“…A total of 24 studies from 11 countries were included (Germany (n=3 studies), Australia (n=1), Belgium (n=3), Canada (n=6), the USA (n=2), France (n=2), Japan (n=3), the Netherlands (n=2), the UK (n=1), Sweden (n=2), Switzerland (n=1)) (online supplementary appendix 1). 4 5 10–31 Sampling was done by wiping the containers (n=20) or by immersion (n=3). Liquid chromatography tandem-mass spectrometry (n=15) and gas chromatography tandem-mass spectrometry (n=15) were mostly used to quantify the drugs.…”