The Basics of Blood Alcohol Testing by Gas Chromatography – Part II

September 19th, 2014 Allen Trapp Posted in Blood Test, Chemical Test No Comments »

The various solutes travel through the column at different rates. The fastest moving solute exits (elutes) the column first then is followed by the remaining solutes in corresponding order. After the compounds have been eluted from the end of the column, they must be detected, one at a time. As each solute elutes from the column, it enters the heated detector. An electronic signal is generated upon interaction of the solute with the detector. The size of the signal is recorded by a data system and is plotted against elapsed time to produce a chromatogram.

The plot created by this process is called a chromatogram. The size of the signal is proportional to the amount of a compound in the sample. In conjunction with the data recorder, an integrator is frequently used to provide measurements of the height of the compound’s signal and the time that it took for the compound to elute through the column and reach the detector.  While many types of detectors exist, the most common detector used for the blood alcohol analysis is the flame ionization detector. The flame ionization detector simply burns each organic compound as it elutes from the column. As the compound burns, it produces an electrical signal. The electrical signal is displayed as a “peak” with a known retention time. The period of time between injection and reaching the detector is referred to as the retention time.

The retention time of a compound alone is insufficient to identity of compound. The retention time of a known compound must be compared to the retention time of the unknown compound to determine if the known compound also exists in the testing sample. By comparing the retention time of the compound to a known standard, the compound can be identified. Identifying the compound is the qualitative portion of the analysis.

The concentration of alcohol in a sample is measured by comparing the size of the peak produced by the testing sample to the size of the peak produced by different known concentrations of alcohol.   Measurement of the amount of the compound in the sample is the quantitative portion of the analysis.  Each compound has a different retention time with a particular mobile phase, stationary phase, and temperature. If testing conditions change, identifying the compound is not possible. Therefore, the instrument must be periodically tested with a known specimen to ensure the testing conditions have not changed and the calibration of instrument remains intact.

Written by Allen Trapp who is board certified by the National College for DUI Defense and the author of Georgia DUI Survival Guide Visit Website
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The Basics of Blood Alcohol Testing by Gas Chromatography – Part I

September 19th, 2014 Allen Trapp Posted in Blood Test, Chemical Test No Comments »

The first stage of sample testing is the injection of the sample into the injector port. The sample is introduced into the injector port with a syringe or an exterior sampling device known as a pipette. The injector port is a hollow, glass-lined cylinder that is heated to 150-250°C which causes the sample to vaporize.

Most blood alcohol analyses are performed via headspace gas analysis as opposed to direct injection. A small amount (approximately 0.10 milliliters) of blood is diluted with water to about 1.0 milliliter in volume. The sample is placed in a sample vial and the cap is crimped and placed in an auto sampler with an incubating chamber set at a constant temperature. When the sample has reached equilibrium (when the rate of ethanol evaporation equals the rate of condensation in the sample vial), a sample of the gas above the liquid is withdrawn and injected into the gas chromatograph.

At this stage of the analysis Henry’s Law is in effect. Henry’s Law is a chemical principle that describes therelationship of volatile compounds in dilute aqueous solution at equilibrium.  Next, the vapors of the sample are carried into the column by a carrier gas.  The transportation of the vapors by the carrier gas, usually hydrogen, helium, or nitrogen is frequently referred to as the mobile phase. The carrier gas flows into the injector port, through the column, which is maintained by a temperature controlled oven, and then into the detector. The solutes travel through the column at a rate primarily determined by their physical properties, and the temperature and composition of the column. The column is packed or coated. This is commonly referred to as the stationary phase.

Written by Allen Trapp who is board certified by the National College for DUI Defense and the author of Georgia DUI Survival Guide Visit Website
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The Very Basics of Blood Testing

July 21st, 2014 Allen Trapp Posted in Blood Test No Comments »

     A proper blood sample collection must accomplish three things. First, the collection method must protect the integrity of the sample from anything that could change the alcohol concentration of the blood. Second, the method of collection must provide a sufficient quantity of blood for the testing process. Third, the collection process must be medically safe for the subject and for storage. The blood testing kit must not be expired or have contamination.

