Document Type


Date of Award

Fall 1-31-1993

Degree Name

Master of Science in Environmental Science - (M.S.)


Chemical Engineering, Chemistry and Environmental Science

First Advisor

S. Mitra

Second Advisor

Barbara B. Kebbekus

Third Advisor

Leonard Dauerman


A thermal desorption modulator is made from a short segment of thin tubing containing an adsorbent or a chromatographic stationary phase. A carrier gas containing the analyte is introduced into the analytical column through the modulator which acts as a sample trap. Rapid electrical heating of the modulator releases a "concentration pulse" of the analyte and this serves as an injection similar to that from an injection valve. The modulator also acts as a sample preconcentrator and can be used to make repetitive injections every few seconds. In this research, the mechanism of thermal desorption modulator was studied and was used in continuously monitoring volatile organic pollutants.