In Polymer Solutions Incorporated’s March 2011 newsletter, founder and CEOÂ James Rancourt describes what it’s like to serve as an expert in lawsuits.Â He talks about the many different facets that go into serving as an expert. For instance, by agreeing to testify in court, there is often the implicit assumption that Rancourt will be available around the clock for the case, no matter what may be going on in his personal or professional life.
Rancourt says his first case serving as an expert sticks in his mind. It involved involuntary manslaughter charges against a heating system repairman. The repairman stood accused of causing a home resident’s death because the coroner’s report indicated the presence of carbon monoxide in the deceased’s lungs. Carbon monoxide is a colorless, odorless, and tasteless gas that kills when inhaled for too long. The presence of the gas was taken as proof the man had died from carbon monoxide released by aÂ heater incorrectly installed by the repairman.
The coroner used gas chromatography (GC) with a thermal conductivity detector (TCD) to determine the presence of carbon monoxde. GC is a common form of chromatography in analytical chemistry that separates and analyzes compounds that can be vaporised without breaking down inside a column. GC is used, amongst other things, to test purity of substances, separate different components of a mixture, or identify a substance.
A TCD is often used with GC to detect compounds. It senses changes in the thermal conductivity of the gas coming out of the GC column and compares it to a reference gas. Most compounds have a thermal conductivity much less than that of the common reference gases, such as helium or hydrogen. When an analyte emerges from the column, the thermal conductivity goes down, and the detector produces a signal.
But Rancourt testified in court,
TCD is not able to identify a chemical’s identity. I further explained that the use of a single chromatography column and a peak having a retention time consistent with carbon monoxide does not verify that the peak is in fact carbon monoxide. The coroner should have used a second different chromatography column or should have used a spectrometric detector.
Further, the coroner had indicated an approximate concentration of carbon monoxide but did not account for the fact that carbon monoxide is present in the earth’s atmosphere. The formation of carbon monoxide within the lungs of the decedent, post mortem, was also not addressed by the coroner.
The heating system repairman was acquitted.
Source: Polymer Solutions Incorporated e-Newsletter, March 2011. Check out the archive of other PSI e-Newsletters on the company website.
Image by Michael Pereckas/Beige Alert, used under its Creative Commons license.
Rajendrani "Raj" Mukhopadhyay is a science writer and editor who contributes news stories and feature articles on scientific advances to a variety of magazines. Raj holds Ph.D. in biophysics from Johns Hopkins University.