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Gas Chromatogram

Here’s what the graph from a Gas Chromatogram looks like


“What is a gas chromatogram?”

Seems like a simple question, but it gets to the heart of who’s out there purporting to be a DUI Defense Attorney. Whether the person knows the answer shows whether DUI defense is what they do – or just another in a long list of things they advertise for.

The answer is:

A chromatogram is a graphic representation of the test that’s done by the cops to determine the accused’s blood alcohol content at the time of the test.

If the person who wants to be your DUI Defense Lawyer can’t answer the question, or says it doesn’t matter, you need to thank that person for their time and leave.

I was recently in Court fighting to get the Chromatograms for my client and I was the only one in the room who knew what a Chromatogram was. I had to explain what Chromatograms are to the Judge AND the Prosecutor. Other Lawyers were taking notes about chromatograms – because they didn’t know.

Judges and Prosecutors ask all the time: “Why do you need to see that?” because most other lawyers aren’t asking to see these essential test results.

Blood tests can be fought – ALL DUIs can be fought – and knowing whatc hromatography machines are and exactly how they work is essential to that fight. Gas chromatography machines are NOT infallible. If you know where to look, you can find that the machine or the blood sample are probably contaminated.

Even if your DUI doesn’t involve a blood test, if it’s a refusal or a breath test, not knowing the answer to this question discloses that the person you asked doesn’t really know what he or she is doing. Chances are they’re just saying what you want to hear in order to get hired and they will just be going through the motions during your case. Chances are no matter how great what they say sounds,when they’re trying to get hired, you will end up pleading guilty to a DUI.

If your case does involve blood testing, the Lawyer who can’t answer your question will probably end up telling you, “It’s a blood test, there’s no way to fight that.” Without even looking at the chromatograms!

You’re going to end up spending thousands of dollars, even if you hire a cheap “Do Nothing” Attorney. It’s important to your future; you should know what to ask and know what you’re getting. Even if you settle for the guy who doesn’t know what a chromatogram is, you should know your Lawyer’s limitations.

Here’s How the Breath Test Works in Los Angeles County.

In Los Angeles, the CHP and LAPD use the Intoximeter EC/IR machine to breath test those they arrest for DUI. This is the test that you should not refuse (the implied consent test). The one given at the police station.

The EC stands for electrochemical and this is how this machine tests the amount of alcohol in the subject’s breath. There is a small wafer about the size of a quarter in a chamber inside the machine. The wafer is covered in platinum stretched thinly over an acidic electrolyte. A positive electrode is attached to the top of the disk and a negative electrode is attached to the bottom of the disk.

A small (1 milliliter, 0.001 liters, 0.1 cubic centimeters) sample of the subject’s breath is drawn into the chamber containing the platinum disk.* The breath is drawn at the end of a sustained breath to insure that deep lung air is tested. A portion of the 1 ml sample alights on the platinum.

When the alcohol vapor in the breath sample lands on the platinum/electrolyte, the O-H bond of the alcohol (C2H5OH) is oxidized. The positive H ion at the end of the molecule is removed and floats to the bottom of the disk. This creates an abundance of electrons (-) at the top of the disk and an absence of electrons on the bottom because of the migration of the H(+) ions to the bottom. the electrons then move from the positive electrode at the top of the disk to the negative electrode at the bottom of the disk.

This creates a charge in the fuel cell which is led off by the negative electrode and measured. The oxidation process creates a net of two electrons per molecule of alcohol. The greater the amount of alcohol present in the test chamber, the more electrons produced.

The IR in EC/IR stands for infrared. Infrared is used to control for mouth alcohol in the EC machines because the do not do so on their own (traditional machines contain a slope indicator to control for mouth alcohol). Infrared technology shines an infrared beam (across a chamber filled with mouth air). The alcohol in the mouth air absorbs the infrared at 3.45 microns and 9.5 microns.

* An average male adult’s lung volume is 4.8 liters or 4800 milliliters. The sample size is 1/4800 of its representative population. Blood Alcohol is measured statutorily as grams per 210 liters.


If you  have been given a Breath test and registered,  there are ways to fight a DUI conviction.. We know the science aand we will fight for you. Call Edward J. Blum at 213-479-5322 or fill out the easy form at right for your Free Consultation.

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