Determination of bisphenols A and F and their diglycidyl ethers in wastewater and river water by coacervative extraction and liquid chromatography-fluorimetry (postprint)

A simple, rapid and sensitive analytical method was developed for the simultaneous determination of
bisphenol A (BPA), bisphenol F (BPF) and their corresponding diglycidyl ethers (BADGE and BFDGE) in
wastewater and river water, in order to have a useful tool for evaluating their fate and distribution in
aquatic environments. It was based on their extraction with coacervates made up of decanoic acid reverse
micelles and subsequent determination by liquid chromatography/fluorimetry. The procedure involved the
extraction of 10.8 mL of water sample for 5 min, its centrifugation for 10 min to accelerate phase
separation and then the chromatographic analysis of the target compounds. Clean-up or solvent
evaporation steps were not necessary to get the required sensitivity and selectivity. Extraction efficiencies
and concentration factors mainly depended on the amount of decanoic acid and tetrahydrofuran making
up the coacervate. A general equation for the prediction of the volume of the coacervate as a function of
its components has been proposed and fitted by nonlinear regression. This equation permits to know a
priori the maximum concentration factors that can be achieved under given experimental conditions.
Extractions were independent of salt addition (up to 1M), the temperature (up to 60 ºC) and the pH (below
4) rendering the method robust. Recoveries in samples ranged between 80 and 96% and the actual
concentrations factors were between 87 and 102, which resulted in practical detection limits around 30-32
ng L-1. The method was successfully applied to the determination of the target pollutants in raw and
treated sewage from four mechanical-biological treatment plants and three rivers. Bisphenols and their
diglycidyl ethers were present in wastewater influents at concentrations in the range 0.96 to 1.6 g L-1.
The biological treatment at the WWTPs studied reduced the concentration of BPA and BPF in a
percentage above 75%, while diglycidyl ethers were not detected in most of the effluents investigated.
Only BPA was detected in surface waters and its concentration was above the general limit recommended
by the EU for organic pollutants in waters.