TY - JOUR
T1 - Measuring binding and speciation of hydrophobic organic chemicals at controlled freely dissolved concentrations and without phase separation
AU - Gouliarmou, Varvara
AU - Smith, Kilian E.C.
AU - Wollesen de Jonge, Lis
AU - Mayer, Philipp
PY - 2012
Y1 - 2012
N2 - The binding and speciation of hydrophobic organic chemicals (HOCs) in aqueous solutions were determined by controlling chemical activity and measuring total concentrations. Passive dosing was applied to control chemical activities of HOCs in aqueous solutions by equilibrium partitioning from a poly(dimethylsiloxane) polymer preloaded with the chemicals. The HOC concentrations in the equilibrated solutions [C-solution(eq)] and water [C-water(eq)] were then measured. Free fractions of the HOCs were determined as C-water(eq)/C-solution(eq), whereas enhanced capacities (E) of the solutions for HOCs were determined as C-solution(eq)/C-water(eq). A mixture of polycyclic aromatic hydrocarbons served as model analytes, while humic acid, sodium dodecyl sulfate, hydroxypropyl-beta-cyclodextrin, and NaCl served as model medium constituents. The enhanced capacities were plotted versus the concentrations of medium constituents, and simple linear regression provided precise partition ratios, salting out constants, and critical micelle concentrations. These parameters were generally in good agreement with published values obtained by solid phase microextraction and fluorescence quenching. The very good precision was indicated by the low relative standard errors for the partition ratios of 0.5-8%, equivalent to 0.002-0.03 log unit. This passive dosing approach allows binding and speciation of HOCs to be studied without any phase separation steps or mass balance assumptions.
AB - The binding and speciation of hydrophobic organic chemicals (HOCs) in aqueous solutions were determined by controlling chemical activity and measuring total concentrations. Passive dosing was applied to control chemical activities of HOCs in aqueous solutions by equilibrium partitioning from a poly(dimethylsiloxane) polymer preloaded with the chemicals. The HOC concentrations in the equilibrated solutions [C-solution(eq)] and water [C-water(eq)] were then measured. Free fractions of the HOCs were determined as C-water(eq)/C-solution(eq), whereas enhanced capacities (E) of the solutions for HOCs were determined as C-solution(eq)/C-water(eq). A mixture of polycyclic aromatic hydrocarbons served as model analytes, while humic acid, sodium dodecyl sulfate, hydroxypropyl-beta-cyclodextrin, and NaCl served as model medium constituents. The enhanced capacities were plotted versus the concentrations of medium constituents, and simple linear regression provided precise partition ratios, salting out constants, and critical micelle concentrations. These parameters were generally in good agreement with published values obtained by solid phase microextraction and fluorescence quenching. The very good precision was indicated by the low relative standard errors for the partition ratios of 0.5-8%, equivalent to 0.002-0.03 log unit. This passive dosing approach allows binding and speciation of HOCs to be studied without any phase separation steps or mass balance assumptions.
U2 - 10.1021/ac2028497
DO - 10.1021/ac2028497
M3 - Journal article
C2 - 22148547
SN - 0003-2700
VL - 84
SP - 1601
EP - 1608
JO - Analytical Chemistry
JF - Analytical Chemistry
IS - 3
ER -