Strategies for selecting optimal sampling and work-up procedures for analyzing alkylphenol polyethoxylates in effluents from non-activated sludge biofilm reactors

Trace-level analysis of alkylphenol polyethoxylates (APEOs) in wastewater containing sludge requires the prior removal of contaminants and preconcentration. In this study, the effects of the types of alkylphenols present, their degree of ethoxylation, the biofilm-wastewater treatment and sample matrix were investigated on optimal work-up procedures for these purposes. The spot for sampling APEO-containing specimens from an industrial wastewater treatment plant was optimized, and boxed round the tubing carrying the wastewater to prevent sedimented sludge contaminating the collected samples. Following these changes, the sampling precision (in terms of dry matter content) at a point just under the tubing leading from the biofilm reactors was 0.7 % RSD. The findings were applied to develop a work-up procedure for use prior to a high-performance liquid chromatography-fluorescence detection analysis method capable of quantifying nonylphenol polyethoxylates (NPEOs) and poorly investigated dinonylphenol polyethox...