ZICcHILIC-HRMS as a complementary approach to IC-HRMS for highly polar contaminants in water: a method-specific assessment.

Highly polar contaminants are analytically challenging due to the substantial differences in their chromatographic retention and ionisation behaviour between compound groups. This communication evaluates a developed and validated ZICcHILIC-HRMS workflow as a complementary approach to an established anion IC-HRMS method for analysing selected highly polar contaminants in water. The study focuses on implementing polarity switching, comparing method-specific analyte coverage and deriving practical method-selection criteria. Polarity switching enabled the acquisition of both positively and negatively ionising compounds within a single ZICcHILIC-HRMS run, thereby improving the practical efficiency of the comparatively lengthy chromatographic workflow. A comparison with IC-HRMS revealed partially overlapping, yet distinct, analytical coverage. IC-HRMS remained advantageous for small, strongly polar anionic compounds due to direct injection, lower quantification limits, shorter runtime and higher routine robustness. In contrast, ZICcHILIC-HRMS extends the accessible analyte spectrum to compounds outside the scope of the applied anion IC-HRMS and to analytes that can be detected in positive electrospray ionisation mode. These findings support the use of ZICcHILIC-HRMS as a complementary, LC-HRMS-compatible tool for the exploratory monitoring of highly polar contaminants in water, particularly when both ionisation modes and conventional HPLC-HRMS instrumentation are to be employed.