Suspect screening and quantification of trace organic explosives in wastewater using solid phase extraction and liquid chromatography-high resolution accurate mass spectrometry

- 34 sorbents tested for SPE of multiple classes of trace explosives.
- Recoveries between 56 and 124% achieved using mixed polarity polymeric sorbents.
- Determination of 29 explosives possible at the ng-μg L−1 level in wastewater matrix.
- 2,4-dinitrotoluene detected in London composite wastewater samples (≤303 ng L−1).
- Both suspect screening and quantitative analysis possible with LC-HRMS.

The first comprehensive assessment of 34 solid phase extraction sorbents is presented for organic explosive residues in wastewater prior to analysis with liquid chromatography-high resolution accurate mass spectrometry (LC-HRMS). A total of 18 explosives were selected including nitramines, nitrate esters, nitroaromatics and organic peroxides. Three polymeric divinylbenzene-based sorbents were found to be most suitable and one co-polymerised with n-vinyl pyrrolidone offered satisfactory recoveries for 14 compounds in fortified wastewater (77-124%). Limits of detection in matrix ranged from 0.026-23 μg L−1 with R2 ≥ 0.98 for most compounds. The method was applied to eight 24-h composite wastewater samples from a London wastewater works and one compound, 2,4-dinitrotoluene, was determined over five days between 332 and 468 g day−1 (225-303 ng L−1). To further exploit the suspect screening capability, 17 additional explosives, precursors and transformation products were screened in spiked wastewater samples. Of these, 14 were detected with recoveries from 62 to 92%, highlighting the broad applicability of the method. To our knowledge, this represents the first screen of explosives-related compounds in wastewater from a major European city. This method also allows post-analysis detection of new or emerging compounds using full-scan HRMS datasets to potentially identify and locate illegal manufacture of explosives via wastewater analysis.

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