A forensic toxicologist at ETSU’s James H. Quillen College of Medicine has identified a procedure that scientists can use to estimate the length of time a person has been deceased.
The procedure is called capillary ion electrophoresis (CIE0 and is discussed in the latest edition of the Encyclopedia of Analytical Chemistry. ETSU professor Dr. Kenneth Ferslew says the method is effective in determining vitreous potassium concentrations to calculate postmortem interval, which is the time between when death occurred and an autopsy is performed.
Capillary ion electrophoresis was first developed in the early 1980s and has recently been introduced as a separation technique scientists can use for the analysis of ions. An ion is an atom or group of atoms that carries a positive or negative charge as a result of having lost or gained one or more electrons.
CIE can separate multiple positive or negative ions from extremely small samples in a single analysis.
In his research, Ferslew and co-author Andrea Hagardorn used CIE to assess the level of potassium in vitreous fluid, which is the liquid within the eye.
According to Ferslew, potassium ion concentration increases after a person dies. By measuring the amount of potassium, forensic scientists are able to predict how long it has been since a person’s death occurred.
Though experts have measured potassium levels before to establish time of death, Ferslew’s article is the first to address the use of CIE in gaining this information.
“While there are many approaches used for determining postmortem interval, such as body temperature, discoloration or slippage of the skins, there are situations when this data may not always be reliable,” said Ferslew, a professor in the ETSU department of pharmacology.
“For example, when a corpse is found submerged in cold lake water, the body temperature will be affected.
This can be even further complicated depending on the area of the United States involved because, as an example, the temperatures of our lakes in this region are much colder than in the Gulf Coast states.
“And, in situations where a body is found burned, you obviously cannot use body temperature or study the skin to determine how long the victim has been dead.”
Another benefit of CIE is that it takes only a few minutes to complete.
In addition to determining postmortem interval, Ferslew found that CIE is effective in establishing the levels of lithium.
“While lithium has been proven to be highly effective in treating manic disorders and other psychological problems, it can be toxic if serum concentrations get too high,” he said.
“It is often difficult to determine if a person has died from an overdose of lithium because the level of optimal use and the level where toxicity occurs are very close. In our research, we found that the CIE procedure helps give an accurate assessment,” he said
Ferslew is director of ETSU’s section of toxicology and is a member of the Upper East Tennessee Forensic Center, which serves several local counties.
He plans to continue his research on CIE and noted that a publication is scheduled for later this year demonstrating the application of the procedure in analyzing substances used to interfere with urine drug tests.

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