Blood Analysis Lab for DWI Cases

The lab has several chromatographs and the one on the center left has a mass spectrometer attached. Mass Spectrometers are used to confirm gas chromatogram results in more serious case – more later.

Some chromatographs have auto loaders (to the left) which are programed to automatically inject multiple samples into the machine.

Before injection the blood samples have to be prepared in the “wet lab.”

Preparing the samples in the wet lab is the most important part of the process. If not done correctly, the preparation can destroy the ability of the machine to accurately evaluate the sample.

These machines are named for the desired characteristics of the process: “precision.”

Harold McNair: the class was taught by the world leaders in chromatorgraph. Dr. McNair wrote the text. He was hired by NASA to produce the smallest chromatograph which will forever remain on the planet Mars.

Its called gas chromatography because the gas in the sample container above the small amount of sample in the container is what is actually injected into the machine.


Most often the sample is drawn from blood tubes by automatic pipettes.

The process is tedious, and it is not easily subject to automation.

The sample bottles must be sealed for use.

The samples are placed in the autosampler.

The order of sample placement in the autosampler is critically important: who’s blood is being tested.

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