Assessing the potential of metal oxide semiconducting gas sensors for illicit drug detection markers

Port security with a focus on drug trafficking prevention requires inexpensive and portable systems for on-site analysis of containers in order to minimise transit delays. The potential of metal oxide semiconductors for illicit drug detection is explored here. A six-sensor array consisting of WO3 and SnO2 inks was devised. Zeolites H-Y and H-ZSM-5 were incorporated to introduce variations in sensor response. Sensors were tested against acetone, ethanol and toluene as proxies for their use in illicit drug manufacture and against ammonia and nitrogen dioxide as first models of amino- and nitro-containing compounds, given their prevalence in the structural framework of drugs and precursor molecules. Sensor sensitivity and selectivity were greatly enhanced by inclusion of zeolite materials. Admixed sensing materials were found to be particularly sensitive to the gases. Support vector machines were applied to the dataset as classification tools that accurately classified the data according to gas type. The sensing array was successful in targeting and discerning between the tested drug markers. This could be key for illicit drug detection with electronic noses based on MOS technology in the future.