Optimisation and calibration of a novel passive sampler based on diffusion gradient in thin films
for polar organic compounds (o-DGT)

^1Jakub Urík; ^1Jitka Bečanová; ^1Pavlína Karásková; ^1Kateřina Švecová; ^1Foppe Smedes,
^1Branislav Vrana

Research Centre for Toxic Compounds in the Environment; Kamenice 753/5; 625 00 Brno; Czech Republic

urik@recetox.muni.cz


Passive samplers are useful tools for sampling of trace pollutants in the environment. However,
concentrations of polar organic compounds in waters acquired by currently mostly used passive
samplers such as POCIS are semiquantitative, due to a strong dependence of uptake rates on the
variable hydrodynamic conditions and/or sorption of analytes to the membrane material separating
the sorbent from the aqueous phase. Sampling rates acquired by laboratory calibrations may
therefore differ from the actual sampling rates in the field. Application of a thin diffusion layer
of hydrogel, which behaves as an immobilized water layer on top of the sampling surface, may help
to control the analyte uptake rate, eliminating the effect of hydronamic conditons. Recently, a
promising sampler design has been proposed (Chen et al. 2012), which is based on DGT sampler
commonly used for sampling of metals in waters. The sampler consists of agarose hydrogel layer with
dispersed sorbent and a diffusion layer of pure agarose hydrogel. For accurate calibration,
diffusion coefficients of the compounds in hydrogel are required. These were obtained by measuring
the migration of the compounds in a stack of several hydrogel layers (Rusina et al. 2010). Then,
laboratory calibration experiments were conducted in an artificial flow-through system with two
different water flow rates and different hydrogel thicknesses for several groups of emerging
pollutants, including perfluorinated compounds and pharmaceuticals. As expected, using a diffusive
layer greatly reduced sampling rates for most of the compounds. However, increasing flow velocity
still resulted in increased sampling rates. These results show that further research is needed in
order to evaluate the effect of hydrodynamic conditions. Due to low sampling rates, it is
recommended to use a sampler design with larger sampling area for future experiments.



References


Chen C.-E., Zhang H., and Jones K. C., A novel passive water sampler for in situ sampling of
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J. Environ. Monit., 2012, 14, 1523–30.

Rusina T. P., Smedes F., and Klánová J., Diffusion Coefficients of Polychlorinated Biphenyls and
Polycyclic Aromatic Hydrocarbons in Polydimethylsiloxane and Low-Density Polyethylene Polymers., J.
Appl. Polym. Sci., 2010, 116(3), 1803–1810



Acknowledgments


The project (TB030MZP001/EMERTOX) received financial support from the Technology Agency of the
Czech Republic (TACR). The RECETOX research infrastructure was supported by the projects of the
Czech Ministry of Education (LO1214) and (LM2011028)