Lawrence Taylor's Drunk Driving Defense (5th Ed) references the differential to
be as high as 30%. Bottom line is this: You must ask the lab tech, "Did you
centrifuge the blood?" "Did you test serum/plasma or whole blood?"
3.
Hematocrit
Hematocrit is the percentage of your whole blood that is made up of cellular
material. If someone has a Hematocrit of 47, we are saying that 47% of their
blood is made up of cellular material, and the remaining 53% is plasma (mostly
water). The normal range for a male is 47%-- slightly lower for a female.
What happens if D had a Hematocrit of 60; i.e., he had a higher percentage of
cellular material, and they tested plasma? You're going to get a higher BAC
because you have a lesser volume of liquid. Alcohol will always gravitate
toward the liquid. So, you have a higher BAC result with higher Hematocrit. The
higher EtOH concentration results from the alcohol being contained in a lower
volume of liquid (the plasma). Note also that trauma can result in a lower
Hematocrit. Hospital records will usually show Hematocrit.
4. IV
before blood draw (Cross Reference Lactated Ringers)
Wouldn't more liquid tend to dilute the EtOH and give D a lower BAC reading
because we are increasing the volume of liquid because of the IV? No! Alcohol
tends to follow water in the blood. When you consume alcohol, you don't just
have alcohol in your blood stream. You have alcohol in your body tissues as
well. If you increase the liquid (as a result of an IV), that liquid tends to
pull more alcohol out of the tissue and artificially increases D's BAC. So, an
IV put into a person before a blood draw will artificially raise the BAC.
5. Blood
Test Kits
Expiration Date. Blood test kits (formerly
Becton-Dickinson) now manufactured by NIK Public Safety Inc. THESE KITS HAVE
EXPIRATION DATES. This pertains to the period that the vacuum in the vacutainer
tube is warranted. Each tube contains a preservative and an anticoagulant
(Discussed infra). A precise vacuum exists in the vacutainer tube to assure a
precise amount of blood will be drawn and be mixed with these chemicals in
precise ratio. If there is too much chemical and not enough blood, this can
effect your test result because
preservative and anticoagulant are salting out agents. (Discussed infra).
Also, if vacutainer leaks, micro organisms from the room air can enter the
sample. Fermentation is a result of combining blood with micro organisms. EtOH
is a byproduct of fermentation. There is no way to distinguish between alcohol
consumed by a subject and alcohol created by fermentation.
John Tarentino's DUI Journal of Law and Science, suggests that we
inquire as to whether the lab did a bacteriological assay of the D's blood to
rule our the production of a "Post Collection Forensic Artifact." In other
words, we want to ask the lab mope, "Did the lab test the blood for
bacteriological contamination?"
Chemicals in Vacutainer tube. Each vacutainer kit is
intended to take 10 ml of blood. Each kit contains two chemicals: 100 mg of
sodium fluoride (a preservative to prevent fermentation and neo-production of
EtOH) and 20 mg of potassium oxalate (an anticoagulant designed to prevent
clotting of the blood).
The first question you must ask is, "Were these chemicals in the vacutainer
tubes?" These chemicals are critical to an accurate test result. On
cross-examination, you want to ask the cop and the phlebotomist if he or she
checked the vacutainer tubes to confirm that powder was in the tubes?
Where was the blood kit kept prior to the blood draw? In the trunk
of the police car? For how long and under what conditions?
Instructions in blood kit. NIK kits have two sets of
instructions. One for the person drawing the blood and one for the cop. One of
the instructions pertains to MIXING of the blood immediately after the blood
draw. After the blood is in the vacutainer, the person drawing the blood is to
invert the tube 5 times. Then, the cop is to invert each tube 20 times. Tubes
must not be shaken. Purpose of inversion ritual is to assure proper mixing of
blood and chemicals in tubes.
6. Chain
of Custody
Is there a "secure refrigerator" with a log book. A break in the chain of
custody usually goes to weight and not admissibility. Some cases (New York) held
contra in extremely outrageous situations.
7. Gas
Chromatography
Distinguish - There are two types of G/C in blood analysis--direct measurement
of the blood sample and measurement of the gas in the head space above the
liquid.
Gas Chromatography (G/C) is a method of (a) identifying a substance and (b)
determining the concentration of that substance. The process is both
qualitative {what is it?) and quantitative (how much is there?).
Generally, a G/C consists of a steel column filled with a granular substance
(e.g., sand). That granular substance is coated with a nonvolatile liquid
chemical. Nonvolatile means the chemical won't combine with what you are putting
through the column.
We inject the substance that we wish to test into the column. The column is
sitting inside of an oven. The oven is keeping the column at a constant
temperature. As soon as we introduce our blood sample, it is immediately
vaporized. This vapor starts going through the column. The vapor of our test
sample is carried through the column on a stream of inert gas, usually hydrogen
or helium. The stream of gas is set at a specific rate of flow that goes through
the column carrying our vapor of the sample we are testing.
The internal standard (the N-Propel alcohol) is injected and mixed with the D's
blood. Then, a sample of this mixture is introduced into the chromatograph.
Usually the amount introduced is between one and ten
microliters of solution, ideally three micro liters of solution. This is a very
small amount of chemical being tested. An eyedropper yields 50 microliters of
liquid. N-Propel alcohol is being introduced into the chromatograph and
vaporized. The column is 1/8th of an inch in diameter.