     In most states, the testing of a suspected impaired driver begins with the blood draw. The suspect is transported to the jail where an on duty nurse secures a sample of the suspect’s blood. The blood can often times be secured by a registered or licensed nurse at a local hospital. Once the blood is secured it should be placed in an area where it can remain stable. The sample should also remain tamper free by methods such as tamper resistant seals or under lock and key by a single evidence custodian. The sample is then transported to the appropriate agency for testing and analysis. In most states, the testing of a suspect’s blood is governed by rules of the state crime laboratory, the Department of Health or the Department of Public Safety. Once the sample reaches the agency, the sample is received by a person who will accept responsibility for the assignment of a case number or other identifying tracking feature. The sample is then placed in storage where it will remain for a period of time prior to testing. Once the testing procedure begins the sample will be placed in an identifying slot where analysis can take place. The testing device and the method used must assure accuracy and reliability by having constant controls, machine calibration and peer review. The results are then reported to the requesting agency. As in standardized field sobriety administration, the failure at any stage to comply with common sense and validated scientific procedure can compromise the validity of the end result.


 

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More on Hospital Blood Tests for Alcohol

April 5th, 2014 Allen Trapp Posted in Blood Test No Comments »

In an enzymatic test, the type customarily performed when a patient is brought into the emergency room at a hospital, the analysis for alcohol concentration is typically performed on serum or plasma samples, so it is important that you do not assume that the test was performed on whole blood. To measure the alcohol concentration through an enzymatic assay test, the serum or plasma is combined with an enzyme, alcohol dehydrogenase, to form acetaldehyde. Coincidentally, acetaldehyde is the first and most important metabolite of ethyl alcohol.

During this process, nicotinamide adenine dinucleotide (NAD) is converted to NADH. The concentration of NADH is measured to determine the alcohol concentration. Plasma and serum are quite different and have different water content levels. Because alcohol distributes to the different components of the blood according to the water content, the relative water content level of plasma and serum is an important consideration.

Plasma and serum have nearly the same ratio of water to blood and should produce similar alcohol concentrations. The ratio of serum to whole blood varies widely, with at least one study showing the ifference can be as great as 49%. However, a statistical average of about 1.18 seems to be indicated.

The serum or plasma alcohol test is indirect. The amount of NADH, which is an enzyme, is measured spectroscopically at the 340 nanometer wavelength. The amount of NADH present is supposed to be proportionate to the amount of alcohol converted by ADH to acetaldehyde. However, when lactic acid is produced due to stress on muscles resulting from an injury or when ringers lactate is administered by paramedics, LAD will also react with ADH and be read as ethyl alcohol by the enzymatic tests.

In most cases these hospital reports will have “Not for Legal Purposes” written or stamped across the front. However, do not be surprised if zealous prosecutors attempt to use them, and at least in Georgia, they will usually be admissible. Therefore, defense counsel must be prepared to deal with them.


Written by Allen Trapp who is board certified by the National College for DUI Defense and the author of Georgia DUI Survival Guide Visit Website
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Warrantless Blood Draws: Supreme Court Has Doubts.

April 18th, 2013 Allen Trapp Posted in Blood Test, Case Law Update No Comments »

Just this week the U.S. Supreme Court decided the case of Missouri v. McNeely.  The Court held that the mere passage of time (resulting in the metabolism of alcohol) did not justify a warrantless blood draw.  The Court did not outlaw all non-consensual warrantless blood testing in DUI cases, but they should now be rare across the country.  The Court disagreed with the State of Missouri, which argued that the passage of time created an “exigency” which justified the failure to obtain a warrant.  Georgia law did not purport to allow forced blood testing without a warrant, but some aspects of our implied consent law may now be called into question. 
Written by Allen Trapp who is board certified by the National College for DUI Defense and the author of Georgia DUI Survival Guide Visit Website

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At Least One Court Insists on Valid Blood Tests

April 18th, 2013 Allen Trapp Posted in Blood Test, Case Law Update No Comments »

Hunter v. State, 55 A.3d 360. Del. Supr., (2012).

