BCA Alcohol Lab Doesn't Use Proper Controls

Posted On February 06, 2023 Charles Ramsay

Last week, I told you about how the BCA doesn't calibrate the pipette used to analyze alcohol in blood and urine. This is a huge problem for the lab. The only way to know if the pipette you are using is working correctly is to calibrate it accurately against known standards. 

After listening to nonsensical testimony from the BCA, it isn’t likely that they will be calibrating their pipette any time soon. But all it takes is one judge to see their error and demand that they follow the science. 

It's hard to follow up a mistake like that with something bigger, but I've been digging deep into discovery, and I've found something just as bad, if not worse.

A massive oversight in the BCA blood and urine alcohol lab

Here’s the problem: The BCA doesn't run any matrix-matched controls with their alcohol analysis. All of their alcohol controls are water-based.

What does this mean? 

It means that the BCA hasn’t been using controls that match up with the blood or urine they’re actually analyzing.

This is a HUGE problem. 

It is well known that the matrix effect can have a tremendous effect on your results. The alcohol partition ratio in blood vs. water vs. urine is very different

If the state doesn’t account for the difference, they could be overestimating the alcohol concentration of samples by as much as 20%! Someone with a 0.070 g/100 ml of alcohol in their blood could falsely register as high as 0.084 g/100 ml by their machine.

What the science says

The only way to know the effect size is to run matrix-matched controls with each analysis. After you test a known control, you compare the answer to what it should have been.

Using matrix-matched controls is so important that the ASB Standard Practices for Method Validation in Forensic Toxicology demands you do it. 

Section 8.3 of the ASB standards states:

“The use of matrix-matched calibrator samples is encouraged…Regardless of the matrix used to prepare calibrator samples, a laboratory shall demonstrate acceptable bias and precision with control samples prepared in all matrices intended to be analyzed by the method (see Section 7.1) For example, blood alcohol methods may demonstrate acceptable bias and precision in whole blood controls…”


If that was too much to take in all at once, here’s the short version: the BCA isn’t following standard procedures required by forensic toxicology labs. This means that they could be overestimating their alcohol results by as much as 20%.

Left to their own devices, the BCA won’t change. At Ramsay Law Firm, we dig into the science to keep the State honest. Contact us if you’ve been a victim of the State’s shoddy science.

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