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.