The Supreme Court of Delaware found that the admission of a test result that was not in compliance with the manufacturer’s requirements.? Furthermore, this error jeopardized the fairness of the trial.? Specifically in this case, using the expired vacutainer tubes in the blood test kit was in direct contravention of the manufacturer’s specification sheet for the vacutainer tubes. The same was true of shaking the tubes vigorously, which was also in direct violation of the manufacturer’s instructions for use of the kit.
Written by Allen Trapp who is board certified by the National College for DUI Defense and the author of Georgia DUI Survival Guide Visit Website

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Acetone in Blood Alcohol Tests

February 4th, 2011 Allen Trapp Posted in Blood Test, Chemical Test No Comments »

     Something we are seeing more frequently in gas chromatograms, the charts that show how much of certain substances were found in a person’s blood by the state crime lab, is the presence of acetone.  Sometimes, the crime lab actually reports the amount of acetone in their two-page summary, which is all that most prosecutors or defense attorneys ever see, but more often than not they don’t.  We have also seen a number of tests with isopropyl alcohol present in the blood.

When acetone and isopropyl alcohol are present, it means that the person is probably an uncontrolled diabetic.  Acetone alone is also indicative of this problem.  So what impact does diabetes have on a blood test?  It means that the person has an elvated glucose (sugar) level in the blood, and that sugar with just a little help from an organism known as candida albicans will be fermented into alcohol.  In other words, the sugar in the blood of an uncontrolled (and sometimes undiagnosed) diabetic will be converted to alcohol, which will result in an erroneously high result.  This is particularly true if the blood is not refrigerated, which it never is while it spends three to four days in transit to the crime lab.  The blood alcohol level reported will not be adjusted to reflect the increase in the amount of ethyl alcohol in the blood caused by the endogenous production of alcohol.

The bottom line is that innocent people will be convicted.  An attorney who knows what to look for and a highly qualified forensic toxicologist who knows how to find it are your best protection.
Written by Allen Trapp who is board certified by the National College for DUI Defense and the author of Georgia DUI Survival Guide Visit Website

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Blood Alcohol Tests: The Hematocrit Conundrum

October 8th, 2009 Allen Trapp Posted in Blood Test, Chemical Test 1 Comment »

     Whole blood is comprised of red and white blood cells, platelets and other clotting and cellular material, dissolved salts, amino acids, fats, and water.  Those solid materials are frequently referred to as “hematocrit.”  The hematocrit level is, therefore, the percentage of the total volume of blood taken up by the solid particles.  Determining a person’s hematocrit level at the time the blood is drawn is the only way to know what the correct conversion ratio is for the person who was tested at the time of the blood alcohol test.

     The average hematocrit for men is 47% with a “normal” range between 42% and 52%.  The average for women is 42% with a range from 37% to 47%.  Studies have shown, however, that over time an individual’s hematocrit can vary by up to 15%. 

     In general, the higher the hematocrit level, the higher the reported blood alcohol concentration in a serum or plasma test, which is the kind most frequently encountered in a hospital setting.  The higher someone’s hematocrit level, the less liquid we can expect to find in their blood.  Since the alcohol will migrate or remain with the liquid portion of the blood, a person with a higher hematocrit will have a higher blood alcohol test result when that blood alcohol test is a plasma or serum test performed in a hospital. 

