatographic test is performed? I need the answer in English. Thanks very much!

1 個解答

  • 1 0 年前

    In a GC analysis, a known volume of gaseous or liquid analyte is injected into the "entrance" (head) of the column, usually using a microsyringe (or, solid phase microextraction fibers, or a gas source switching system). As the carrier gas sweeps the analyte molecules through the column, this motion is inhibited by the adsorption of the analyte molecules either onto the column walls or onto packing materials in the column.

    The rate at which the molecules progress along the column depends on the strength of adsorption, which in turn depends on the type of molecule and on the stationary phase materials. Since each type of molecule has a different rate of progression, the various components of the analyte mixture are separated as they progress along the column and reach the end of the column at different times (retention time).

    A detector is used to monitor the outlet stream from the column; thus, the time at which each component reaches the outlet and the amount of that component can be determined. Generally, substances are identified (qualitatively) by the order in which they emerge (elute) from the column and by the retention time of the analyte in the column.

    若不清楚上述之程序,可以參考下面的連結網站喔! (參附圖"Diagram of a gas chromatograph.")

    • Commenter avatar登入以對解答發表意見