Enriching volatile compounds by a temperature gradient tube

Abstract

Environmental analysis needs quantitative determinations and identification at concentration levels which are out of reach of most direct working analytical systems. Ethylene in air, a very active hormone for plants, kills some flowers within 24 hours when its concentration level reaches 10~7% (v/v). Many other reactions of ethylene with plants have been reported by D. Zimmerman (1), H. O. Kunkel (2), and F. B. Abeles (3), showing that ethylene in air has to be controlled to well under its lethal dose of 10~7% (v/v) for plants.Even at a distance of 15 miles from a chemical factory, ethylene emission can reach levels higher than 10_5% (w/w). This is only one example where specific analysis in environmental control is necessary by specific enrichment, separation, and detection of a single compound.

Sampling and analysis of trace-organic constituents in ambient and workplace air at coal-conversion facilities

“…Partial loss of the sample may occur if a microfog is produced in the trap (Kaiser, 1973). (P.art of the sample may pass through instead of condensing on the walls of the trap.…”

“…Westberg et al (1974) sampled the urban air of both Houston and Phoenix for light hydrocarbons ( C2-C6). Cudney et al ( 1977) and Kaiser ( 1973) used .cryogenic tubes packed with solid adsorbents to trap Cl-C6 hydrocarbons.…”

“…Kaiser (1973) used a molecular sieve i~ a gradient cooled (-20 to -160°C) trap to collect C1-C4 hydrocarbons from traffic air. Pellizzari et al ( 1976b) found Carbosieve B to be less satisfactory than Tenax GC for general hydrocarbon analysis.…”

The analysis of organic compounds in water by direct adsorption and thermal desorption

“…A number of workers have designed systems for thermal desorption from Tenax traps (41)(42)(43)(44). The most recent of these are simply heated insertion probes containing the Tenax trap from a gas purge sampling device (45)(46).…”

“…Two of the most Important sampling problems are sample degradation (36,^8) and losses through sample adsorption on container walls (42,49). In many instances great care must be taken to prevent almost quantitative losses.…”