Analysis of alkyl nitrates and selected halocarbons in the ambient atmosphere using a charcoal preconcentration technique

Abstract

A method has been developed to measure >C3 alkyl nitrates and C!-C2 halocarbons, such as perchloroethylene and bromoform, in ambient air. The method preconcentrates analytes on a 5-mg charcoal trap from multiliter volumes of air. Analytes are desorbed from the charcoal with a small volume of solvent and are analyzed by highresolution gas chromatography with electron capture detection. Laboratory and field tests have been performed to evaluate method precision, analyte breakthrough, and compound recovery from the charcoal. Tests verified that the sampling/analytical system is free from artifact formation under clean to moderately polluted conditions, but further tests are required for areas of high concentrations of hydrocarbons, NO*, and oxidants. The method allows measurement of halocarbons and >C3 alkyl nitrates at concentrations in the pptv range.

Levels and pattern of alkyl nitrates, multifunctional alkyl nitrates, and halocarbons in the air over the Atlantic Ocean

“…[ Atlas and Schauffier, 1991] reported the alkyl nitrate formation on charcoal when spiking the enriched air prior to sampling with high concentrations of hydrocarbons (C5 and C6, ppmv range). They concluded, however, that under "normal" conditions, artifact formation is not a significant problem.…”

Methods, fluxes and sources of gas phase alkyl nitrates in the coastal air

“…Atlas and Schauffler 1991). A critical parameter to be considered is the breakthrough volume of the gas adsorption system.…”

“…Sampling of gas phase ANs in air has been performed in several ways, using Tenax adsorption columns Fischer et al 2000Fischer et al , 2002, a combination of Tenax cartridges and polyurethane (PU) foam , silicagel and PU foam (Luxenhofer et al 1996), silicagel and Tenax (Schneider et al 1998;Schneider and Ballschmiter 1999) or even charcoal (Atlas and Schauffler 1991;De Kock and Anderson 1994). Simpson et al (2006) preconcentrated trace gases from air samples by passing 1.5 L of canister air through a stainless steel tube filled with 1/8-in diameter glass beads and immersed in liquid nitrogen.…”

Preparing to Measure the Effects of the NOxSIP Call— Methods for Ambient Air Monitoring of NO, NO2, NOy, and Individual NOzSpecies

“…Different preconcentrators are used, including charcoal traps, 62 Tenax, 63,64 or cryogenically cooled glass beads. 65 Hao et al 66 describe the use of post-column thermal decomposition for a variety of nitrates to NO 2 followed by luminol chemiluminescence-based detection.…”