STP957: Special Calibration Systems for Reactive Gases and Other Difficult Measurements

    Dorko, WD
    National Bureau of Standards, Center for Analytical Chemistry, Gaithersburg, MD

    Hughes, EE
    National Bureau of Standards, Center for Analytical Chemistry, Gaithersburg, MD

    Pages: 6    Published: Jan 1987


    Abstract

    The most popular method for determining a component of interest in a gas mixture is to use a detector that responds to the analyte and is calibrated directly with a cylinder gas mixture containing the analyte at the approximate concentration of interest. In many instances, however, this cannot be achieved; cylinder calibration mixtures may be unstable or the direct response detector may not be sensitive enough. The unstable cylinder mixture can be replaced by a dynamic dilution gas calibration system where the analyte can be introduced by any one of several means including permeation devices, or a higher concentration gas mixture that can be more easily stabilized. If the detector for the analyte is insensitive or difficult to calibrate, then the analyte can be converted to another compound for which there is a detector that is sufficiently sensitive and easy to calibrate.

    In the case of analytical systems, such as gas chromatography, where separation occurs, a mixture of a stable gas can be used to calibrate for a reactive gas if the relative detector responses are known. There is no one particular way to either provide calibration mixtures for the analysis of all reactive gases or to provide a means for the determination of difficult compounds. Any system that will produce a mixture of the required concentration, of acceptable uncertainty, and of stability sufficient for the analysis at hand can be a special calibration system.

    Keywords:

    calibration systems, gas mixtures, reactive gases, calibration standards


    Paper ID: STP25708S

    Committee/Subcommittee: D22.01

    DOI: 10.1520/STP25708S


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