Written by Allen Trapp who is board certified by the National College for DUI Defense and the author of Georgia DUI Survival Guide Visit Website
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Linearity in Blood Alcohol Testing

June 28th, 2009 Allen Trapp Posted in Blood Test, Chemical Test No Comments »

     Linearity is determined by testing known samples of various concentrations, which should ensure that the tests of other samples of unknown concentrations should yield accurate results.  Linearity enables an analyst to have confidence in the results of a particular test based on the results of other tests.  For example, if a known alcohol concentration of .10 is determined to be .10 and a known concentration of .20 is determined to be .20, this greatly increases the likelihood that a blood alcohol reading of .15 is accurate.

     In most cases the linearity of a gas chromatograph is checked at the beginning of each set of tests (a “run”) by injecting calibrators of varying amounts in the GC.  By plotting the amount of each calibrator versus their relative instrument responses, a linear relationship may be established.  The concept of linearity is associated with the “range” of the instrument, which is the interval between the highest and lowest concentrations that have been determined to be not only linear but accurate and precise.  Accuracy means that the testing device has correctly determined the true result, while precision is the ability of the instrument to replicate the test result.  Therefore, even if a blood alcohol test is “precise,” that merely means that the testing instrument has printed the same result more than once.   As defense attorneys we concentrate on accuracy – whether it can be proven that a blood alcohol test result has determined the correct result.

     It is generally agreed that good laboratory practice requires the use of six calibrators spanning the range of 50 to 150% of the expected range of results the analyst expects to encounter in typical cases.   In other words, the concentration of the calibrators should be such that they bracket the anticipated concentration of the specimen.   The Laboratory Guidelines of the Society of Forensic Toxicologists recommends “at least three calibrators.”  If any result exceeds the range, the substance being tested should be diluted and retested.  If the concentration of the specimen is less than that of the lowest calibrator, in most cases an additional calibrator below the expected range of the analyte in the sample should be set up. 

Written by Allen Trapp who is board certified by the National College for DUI Defense and the author of Georgia DUI Survival Guide Visit Website
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Blood Tests: The Differences Between Whole Blood, Serum, and Plasma

May 1st, 2009 Allen Trapp Posted in Blood Test, Chemical Test No Comments »

     If there is no anti-clotting agent in a tube used to collect blood, the blood will clot (due to the presence of fibrinogen in the blood). Upon centrifugation of the tube, the clear yellow liquid at the top is called serum and contains little or no fibrinogen because the fibrinogen has been used up in the clotting of the blood cells. A sample of the serum can then be removed for analysis of its serum alcohol concentration.

     If there is an anti-clotting agent in the tube, the blood should not clot if properly mixed (tube inverted a few times). The tube can then be either shaken and a sample of the whole blood can be then be removed for analysis of its blood alcohol concentration, or the tube can be centrifuged. Upon centrifugation of the tube, the clear yellow liquid at the top is call plasma and contains about 0.34 grams of fibrinogen per 100 mL of plasma. A sample of the plasma can then be removed for analysis of its plasma alcohol concentration.

     Because serum and plasma only differ by the absence or the presence of a trace amount of the fibrinogen protein, the serum alcohol concentration and the plasma alcohol concentration should be essentially identical. However, due to their higher water content than whole blood, the alcohol concentration in either serum or plasma should be about 18% greater on average than the actual whole blood alcohol concentration.No forensic testing laboratory would try to measure the alcohol concentration in a blood clot which, because of its relatively low water content, would be relatively low in alcohol concentration compared to the whole blood alcohol concentration.

Written by Allen Trapp who is board certified by the National College for DUI Defense and the author of Georgia DUI Survival Guide Visit Website
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Blood Alcohol Tests: Collecting the Blood

March 23rd, 2009 Allen Trapp Posted in Blood Test, Chemical Test 1 Comment »

     The first step in the blood collection process is decontamination of the area where the blood will be drawn.  In clinical use a prepackaged 70% isopropyl alcohol pad is the preferred antiseptic.  However, Betadine (povidone-iodine) is the swab of choice for forensic blood draws.  If Betadine is used, it must be allowed to dry prior to the puncture.  Studies have shown that sloppy swabbing of an injection site will increase a blood alcohol concentration.

