Determination of anionic and nonionic surfactants, their degradation products, and endocrine-disrupting compounds in sewage sludge by liquid chromatography/mass spectrometry.

Abstract

A comprehensive analytical method based on reversed-phase liquid chromatography and mass spectrometry using both atmospheric pressure chemical ionization and electrospray ionization has been developed for the simultaneous determination of anionic and nonionic surfactants, their polar degradation products, and endocrine-disrupting compounds (EDCs) in sewage sludge. Extraction of target compounds, with recovery rates from 86% to nearly 100% for polyethoxylates and from 84 to 94% for polar degradation products, was achieved applying ultrasonic solvent extraction with a mixture of methanol/ dichloromethane (7:3, v/v). Cleanup of sample extracts was performed on octadecyl solid-phase extraction cartridges. Determination of less polar compounds: alcohol ethoxylates (AEOs), nonylphenol ethoxylates (NPEOs), coconut diethanol amides, poly(ethylene glycol)s, and phthalate esters was accomplished by reversed-phase LC-APCI-MS in positive ionization mode, while more polar compounds: nonylphenolcarboxylates, nonylphenol (NP), octylphenol, and bisphenol Awere analyzed by ion-pair LC-ESI-MS under negative ionization conditions. This protocol was successfully applied to the trace determination of anionic and nonionic surfactants, polar degradation products, and EDCs in sewage sludge collected from different sewage treatment plants. The analysis revealed the presence of NP at high concentration levels ranging from 25 to 600 mg/kg. Polyethoxylates (AEOs and NPEOs) were also found in all samples at parts-per-million levels (10-190 mg/kg AEOs and 2-135 mg/kg NPEOs, respectively).