6. Conclusion
Selection of the appropriate GC column to separate very polar
volatile compounds in aqueous samples by their injection directly
into GC is a difficult task. The serial connection of two columns,
one with a polar (polyethylene glycol) and the other with a nonpolar
(dimethylpolisiloxane) stationary phase, proved to be a good
separation system for SCFAs in water of not very complex matrix.
Generally the sample must be centrifuged before injection to
separate particulate matter off. The detection limit was not higher
than 0.25 mg L−1 and no acids were detected in treated municipal
water. In landfill leachate, C2-C5 acids were determined at the
levels depending strongly on the acid: ethanoic and propanoic acid
were found to be present at a concentration of about 15 mg L−1 and
at 4.5 mg L−1, respectively. The remaining acids were at much lower
concentrations.