     Most forensic laboratories purchase 10 milliliter gray top tubes containing 100 mg. sodium floride, a preservative, and 20 mg. potassium oxalate, an anti-coagulant.  Therefore, when 10 ml. of blood is drawn, the concentration of preservative is one percent.  A tube with an anti-coagulant should be inverted at least eight times (eight to ten is usually recommended).  If this is not done, the anti-coagulant will not properly mix, resulting in a low concentration, which in turn can lead to microclotting and an inaccurate result.  This is not just the wishful thinking of a defense attorney but is included in the instructions issued by the manufacturer of the blood alcohol collection tubes used in Georgia. 

Written by Allen Trapp who is board certified by the National College for DUI Defense and the author of Georgia DUI Survival Guide Visit Website

    

   

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Combined Influence of Alcohol and Drugs

March 19th, 2009 Allen Trapp Posted in Blood Test, Chemical Test, Driving under the Influence of Drugs No Comments »

     We are seeing more arrests for DUI where the breath alcohol concentration is not consistent with the manifestations of impairment described in the arrest report or captured on video.  In some, but not all of these cases, the culprit is detected by a blood test, and that culprit is some drug other than alcohol that the client has consumed.  As more and more people take selective serotonin reuptake inhibitors (SSRI’s) such as Paxil and Prozac, we will see more and more of these cases.

     Alcohol and many drugs do not simply have an additive effect; they have a synergistic effect.  That is to say that the effects of the two substances are not merely added together but are essentially multiplied.  When even an adult dose of acetaminophen may produce impairment equivalent to a BAC of .05, it is not difficult to understand how prescription medications combined with alcohol can cause serious impairment. 

     One of the other commonly abused drugs is oxycodone.  It is the narcotic found in Percoset (with acetaminophen) and Percodan (with aspirin).  It is a synthetic opioid and like its natural cousins can cause addiction and then withdrawal symptoms. 

     When we represent an individual with these drugs in his or her system at the time of arrest, it is almost always necessary to retain a pharmacologist or toxicologist.  Otherwise, an employee of the state crime lab will be the only “expert” in the courtroom, and that employee’s testimony, if unrefuted, will seal the defendant’s fate. 

Written by Allen Trapp who is board certified by the National College for DUI Defense and the author of Georgia DUI Survival Guide Visit Website
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Blood Tests: Potential Problems

October 11th, 2006 Allen Trapp Posted in Blood Test, Chemical Test No Comments »

When the police arrest an individual for DUI and arrange for blood to be drawn by a nurse, phlebotomist or other qualified individual, it should in all cases in Georgia be taken from the suspect via a vacutainer.  Two vacutainers (vials with a seal or septum at the top) are included in each blood alcohol testing kit provided to police agencies in Georgia.  Each of these vials should contain two substances -sodium flouride, the  preservative, and potassium oxalate, an anticoagulent.  Each of these tubes will be  vacuum sealed, which explains why they are called vacutainers .

The vacutainers also have an expiration date, after which the vacuum seal is no longer warrantied.  The expiration date will be printed on the outside of the blood testing kit, which is basically a small cardboard box.  The truth is that only a very small handful of  phlebotomists or police officers ever pay any attention to the expiration date, because they are rarely challenged on the issue.  In addition, state crime lab personnel don’t confirm the the expiration date.

The manufacturer’s quality control procedures only require that one out of every four thousand vials be checked.  The bottome line is that there are at least three possible defects in the state’s blood test:

1. A failed septum (or seal) on one or both of the vials, which cannot be detected after the blood in a tube has been tested, because that vial has been opened.

2. Improper amount of sodium flouride in one or both of the tubes.  Since the vacutainers are rarely if ever refrigerated before being dropped off at the the Division of Forensic Sciences, the proper amount of preservative is critical. Either too much or too little can lead to a false high test result. 

