Evaluation of smartphone swabs as a toxicological analysis matrix: A controlled study in hospitalized patients

Invasive sampling limits the scope of psychoactive drug and toxic substance detection. Latent papillary trace (LPT) analysis offers a non-invasive alternative matrix, but controlled data are lacking. This study aimed to assess the performance of smartphone swab (SS) analysis as a toxicological screening tool in hospitalized patients with known medication regimens. A prospective study was conducted on adult patients from the forensic medicine and psychiatry departments of Grenoble Alpes University Hospital. SS and routine blood samples were collected and analyzed for the screening of 349 drugs using UPLC-MS/MS. Hospital records provided prescribed medications. A contamination on laboratory volunteers' smartphones tested the persistence of 11 drugs after handling. Twenty-one patients (aged 18-76, 67 % female) were included. A perfect match between detected molecules was observed between SS and blood in 24 % of cases, and between SS and recorded treatments in 14 % of cases. Of the drugs identified, 54 % were present both on the SS and in the blood, mainly benzodiazepines, opioid analgesics and selective serotonin reuptake inhibitors antidepressants. Some drugs were exclusively detected in blood (e.g., antihypertensives), while others appeared on SS but not in blood or treatment records. The contamination study showed persistence of 10/11 drugs on smartphones for up to three weeks. SS represents an innovative approach for screening specific drug classes but faces limitations due to environmental contamination, prior exposure, and the non-detection of certain substances present in blood. Cautious interpretation and further research are crucial to establish SS as a reliable toxicological tool.