Trace analysis of biocidal oligoguanidines in environmental water samples

•Optimization of solid-phase extraction for biocidal oligoguanidines from water samples.•Quantitation by liquid chromatography hyphenated with mass spectrometry.•Detection limits in the sub-μg L−1 range allow residue analysis in the environment.•Selection of appropriate markers for complex mixtures of oligoguanidines.

This paper demonstrates the determination of residues of biocidal oligoguanidines manufactured by polycondensation of guanidine hydrochloride and 2,2′-(ethylenedioxy)bis(ethylamine) in environmental water samples. The analytes were preconcentrated from samples adjusted to pH 4 by solid-phase extraction using a mixed-mode sorbent with weak cation exchange functionalities. Elution from the sorbent was achieved by 2 M hydrochloric acid in methanol. After evaporation and reconstitution in water, the extract was analyzed by reversed-phase high performance liquid chromatography combined with quadrupole/time-of-flight or triple quadrupole mass spectrometry employing electrospray ionization. A preconcentration factor of 10,000 could be achieved and detection limits were in the sub-μg L−1 range. This method looks promising to monitor the fate of these biocides released into the aquatic environment during different applications.