Abstract
For the analysis of low concentrations of micropollutants in environmental water samples, efficient sample enrichment and cleanup are necessary to reduce matrix effects and to reach low detection limits. For analytes of low and medium polarity, solid-phase extraction is used, but robust methods for the preconcentration of highly polar or ionizable analytes are scarce. In this work, field-step electrophoresis (FSE) was developed as an environmental sample cleanup technique for ionizable micropollutants and ionic transformation products. The FSE electrolyte system preconcentrated 15 acidic model analytes (pKa from −2.2 to 9.1) present in aqueous samples in two fractions by factors of 5–10. Simultaneously, highly mobile matrix compounds were removed including inorganic ions such as sulfate and chloride. The fractions were either directly injected for downstream analysis by reversed-phase liquid chromatography (RPLC) or further processed by evaporative preconcentration with subsequent reconstitution in an organic solvent suitable for separation methods like hydrophilic interaction chromatography. The FSE/RPLC-MS method exhibited high quantitative precision with RSDs of 3–6%. The method was successfully applied to a spiked river water sample and its performance compared with common solid-phase extraction and evaporative concentration, demonstrating a high analyte coverage. FSE combined with non-target screening by RPLC-MS revealed a strong reduction in matrix load especially at low retention times. Seventeen compounds were identified in the FSE fractions sampled at the field step boundary by retention time, accurate mass, and mass fragments. Suspect screening by FSE/RPLC-MS was facilitated by FSE’s selectivity for anionic compounds.
Highlights
The pollution of surface waters by industrial waste, pharmaceuticals, and household chemicals requires extensive monitoring and sufficient analytical workflows to control governmental regulations and identify new risks
As a first step (Exp. 1, see Fig. 1), the compatibility of field-step electrophoresis (FSE) fractionation with downstream reversed-phase liquid chromatography (RPLC)-MS and HILICMS was investigated using the river water sample N1 spiked with model analytes (10, 250, and 10,000 ng/l)
The performance of FSE sample pretreatment was evaluated in a second set of experiments (Exp. 2, see Fig. 1) by comparison with common solid-phase extraction (SPE) and evaporative concentration (EC) sample preparation using the spiked river water sample N2
Summary
The pollution of surface waters by industrial waste, pharmaceuticals, and household chemicals requires extensive monitoring and sufficient analytical workflows to control governmental regulations and identify new risks. Zweckverband Landeswasserversorgung, Langenau, Germany 4 Present Address: Bayerisches Landesamt für Umwelt, Augsburg, Germany at trace levels (ng/l to μg/l range), even modern analytical instruments often do not reach the required limits of detection (LODs). Different methods of sample enrichment were developed to increase the analyte concentration and/or reduce matrix interferences [1,2,3,4]. We compiled a list of 455 compounds previously detected in water and biota analysis from various research articles [7]. Among these compounds, 60% of the analytes were charged at pH 10, with 96% of them possessing a charge number ≤ −0.5 (values were simulated by Chemicalize provided by ChemAxon (11/02/2021)).
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
