Skip directly to search Skip directly to A to Z list Skip directly to page options Skip directly to site content

NIOSHTIC-2 Publications Search

Search Results

On-line multibed sorption trap and injector for the GC analysis of organic vapors in large-volume air samples.

Authors
Sanchez-JM; Sacks-RD
Source
Anal Chem 2003 Feb; 75(4):978-985
NIOSHTIC No.
20029241
Abstract
A capillary-dimension on-line sorption trap is used to preconcentrate organic vapors from large-volume air samples and inject the organic compounds into the separation column as a relatively narrow vapor plug. The multibed trap is made from a Co-Ni alloy for resistive heating during sample desorption and uses four different carbon-based adsorption materials that are graded from weakest to strongest in the direction of the sample gas flow during sample preconcentration. The flow direction then is reversed for sample injection. The multibed design and the flow direction reversal during thermal desorption prevents the higher-boiling-point compounds in the sample from reaching the strongest adsorbing material, from which they would be difficult to desorb as a sufficiently narrow vapor plug. A relatively high current pulse is used to rapidly achieve trap temperatures in the 200-400 degrees C temperature range, and a lower current is used to maintain the maximum temperature for several seconds in order to ensure injection of the entire trapped sample. A temperature of 350 degrees C is reached after degrees 1.5 s, and injection plug widths are typically in the range of 0.6-1.3 s. Plots of peak area versus sample collection time show excellent linearity and shot-to-shot relatively standard deviations of about +/- 5%. Performance data are presented for a mixture of 42 volatile compounds spanning a volatility range from n-C5 to n-C12. Data are presented for injection plug width and shape for both polar and nonpolar compounds. Decomposition of thermally labile compounds is observed for injection temperatures above 300 degrees C.
Keywords
Organic-vapors; Air-samples; Air-sampling; Organic-compounds; Vapors; Sampling; Sampling-methods; Temperature-control; Temperature-effects; Temperature-measurement; Alkanes; Alcohols; Gas-chromatography; Equipment-design; Organic-chemicals; Analytical-processes; Analytical-methods; Analytical-instruments
CODEN
ANCHAM
Publication Date
20030215
Document Type
Journal Article
Funding Type
Grant
Fiscal Year
2003
NTIS Accession No.
NTIS Price
Identifying No.
Grant-Number-R01-OH-003692
Issue of Publication
4
ISSN
0003-2700
Source Name
Analytical Chemistry
State
MI
Performing Organization
University of Michigan, Ann Arbor
TOP