A guidance for the enrichment of micropollutants from wastewater by solid-phase extraction before bioanalytical assessment

Background

Wastewater can contain a complex mixture of organic micropollutants, with both chemical analysis and effect-based methods needed to identify relevant micropollutants and detect mixture effects. Solid-phase extraction (SPE) is commonly used to enrich micropollutants prior to analysis. While the recovery and stability of individual micropollutants by SPE has been well studied, few studies have optimized SPE for effect-based methods. The aim of the current study was to develop and evaluate two standard operating procedures (SOPs) for the enrichment of micropollutants in preparation for chemical analysis and bioanalysis, one covering a broad range of chemicals and the other selective for estrogenic chemicals.

Results

Pristine surface water spiked with > 600 micropollutants was used to develop a generic extraction method for micropollutants with a wide range of physiochemical properties, while water spiked with estrogenic chemicals was used to identify a selective extraction method. Three different SPE sorbents were tested, with recoveries of individual chemicals and effect in assays indicative of mutagenicity, estrogenic activity, and fish embryo toxicity assessed. The sorbent HRX at pH 7 was selected for the generic extraction method as it showed the best recovery of both individual chemicals and effect in the bioassays. The sorbent HLB at pH 3 showed optimal recovery of estrogenic chemicals and estrogenic activity. The two optimal SPE methods were applied to spiked and unspiked wastewater effluents, with the concentrations of detected chemicals and observed effects similar to those of previous studies. The long-term storage of both extracts and SPE cartridges for estrogens and estrogenic activity after extraction with the HRX and HLB methods were evaluated, with estrogenic effectiveness close to 100% after 112 days when HLB was used.

Conclusions

HRX is recommended for generic extraction, while HLB is optimal for the selective extraction of estrogenic micropollutants. However, if a laboratory only wants to use a single SPE sorbent, HLB can be used for both generic and selective extraction as it yielded similar chemical and effect recovery as HRX for a wide range of micropollutants. This paper is supplemented by the final SOP that includes a variant for generic extraction and one for the extraction of estrogenic chemicals.