A NEW, HIGH SENSITIVITY GAS CHROMATOGRAPHIC DETECTOR WITH RESPONSE BASED ON DIELECTRIC PROPERTIES OF CONSTITUENTS.
Final scientific rept., 1 Sep 64-28 Feb 66,
FLORIDA UNIV GAINESVILLE DEPT OF CHEMISTRY
Pagination or Media Count:
A detector was developed consisting of 2 Clapp oscillators that were beat, by a diode mixer circuit, to give a difference frequency that was measured by use of a frequency meter and a recorder. The tank circuit of the sample oscillator contained a cylindrical condenser through which the carrier and sample gases passed the reference oscillator had a variable air capacitor in the tank circuit. The response of this detector was several orders of magnitude greater than would be predicted for an ideal dielectric constant recorder. The same circuitry could be used for either an RF or a dielectric constant detector, i.e. if a high Q tank coil and a capacitor with closely spaced plates were used, an RF detector resulted, but if the tank were of lower Q and the capacitor had wider plate spacing or large plate area, a dielectric constant resulted. A study was then undertaken to optimize experimental parameters. For most molecules, the limiting detectable sample size is about 10 to the -10th power grams per second, and the range of sample sizes over which near linearity of response occurs is about 1000-fold for non-organic gases.
- Inorganic Chemistry
- Test Facilities, Equipment and Methods