A diverse paper sensor for the rapid determination of nicotine and cotinine traces in air, vaping liquid, and human saliva

The smoking of nicotine and passive exposure to environmental tobacco smoke can lead to many chronic medical conditions such as respiratory, cardiovascular, and cancer diseases. Nicotine smoking can also cause complications for patients undergoing medical procedures. The prevalence of vaping among young people has added a significant challenge to the health care systems as many commercial vaping oils contain undeclared nicotine content, thus leading to nicotine addiction. Governments around the world criminalised the undeclared presence of nicotine in vaping oils. Therefore, there a is strong demand for new materials and sensors that can rapidly detect nicotine/tobacco smoke in vaping products and the environment. Similarly, there is an ongoing need for rapid methods to determine the concentration of the nicotine metabolite, cotinine, in patients prior to medical procedures. To address these needs, we have synthesised and utilised a cost-effective paper sensor for the rapid screening of nicotine and cotinine in vaping the oil, the gas phase, and the human saliva by surface-enhanced Raman spectroscopy (SERS). The new sensor can detect ultra traces of nicotine and cotinine down to 1 pg/mL and 1 ng/mL respectively, within 20 min. The new sensor can be recycled for repeated screening of nicotine and its metabolite, thus maximizing its economic viability. The was successfully utilised for the detection of nicotine in tobacco smoke and in spiked human saliva by a handheld Raman spectrometer, thus indicating its potential for real-life applications.