Purge trap materials used

Table 2.11 List of trap materials used in the purge and trap procedure with details of applications and recommended analysis parameters. 

Three purge and trap methods are used to determine 29 halocarbons (Method 601), seven aromatics (Method 602, including four of the halo-carbons), and acrolein and acrylonitrile (Method 603). The three methods are distinctly different in the sorbent trap materials, GC columns, and... 

An IBM IR-98 spectrometer was used for all FT-IR/PAS measurements. The photoacoustic cell used was built at Ames Laboratory. Resolution for all PAS measurements was 8 cm, and no smoothing function was used. Helium passing through a liquid nitrogen trap was used to purge the sample chamber and as conducting gas inside the PAS cell. Carbon black was used as a reference material. Optical velocities corresponding to various mirror velocities of the interferometer are presented in Table I. 

The discussion of headspace methods for blood alcohol and solid-phase micro extraction (SPME) in Section 4.2 introduced the concept of creating an enriched head-space above a sample. Headspace methods may be passive or active and may involve heating the sample. Dynamic headspace (DHS) methods, used in arson analyses, exploit the equilibrium at the liquid-sample interface by sweeping tire headspace with a constant stream of gas, usually helium. DHS is also referred to as purge-and-trap (FT), allhough the latter can also mean a specific t) of sample preconcentrator used in environmental analysis. The trap material can be thermally desorbed or desorbed wifii a solvent. The thermal method is preferred, but is not always possible. The choice of trapping or sorbent materials depends on fire application arson typically requires charcoal or charcoal combinations. 

Although it is sometimes regarded as a universal sorbent, Tenax is not suitable for every application, and many analysts choose to augment or replace it with other sorbent materials (9). In an effort to extend the purge-and-trap technique, the U.S. Environmental Protection Agency (EPA) has devised additional traps, which use Tenax as the primary sorbent backed by other, more retentive sorbents. To concentrate on a wide range of volatiles, such as in EPA method 502.2, which... 

In this method volatile organic matter in seawater is concentrated on a Tenax GC solid adsorbent trap and dry-ice trap in series. The trapped organic material is then desorbed and oxidised to carbon dioxide, which is measured with a non-dispersive infrared analyser. A dynamic headspace method was used for the extraction with the assistance of nitrogen purging. Dynamic headspace analysis [184] is an efficient extraction procedure. The efficiency of extraction... 

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