Salting out chemical. In addition to the N-Propel
alcohol, the lab adds a chemical to the mixture to help the alcohol get out of
the liquid and into the vapor. The higher the concentration of salting out
agent, the more alcohol in the vapor. Too much salting out agent will
erroneously put too much alcohol in the vapor than should be in relation to the
alcohol in the liquid. This brings us back to our chemicals in the vacutainer
tubes. Sodium fluoride and potassium oxalate are salting out agents.
7(A) Gas
Head Space Chromatography
In gas chromatography you are actually testing D's blood. In gas head space
chromatography, you are testing the gas or vapor above the liquid--not the
liquid itself. The head space is the space above the liquid. The alcohol
evaporates (at a rate of speed determined by temperature) from the liquid to the
gas in the head space above the liquid. The alcohol will evaporate until it
reaches the point of equilibrium. Equilibrium is determined by temperature. The
higher the temperature, the more alcohol in the gas above the liquid.
By way of analogy, this is why core body temperature variation and expired
breath variation can artificially inflate a breath test reading. Breath testing
is based on the relationship between alcohol in the blood and alcohol
percolating from the blood into the vapor in the lungs. The
assumption underlying breath testing is that whatever alcohol is present in one
ml of breath, 2100 times that amount will be present in one ml of
blood. Dr. Hlastala debunks this assumption.
This same theory underlies gas head space chromatography. With this process, the
lab makes up the same mixture of the blood plus the internal standard. They heat
the sample and draw off the vapor for analysis.Then the vapor is injected into
the chromatograph. How do we know that there is a relationship between the
alcohol in this vapor and the actual alcohol in the blood? Now, we get into all
of the considerations regarding Henry's Law. How is the temperature regulated?
What was the temperature? What is the relationship between the EtOH in the head
space and the EtOH in the blood? The primary disadvantage to head space
chromatography is the partition ratio and the effect of temperature and
pressure.
Themes for Case
"They didn't check to confirm the chemicals were there."
"They didn't do the things necessary to assure a proper mix between the blood
and the chemicals in the vacutainer tubes."
Were the chemicals in tubes in the proper concentration?
"They didn't look." "They didn't know." "They didn't care."
Potassium oxalate - The anticoagulant. 20 mg of
potassium oxalate is used to prevent blood from clotting. Remember, if blood
clots, the EtOH goes to the liquid and increases BAC reading. Potassium oxalate
combines with calcium ions in the blood to prevent formation of flambin. Flambin
is a clotting element. If blood clots, we are going to get a higher EtOH
concentration in the liquid above the clot. Any clotting is going to raise the
BAC. After the blood draw, but prior to analysis, you can do a test to determine
if the anticoagulant is present. That test is call "Ion Chromatography."
ASK THE LAB TECH: "Can you do it?" "Did you do it?"
We are establishing a theory that the lab just didn't care to perform the tests
necessary to assure a higher than accurate test result. What if the lab guy
says, "Well, if the blood clotted, I would have seen it upon visual inspection."
WRONG! Blood can form micro clots that can't be
seen upon visual inspection.
Sodium Fluoride - The Preservative. The 100 mg of
sodium fluoride is a preservative to prevent formation of EtOH by fermentation
of the blood. Fermentation of blood can have a dramatic impact upon EtOH
concentration. A blood sample with no alcohol can generate .25% BAC or higher as
it decays. This "neo-genesis" type of alcohol cannot be distinguished from the
alcohol they are testing for. Refrigeration will slow down the fermentation
process, but not prevent, fermentation and the production of alcohol.
Where do preservative and anticoagulant come from? NIK
purchases the chemicals commercially, in bulk. Then, NIK mixes them in bulk. A
measured amount of each chemical is dropped into the vacutainer tube as it goes
down the assembly line. NIK does not sample the vacutainer tubes once the
chemical is in it. The presence, and amount, of chemical is critical. If the
tubes aren't tested, how do you know them chemicals are there and there in the
proper concentration?
Questions for lab technician. "You've never tested a
vacutainer tube to determine if the proper concentration of chemicals were
present"? "You couldn't be bothered to confirm that just one of the tubes had
the proper amount of chemicals in it"?
A.W. Jones is on record that, in order to prevent fermentation, you need 100 mg
of sodium fluoride in the tube.
Interesting Demonstrative: Compare state's dark, gunky blood with bright red
blood from a fresh blood draw. (Perhaps client will volunteer for a de novo
blood draw)
Machine error. Like the IR 5000, Intoxilyzer or
any other breath test machine, the G/C has a margin of error under our administrative regs.
Most crime labs in Maricopa County claim to be accurate to within 3-5%. In fact,
their actual accuracy can be much less precise.
Summary
The key to attacking the chromatograph is the standards. The accuracy of the
process depends on what you tell the chromatograph the standards are. The lab
tells it what a .10 looks like; what a .20 looks like, etc. Everything is a
comparison. If the standards are off, the test is garbage. Where do the
standards come from? Who prepared the standards? If the standards are
commercially purchased, did the lab verify the standards? Did they test the
standards on that chromatograph? The integrity of the whole process is
determined by the accuracy of those standards. Did the low bidder get the
contract for those standards? Chromatography rides on the validity of the
standards that are used to calibrate the chromatograph.