3. Improper amount of potassium oxalate in either of the tubes. 

In the case of a defective seal organisms from the environment, such as candida albicans, can get in.  Unless there is enough sodium flouride in the vial, the organisms that may be in your client’s blood will grow. The most common of these is candida albicans, a yeastlike organism that has proven to be highly resistant to sodium floride. When candida albicans is in close proximity to glucose and a source of heat, it will create ethyl alcohol via fermentation.

Too much sodium flouride may cause “salting out”, which will also lead to a false high test result with headspace gas chromatography. This can occur even if there is no problem with the vacutainer, but the phlebotomist draws too little blood.

If there is not enough potassium oxalate, the blood can coagulate or “micro-coagulate” which is almost completly undectable. Because this changes the ratio of liquid to solid in the substance that is tested, and ethanol is water soluble, it can lead to a false high test result.

It can be virtually guaranteed that in any case involving a blood test the lab did not test for the presence of Candida Albicans, the lab did not check the vial seal, and the lab did not check the amount of sodium flouride or potassium oxalate in the tube.

If any of these occurred, you will in all likelihood have a false high blood alcohol concentration reported by the lab.

Written by Allen Trapp who is board certified by the National College for DUI Defense and the author of Georgia DUI Survival Guide Visit Website
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Blood and Urine tests for Methamphetamine

August 11th, 2006 Allen Trapp Posted in Blood Test, Chemical Test, Urine Test No Comments »

     If a person has taken methamphetamine, that individual should also have its metabolite amphetamine in his or her system. In other words, levels of both methamphetamine and amphetamine should be detected in both the blood and urine. Some GC/MS assays can falsely yield positive methamphetamine levels when high concentrations of ephedrine or pseudoephedrine are present in the specimen. Depending on the temperature of the injection port, the ephedrine or pseudoephedrine can be converted (or cooked) to methamphetamine. Therefore, sound scientific practice requires a negative report for methamphetamine if only methamphetamine is found in blood or urine. The absence of amphetamine means that the person had not consumed methamphetamine, which would in the ordinary course of metabolism would produce amphetamine. Therefore, in a case where only methamphetamine is found in the blood or urine the person probably had a cold and taken cold medicine containing ephedrine or pseudoephedrine.

Written by Allen Trapp who is board certified by the National College for DUI Defense and the author of Georgia DUI Survival Guide Visit Website
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Blood Tests: Why a Hospital Test is Suspect.

August 4th, 2006 Allen Trapp Posted in Blood Test, Chemical Test No Comments »

Hospital laboratory testing of serum alcohol involves use of the enzymatic method. The enzyme kits do not measure alcohol directly. They oxidize alcohol to acetaldehyde by the reduction of NAD+ to NADH. The amount of NADH produced
is therefore a function of the amount of alcohol present in the sample, and the amount of NADH produced is measured via a color reaction. However, if the blood also contains high levels of lactate (lactic acid) from either the administration of Ringer’s Lactate or the release of lactate from damaged tissues and also high levels of LDH (lactate dehydrogenase) enzyme from damaged tissues, then it is possible that the NAD+ from the enzyme kits will also oxidize lactate to pyruvate, thereby also producing NADH which would appear as “alcohol” in the test results. Therefore, it may be possible to have falsely high alcohol test results from serum alcohol tests using these hospital enzyme kits if both lactate and LDH are in high concentrations in the blood.

Most cases with only a hospital blood test are homicide by vehicle or serious injury by vehicle cases, and either of these charges carries up to fifteen years in prison.  Therefore, someone in this situation needs to understand that an expert such as a professor of toxicology must be on your team.  Otherwise, the State will introduce unrefuted evidence that your blood alcohol concentration was at a certain level, and you will be on your way to prison.  Don’t cut corners when your life and liberty are endangered; make the investment. 

Written by Allen Trapp who is board certified by the National College for DUI Defense and the author of Georgia DUI Survival Guide Visit Website
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