Tetraethoxysilane/Polydopamine-Functionalized Composite Materials to Assemble a Sampling Device for Monitoring Amphetamines in Exhaled Breath

Exhaled breath aerosol (EBA) as a potential sample has the advantages of noninvasive, simple, rapid, and unrestricted sampling in monitoring illicit abuse drugs. However, the extremely low level of drugs in EBA makes it difficult to directly determine by existing methods. In this study, tetraethoxysilane/polydopamine functionalized polypropylene (TPP) materials were prepared and assembled into a self-designed portable sampling device to achieve enrichment of amphetamines (AMPs) in simulated EBA. By means of high-performance liquid chromatography coupled with triple quadrupole tandem mass spectrometry (HPLC-TQ-MS/MS) detection, the adsorption performance of TPP materials was investigated and further optimized from aqueous solution to simulated EBA. After optimization of combining TPP film with TPP cotton, the combination of three-layer cotton plus one-layer film could reach the adsorption rates of 82.56 ± 1.42% to 94.24 ± 1.68% for AMPs, thus HPLC-TQ-MS/MS detection limits for AMPs could be as low as 1.7–9.3 pg/filter and the recoveries ranged from 82.60% to 91.89% with relative standard deviations of 0.24–7.64% and 2.23–9.10%, respectively. By this way, the prepared materials assembled to the sampling device were successfully validated by HPLC-TQ-MS/MS detection of ephedrine (EPH) in EBA of 6 volunteers after taking tablets. Their EPH contents were between 59.5 ± 81.3 and 1671.0 ± 85.3 pg/filter, suggesting a good correlation with that in saliva. These results proved that the prepared materials could be applied in enrichment of AMPs in EBA prior to HPLC-TQ-MS/MS analysis, facilitating the improvement of the on-site EBA sampling and rapid monitoring of illicit abuse drugs.