brief, 0.05–0.2 g of a sorbent was placed in a 2.0 mL HPLC glass vial
fitted with a Teflon-lined screw cap. An aqueous solution (1.0 mL)
containing a chemical, 200 mg L1 of NaN3 as a biocide and 0.01 M
CaCl2 was added to the vial. Aqueous solutions of chemicals were
prepared by using a stock solution in acetone such that the acetone
concentration in aqueous solutions did not exceed 0.7%. Then, by
evaporating acetone from aqueous solutions at room temperature,
its concentration was reduced to that less than 0.01% (as confirmed
spectrophotometrically by means of Genesys 10UV, Thermo
Scientific). The losses of simazine and diuron from aqueous solutions,
due to their assumed volatilization, during acetone evaporation
were negligible (if any) which was verified by analyzing final
concentrations of compounds in aqueous solutions (as described in
Section 2.4).