The transfer and analysis of fingerprints on manipulated objects has recently been described. Smartphones have become everyday objects on which the accumulation of fingerprints seems important. The objective of this preliminary study is to evaluate smartphones as a new matrix for drug testing.

The authors evaluated a dry swab (Deltalab Invasive sterile EUROTUBO®) to collect fingerprints on smartphone surface. A classic cotton tip was also evaluated. Each smartphone was rubbed for 20seconds on all sides. The swab extract was analyzed by qualitative toxicological screening by UPLC-MS/MS on a Xevo TQ-XS mass spectrometer comprising approximately 350 compounds with two MRM transitions. Fifteen adult volunteers agreed to swab their own smartphone and communicate their treatment. Six control swabs were also analyzed before and after hand sanitizer cleaning of the smartphone.

The following drugs have been detected on smartphones: lacosamide, zolpidem, oxomemazine, doxylamine, cannabidiol, fluoxetine, codeine, cetirizine, citalopram, fentanyl, tramadol and metabolites, metoclopramide, scopolamine, diphenydramine; atenolol, bisoprolol, ramipril, apixaban, rivaroxaban, repaglinide, clopidogrel metabolite; caffeine, cotinine, paracetamol. It was possible to identify, after a single dose, scopolamine, oxomemazine (12hours later) and prazepam (72hours later). Several drugs were not detected despite the declarations of consumption of the volunteers: dextrometorphan, pantoprazole, esomeprazole, dapagliflozin, amiodarone, furosemide, candesartan, irbesartan, amlodipine, fluindione.

These results showed that the detection of many drugs is possible on the surface of smartphones, in the context of chronic treatment and after a single dose. The study of smartphone swabs could provide a complementary matrix, in forensic toxicology or toxico-epidemiology. This new alternative matrix is promising because the sampling procedure is fast, non-invasive, and inexpensive.