Quantitative determination of octylphenol, nonylphenol, alkylphenol ethoxylates and alcohol ethoxylates by pressurized liquid extraction and liquid chromatography–mass spectrometry in soils treated with sewage sludges

Surfactants have one of the highest production rates of all organic chemicals. Non-ionic surfactants, especially alkylphenol ethoxylates, received most attention as precursors of estrogenic metabolic products generated during wastewater treatment. Alkylphenols (octyl and nonylphenol), alkylphenol polyethoxylates (APEOs), and alcohol ethoxylates (AEOs) have been determined in a Mediterranean forest soil (Mediterranean Rendzic Leptosol) amended with sludges from six waste water treatment plants (WWTPs) located in the Valencian Community. These compounds were isolated from soil by pressurized liquid extraction (PLE) using a mixture acetone–hexane (50:50 v/v), the extracts were cleaned up by solid-phase extraction (SPE) with C18, and determined by liquid chromatography atmospheric pressure chemical ionization-mass spectrometry (LC–APCI-MS) using analytical standards for quantification. The method enabled high-reliable identification by monitoring the corresponding ammonium adduct [M+NH3]+ for AEOs and APEOs, and the deprotonated molecule [M–H]− for octyl and nonylphenol. Recoveries, determined spiking soil samples at different concentrations, ranged from 89 to 94%, with limits of quantification from 1 to 100 μg kg−1. Data obtained from a soil sample mixed with biosolids in the laboratory showed that these compounds are present at concentrations ranging from 0.02 to 5 mg kg−1. According to these concentrations, levels of possible risk can be concluded for the presence of nonionic surfactants in soil. However, further assessment will be necessary to establish the relationship between exposure and effect findings.