Fingerprints: A New Specimen for Innovative Applications for the Detection of Xenobiotics

Fingerprints are invisible traces that result from a deposition of sweat and sebum present on the papillary ridges. As sweat and sebum contain drugs, fingerprints are promising since collection is rapid, non-invasive and difficult to falsify. Very limited data are available in the literature, and therefore, it seems opportune to study the transfer of xenobiotics onto the items taken in hand via the fingerprints. Two studies were implemented using the ballpoint pen as a model. The objective of the first study was to compare the nicotine concentrations found on the pens of three smokers and three non-smokers. Five pens, belonging to each subject and used regularly, were rubbed with a cotton swab dipped in methanol and analyzed by liquid chromatography coupled with tandem mass spectrometry (LC-MS-MS). The second study was to analyze the transfer via fingerprints of four volunteers, after administration of 30 mg of codeine. The objective was to determine the feasibility of this study and the time corresponding to the highest concentration of codeine. Over a 24-h period, new pens were handled for 5 min by the four volunteers, rubbed with a cotton swab dipped in methanol, and then analyzed by LC-MS-MS. The nicotine study showed a major difference between the nicotine concentrations obtained from smokers (between 6 and 276 ng/pen) and non-smokers (between 2 and 4 ng/pen). After administration of 30 mg of codeine, the analysis of the pens of the four volunteers allowed to demonstrate the presence of codeine up to 24 h between 9 and 544 pg/pen. Normal hygiene practices did not influence the final result. The highest concentration was observed after 2 h. Morphine was also detected (between 19 and 33 pg/pen). These preliminary results should be considered a demonstration of the interest of fingerprints testing to document drug exposure.