Postmortem nasal swab screening for cocaine: Preliminary evidence for early toxicological orientation in forensic autopsy practice.

Early toxicological information may be useful during death scene investigation and early autopsy, when decisions regarding sampling, ancillary analyses and investigative priorities must be made before conventional laboratory results are available. This preliminary study evaluated the analytical feasibility of nasal swab testing for postmortem cocaine screening and early toxicological orientation. Nasal swabs were collected during 104 autopsies, extracted in phosphate buffer and analyzed using a rapid immunochemical screening test for cocaine metabolites. Each extract was tested in triplicate. All nasal swab extracts, regardless of screening result, were subsequently analyzed by LC-MS/MS for cocaine, benzoylecgonine, norcocaine and cocaethylene. Femoral blood was analyzed by LC-MS/MS, whereas urine was analyzed by immunochemical screening, with presumptive-positive samples subsequently confirmed by LC-MS/MS for cocaine and its metabolites. Urine screening was presumptive-positive in 25 cases, all of which were confirmed by LC-MS/MS. Nasal swab screening was presumptive-positive in 22 cases and negative in 82. LC-MS/MS confirmed cocaine and/or metabolites in all 22 presumptive-positive nasal swab extracts, whereas all 82 screening-negative extracts were negative by LC-MS/MS. Three urine-confirmed positive cases were negative in femoral blood and nasal swab extracts. Norcocaine was detected in all LC-MS/MS-positive nasal swab extracts, whereas cocaethylene was detected in six cases and in the corresponding femoral blood and urine samples. The detection of benzoylecgonine, norcocaine and cocaethylene increased the analytical and interpretive value of nasal swab findings beyond parent cocaine alone. These results support prospective studies to determine whether rapid nasal swab screening can contribute to early postmortem toxicological orientation in forensic practice.