Vapor‐phase sampling

Abstract

Two new sample preparation procedures that produce solvent‐free extracts especially suitable for use with high resolution GC are described. One is based on Soxhlet extraction in a pressurized container that permits the use of liquid carbon dioxide as the extractant; the other utilizes refluxing difluorodichloro‐methane (Freon 12) to isolate entrained volatiles from gas streams.

Isolation and concentration techniques for capillary column gas chromatographic analysis

“…Vapor phase sample preparation methods related to distillation are summarized in Table l . Sweep co-distillation [16,17], co-distillation and solvent extraction [I 81, reflux trapping [19], and sublimation [20] provide relatively clean samples which can often be analyzed directly by capillary column gas chromatography without further sample cleanup. Table 2 summarizes methods suitable for determining trace organic compounds in water [21].…”

“…Jennings has described a pressurized system permitting the use of liquid carbon dioxide with a standard glass Soxhlet extractor forthe extraction of solid samples and for the recovery of organicvolatilesfrom adsorbents [19]. This extractor, which can utilize dry ice as a source of carbon dioxide, has the advantage of achieving high extraction efficiencies under an inert atmosphere and at low temperatures.…”

Comparison of extraction methods for the determination of polycyclic aromatic hydrocarbons in soot samples

“…The relatively recent procedure with liquid CO z was investigated in more detail concerning the necessary number of transfers for complete extraction and the proper method to remove the CO 2 after completion of the extraction process. Opening the valve to allow evaporation of the liquid CO2, which is in general suggested [13,14] showed strongly decreased recoveries of the PAH. An improved method will be discussed.…”

Flavor Analysis

“…Extraction equipment costs have resulted in limited use of supercritical C0 2 in the flavor research laboratory. Jennings (1979) has developed a rather simple system for the extraction of solids with liquid C0 2 . The solids may be a food material or a "loaded" porous polymer headspace trap (e.g., Tenax).…”