Passive dosing to determine the speciation of hydrophobic organic chemicals in aqueous samples.
A new analytical approach to determine the speciation of hydrophobic organic analytes is presented. The freely dissolved concentration in a sample is controlled by passive dosing from silicone (poly(dimethylsiloxane)), and the total sample concentration at equilibrium is measured. The free fraction is determined as the ratio between measured concentrations in pure water and sample. (14)C-labeled fluoranthene served as model analyte, and total sample concentrations were easily measured by liquid scintillation counting. The method was applied to surface water, stormwater runoff, and wastewater. In the untreated wastewater, 61% of the fluoranthene was bound to suspended solids, 28% was associated to dissolved organic matter, and 11% was freely dissolved, while in treated wastewater, the speciation was 16% bound to suspended solids, 4% bound to dissolved organic matter, and 80% freely dissolved. The free fraction in roof runoff (85%) and surface water (91%) was markedly higher than in runoff from paved areas, which ranged from 27 to 36%. A log K(DOC) value of 5.26 was determined for Aldrich humic acid, which agrees well with reported values obtained by fluorescence quenching and solid phase microextraction (SPME). This analytical approach combines simplicity with high precision, and it does not require any phase separation steps.
Birch
Heidi
H
Department of Environmental Chemistry and Microbiology, National Environmental Research Institute, Aarhus University, Frederiksborgvej 399, 4000 Roskilde, Denmark.
Gouliarmou
Varvara
V
Lützhøft
Hans-Christian Holten
HC
Mikkelsen
Peter Steen
PS
Mayer
Philipp
P
D002250:Carbon Radioisotopes; D005449:Fluorenes / Q000032:analysis* / Q000302:isolation & purification; D057927:Hydrophobic and Hydrophilic Interactions; D012828:Silicones / Q000737:chemistry; D052617:Solid Phase Microextraction / Q000379:methods*; D014867:Water / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000032:analysis* / Q000302:isolation & purification
D002250:Carbon Radioisotopes; D005449:Fluorenes; D012828:Silicones; D014874:Water Pollutants, Chemical; D014867:Water; C007738:fluoranthene