Cork-Activated Carbon as a Sorptive Phase for Microextraction of Emerging Contaminants in Water Samples

A novel strategy for microextraction of emerging contaminants was developed by using cork activated carbon (CAC) as the sorbent phase. Carbonization of the natural phase increased the surface area and the porosity of the material, thus improving the extraction efficiency. Moderately polar compounds, such as ibuprofen and its metabolites, were used as model analytes in water samples. Rotating disk sorptive extraction (RDSE) together with gas chromatography‒mass spectrometry (GC‒MS) were used for extraction and determination of the analytes, respectively. The optimum conditions for the material synthesis were 600 °C, K2CO3 as the activating agent and a mass ratio of 0.8:1 (activating agent:raw material). The optimum values for the RDSE were pH 2, a sample volume of 25 mL and an extraction time of 90 min. The absolute recovery rates for ibuprofen and its metabolites ranged from 19 to 55%, and the relative standard deviations were between 3 and 13%. The proposed method was used to measure the analytes in the influent and effluent from a wastewater treatment plant in Santiago, Chile. The concentrations found for ibuprofen and its metabolites were 0.98–9.8 µg L-1 and 0.8–8.6 µg L-1 in the influent and effluent, respectively. Activation of the cork material enabled the synthesis of a sorbent phase with sorption efficiencies similar to those obtained with the commercial octadecylsilane (C18) phase and superior to that observed for styrene-divinylbenzene (S-DVB). This process is simple and cost-effective.