6 February 2012
Assistant professor of criminal justice Chi-Chung (Jorn) Yu is studying a new biomarker for cyanide poisoning, which may extend its detection window in death investigations by weeks, if not months.
Unless cyanide is found at the time of death on the mouth or nose, elevated cyanide concentration can only be found for up to two days under current toxicological testing, according to Yu.
A recent study in Yu’s laboratory found that a biomarker, ACTA (2-aminothiazoline-4-carboxylic acid), was found significantly increased in liver samples following a sub-lethal dose of cyanide.
They also found that the substance could serve as a stable biomarker for a longer period of time.
“We think this is proving to be a reasonable marker for cyanide poisoning,” Yu said. “We want to be able to extend the detection window up to weeks or even months.”
Cyanide exposures commonly originate from smoke inhalation or direct exposure to either cyanide salt or hydrogen cyanide (HCN) and occur in military, firefighting, industrial and forensic settings. The study is an byproduct of research by SHSU associate professor of chemistry Ilona Petrikovics to find a antidote for those exposed to cyanide from a bioterrorism attack.
In the investigation of deaths, a bitter almond odor emanating from the victim and the presence of pink lividity during postmortem examination are two common indicators of acute cyanide poisoning. Alkali burns of the gastrointestinal tract often can be observed during autopsy in cases where cyanide salts have been ingested, Yu said.
Since cyanide salts are solid crystalline, their presence in a crime scene or in the areas near victim’s nose or mouth can be easily discovered, collected and preserved for further forensic testing. In cases where no suspicious substances are observed in the scene of the death, the presence of cyanide in the victim’s body can be confirmed chemically using a colorimetric test, followed by a laboratory analysis using a gas chromatography–mass spectrometry (GC-MS).
Forensic evidence, such as stomach contents and whole blood of the victims, are usually collected and analyzed in order to confirm the cause of death. The toxicological detection of cyanide involves extraction and measurement of HCN from biological extracts. Blood or urine also can be collected from the victim for laboratory analysis, according to Yu.
“Due to the relatively short half-life of cyanide—from minutes to hours depending on the matrix—toxicological detection of cyanide to confirm cyanide poisoning may only be feasible within the first few hours following exposure,” he said. “Moreover, the volatility and reactivity of cyanide leaves direct measurements highly susceptible to errors introduced during the sample collection and separation step.
“Cyanide levels in blood samples taken at autopsy the next day have been reported to decrease by approximately 79 percent. Postmortem formation of cyanide may also occur and complicate the interpretation of cyanide results,” he said. “Therefore, the presence of cyanide becomes less feasible when the detection window is passed or the victims’ body has been damaged by fire or advanced decomposition. The detection of stable biomarkers of cyanide is needed to extend the time in which cyanide exposure can be reliably assayed in a post mortem examination.”
The research was recently published in two journals, “Biomarkers” and “Analytical Methods.” Yu’s research team comprises Petrikovics, David Thompson, Gary Rockwood, Brian Logue, Sarah Martin land Prashanth Jayanna.
Yu’s laboratory continues to work on ATCA’s in vivo behavior and stability in order to explore the potential of using ATCA as a biomarker for cyanide poisoning. Future research may include looking for the presence of ACTA in the bones of victims with cyanide poisoning to extend detection methods even further.
In addition to his work on cyanide poisoning, Yu is researching other issues in the areas of trace evidence in forensic science, including, fire debris, gunshot residue and a new micro extraction device for blood and urine.
“We are looking for new methods and advanced materials with forensic applications,” he said.
Source: Sam Houston State University