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A comparison of porous polymers used in collecting organic volatiles in foods

Porapak Q, Chromosorb 102, and Tenax GC, three porous
polymers commonly used as adsorbents in headspace analyses were
investigated. The retention times of various low-boiling compounds
relative to water were measured on the collection columns to determine
which compounds would be lost during the water removal step
employed after sampling aqueous materials. Compounds eluted
fastest from Tenax GC precolumns and slowest from Porapak Q,
with retention times on Chromosorb 102 generally intermediate.
Thus, loss of low-boiling compounds relative to water was greatest
on Tenax GC and limited the use of this polymer for quantitative
study of samples containing low-boiling volatile compounds. The
residual water in Porapak Q precolumns employed in the usual
procedure for collection of volatile materials by entrainment from
aqueous systems, could be completely eluted in 15 min with a N₂ purge of 30 ml/min at 55°C. without appreciable loss of collected
organic compounds.
Retention times of high-boiling organic compounds were determined
on the precolumns, and those containing Tenax GC had shorter
times than Chromosorb 102 or Porapak Q. Under conditions employed
for unloading trapped compounds from precolumns, fewer compounds
remained on Tenax GC precolumns. Thus, Tenax GC appeared to be
the trapping polymer of choice in investigations involving high-boiling
compounds. Back flushing of Porapak Q, Chromosorb 102,
and Tenax GC precolumns during unloading was essential in order
to recover the trapped organics within the time allotted for unloading
at 135°C. At 280°C back flushing on Tenax GC was not necessary
to insure unloading since retention times were well within the
unloading period.
The recovery of n-undecane from the precolumns after
simulated water removal conditions was found to be 98.5% for
Tenax GC, 99.5% for Porapak Q, and 100.0% for Chromosorb 102. / Graduation date: 1976
Date01 July 1975
CreatorsBoyko, Alayne Linda
ContributorsScanlan, Richard A., 1937-
Source SetsOregon State University
Detected LanguageEnglish

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