Postmortem oral fluid toxicology testing

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The collection process is performed by placing a cellulose collection pad into the sublingual area, adjacent to the second bicuspid and first molar, for approximately 15 minutes. The collection pad is then removed, observed for pad saturation (a minimum of 1 mL is required), placed into the collection device, and shipped to the laboratory. Analysis is performed using an enzyme-linked immunosorbent assay (ELISA) and/or liquid chromatography-mass spectrometry/mass spectrometry (LC-MS/MS) instrumentation.⁷ The drug classes tested consisted of nonsteroidal anti-inflammatory drugs, alcohol, alcohol metabolites, barbiturates, benzodiazepines, synthetic cannabinoids, cathinones, general anesthetics, muscle relaxants, neuroleptics, opiates, semisynthetic opioids, opioid antagonists/analgesics, stimulants, hypnotics, antitussives, antidepressants, cannabinoids, antipsychotics, anticonvulsants, antihistamines, and illicit drugs.

To demonstrate the prevalence of drugs detected in paired samples, participating medical examiners and coroners simultaneously collected oral fluid, blood, urine, vitreous fluid, and tissue from five postmortem decedents. Oral fluid was collected and analyzed per our laboratory procedures, whereas the remaining matrices were sent to outside reference laboratories for analyses (lab SF and labs A–D, respectively). These cases demonstrate the matrix, number of drugs quantified, and turnaround times (Fig. 1). In some instances, several matrices were collected but not tested, and not all presumptive positives were quantified, resulting in lengthy turnaround times compared with oral fluid. For example, in case No. 1, four of the eight presumptive positive results were not quantified, even with the analysis of an additional matrix. However, 11 drugs were quantified within seven hours using oral fluid. The importance of evaluating drug concentrations is to determine if drugs are within the range of being toxic or lethal, which is impossible to do if relying only on qualitative findings.

Oral fluid collected, processed, and analyzed from a postmortem decedent is a novel, alternative matrix in forensic toxicology for detecting and quantifying drugs, generating results comparable to the historical gold standards and/or sometimes even detecting more drugs than the gold standards. Furthermore, in instances where cases would be considered indeterminant due to insufficient and/or unavailable matrices, such as with decomposition (up to 174 days postmortem), drowning, charred bodies, embalming, homicide, suicide, motor vehicle accidents, factory and train accidents, or in stillborn babies, oral fluid has proved otherwise.

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