Rapid detection of illicit drugs in neat saliva using desorption/ionization on porous silicon

The ability to detect illicit drugs directly in oral fluids is of major interest for roadside, workplace and athlete drug testing. For example, roadside testing for popular drugs of abuse is being rolled out by law enforcement agencies following the introduction of legislation in several countries all over the world. This paper reports on the direct analysis of methamphetamine, cocaine and 3,4-methylenedioxymethamphetamine in oral fluids using a hydrophobic porous silicon array as a combined drug extraction and concentration medium. Analysis by laser desorption/ionization time-of-flight mass spectrometry (MS) identified these drugs with a sensitivity in line with the suggested confirmatory cut-off concentrations, and 300 times faster. In addition, MS imaging demonstrated good spot-to-spot reproducibility of the signal. Our analytical approach is compatible with multiplexing and is therefore suitable for high-throughput analysis of samples obtained from drug testing in the field. Furthermore, the application of this analytical technology is not limited to illicit drugs or oral fluids. Indeed, we believe that this platform technology could be applied to the high-throughput analysis of diverse metabolites in body fluids. ► Fluorinated pSi surfaces were used to effectively extract illicit drugs from water and neat saliva. ► We demonstrate quantitation of illicit drugs in both water and saliva using desorption ionization on porous silicon (DIOS). ► Crystallization patterns were examined using DIOS imaging to confirm spot-to-spot reproducibility.