Low ppt residue monitoring of persistent organic pollutants in groundwater samples using direct immersion solid phase micro extraction arrow (DI-SPME) with gas chromatography-mass spectrometry

A novel analytical method based on direct immersion solid-phase microextraction using SPME Arrow coupled to gas chromatography–mass spectrometry (DI-SPME-GC–MS) was developed and validated for the trace-level determination of 15 persistent organic pollutants (POPs) in groundwater samples. The method enabled sub-ng L −1 quantification without the need for solvent extraction or derivatization. Key experimental parameters were optimized using univariate regression models, revealing that extraction time and speed had the strongest impact on enrichment efficiency. The method achieved limits of quantification ranging from 1.28 to 3.56 ng L −1 , with R 2 values >0.994 for all compounds and recoveries between 93 % and 102 %. Matrix effects were evaluated in both ultrapure and groundwater matrices, with satisfactory robustness under environmental conditions. Practical limitations related to fiber degradation at high salt levels and compatibility only with aqueous media were also recorded. The proposed method offers a simple, solvent-free and sensitive alternative for routine monitoring of legacy pesticides in environmental waters. • DI-SPME Arrow–GC–MS/MS enables ppt-level POPs detection in groundwater. • Validated under SANTE guidelines. • Low-level identification of POPs achieved for groundwater monitoring. • NaCl optimization (5 %) enhanced reproducibility via salting-out effect. • Applied to nationwide POPs groundwater monitoring study in Greece.