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| image courtesy of web.nnsu.edu |
Testing Blood Evidence in New York:
Basics of GAS CHROMATOGRAPHY
for DWI and DWAI Drug Cases
As you can imagine, the process of testing a liquid and breaking down its molecular compounds is a very complicated one. However, this page should help break down the absolute basics of how your BLOOD gets tested after a DWI or DWAI drug charge in any of the New York forensics laboratory.
New Mexico State University has a terrific page set up covering the basics.
GAS CHROMATOGRAPHY: a common type of analysis used by chemists to separate and analyze compounds that can be vaporized without decomposition. (Wikipedia)
HOW DOES IT WORK?
1. Your Blood sample is broken down into multiple samples to be input into the machine
2. Your blood is heated in the main part of the machine so that it turns into vapor (gas)
3. It takes different chemical compounds different amounts of time to change from the stationary phase (when it's liquid) to the mobile phase (when it's gas)
4. The blood sample travels along a "column" that is very long (can be 15-60 meters) so that the various compounds inside your blood get separated
5. The length of the column gives plenty of time and space for the various compounds inside the sample to be separated from one another [the goal is to achieve separation]
6. Upon reaching the end of the column, the separated compounds exit and get read one by one and a computer creates a CHROMATOGRAM that is read by the chemist.
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| Example of a Chromatogram, image courtesy of clinchem.org |
PROBLEMS WITH BLOOD GAS CHROMATOGRAPHY
UNLIKE BREATH TESTING where only one person is tested at a time, blood gas chromatography usually involves many different defendants' samples are tested simultaneously. The chemist or forensic technician could be testing 100s of blood samples AT THE SAME TIME. This creates a large margin for error. It provides many opportunities for things to go wrong...It raises many questions for me as a DWAI drug or DWI defense attorney.
Was your sample labeled properly and separated from other defendants? Was the machine working properly? When was it last calibrated? Was the mobile phase gas working? Was it heated right? Did the chemist properly extract your blood from the vacuum container? Could somebody else's blood contaminate the column before your sample is read? Did the compounds actually separate at the end of the column? Did any compounds come out repeatedly?
As you can see, there are a million ways this process can go wrong. That is why it is so critical to be able to understand and read the chromatogram itself. The chromatogram can show us if there was contamination, if the samples were properly separated, and if problems exist. You just need to understand how to read it. You also need to understand what a proper chromatogram looks like versus one that has problems on it. It is such a specialized scientific process that it is important to have a DWI or DWAI drug defense attorney who understands the science and handles these sort of cases on a regular basis.
Do you have questions about a DWAI drug case or DWI case where your blood was taken?
Call us: 607-229-5184
E: mike.ithacadwi@gmail.com
By Attorney Mike Cyr
www.ithacadwi.com
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COPYRIGHT CYR & ASSOCIATES 2015
