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Simulation of the breakthrough behavior of volatile organic compounds against sorbent tube sampler as a function of concentration level and sampling volume

2014; Elsevier BV; Volume: 835; Linguagem: Inglês

10.1016/j.aca.2014.05.042

1873-4324

Ki‐Hyun Kim, Min-Hee Lee, Jan E. Szulejko,

Analytical chemistry methods development

The breakthrough (BT) properties of Tenax TA sorbent were challenged by gaseous standards containing a suite of 13 volatile organic compounds (VOC): (1) aromatic hydrocarbons: benzene (B), toluene (T), p-xylene (p-X), and styrene (S), (2) aldehydes: acetaldehyde (AA), propionaldehyde (PA), butyraldehyde (BA), isovaleraldehyde (IA), and valeraldehyde (VA), (3) ketones: methyl ethyl ketone (MEK) and methyl isobutyl ketone (MIBK), and (4) two others: isobutyl alcohol (i-BuAl) and butyl acetate (BuAc). To this end, 1–3 L of standards (10–50 ppb) were loaded on the two sorbent tubes (ST) connected in series at 100 mL min−1. The front ST-1 was used for calibration purposes, while the ST-2 for breakthrough (recovery criterion of CO entity (aldehydes, ester, and ketones). As such, BT is essentially concentration independent and relatively predictable across different functional groups and between the homologues. However, the BT behavior of ppb level VOCs is no longer consistent for certain species (like benzene or MEK) relative their ppm counterparts. This variation is explained by the Langmuir equation in which the 1/BTV is proportional to analyte gas-phase concentration, if the gas-phase/sorbent partition coefficient is large.