Researchers collected 420 surface swabs over 3 weeks from bathrooms, tables, and a bar in an anonymous pub in southern England.
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Confirmatory LC-MS detected cocaine in 250 swabs and ketamine in 70; 64 swabs contained both substances.
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Direct, untargeted ASAP-MS rapidly screened swabs but mainly detected samples with relatively high cocaine levels and missed many residues found by LC-MS.
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Methanol extraction with targeted ASAP-MS increased sensitivity, but the method still missed 59.51% of cocaine-positive and 88.57% of ketamine-positive samples identified by LC-MS.
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ASAP-MS produced 15 false-positive results, including apparent ketamine signals linked to procaine, and the researchers said further optimization is needed before routine on-site screening.
