Stefan Rose, M.D., Updates the Forensic Reliability of Blood Alcohol Testing by GC-FID-MS Analysis
The accuracy and reliability of blood alcohol testing has always been an issue of much debate. Lending a voice to this ongoing discussion is one of the country's top forensic experts, Stefan Rose, M.D.
PALM CITY, Fla., June 13, 2019 (Newswire.com) - With over 40 years of training and experience in forensic toxicology, general psychiatry and clinical pathology, Stefan Rose, M.D., is more than a physician. An expert and specialist in the field, Dr. Rose is a skilled researcher, highly sought-after lecturer and teacher, a well-respected consultant for various court cases and unquestionably one of USA's foremost forensic experts.
It is no wonder then, that Dr. Rose's thoughts on the matter of blood alcohol testing, and the forensic reliability thereof, is of paramount interest to those in the forensic field of blood alcohol testing.
Several methods exist to determine alcohol in human blood samples, whether the sample is whole blood, serum or plasma. Those methods include enzyme assay (not approved for use in criminal cases by the Florida Department of Law enforcement) and gas chromatography (approved by the Florida Department of Law enforcement). But gas chromatography is not a full description of the analytical method, as the detector used in the gas chromatography instrument must be specified. The standard detector used across the U.S.A. for over 50 years has been the FID (flame ionization detector). However, the FID does not specifically identify alcohol in a blood sample, resulting in both qualitative and quantitative errors and, as a result, many defense challenges to its reliability have occurred since its first use.
Today, the typical instrument configuration for the analysis of whole blood alcohol testing is the static headspace - dual column - dual FID setup (SH-DC-DFID). Much better than its predecessor, the static headspace single column single FID setup, the dual column method still suffers from one very important forensic error: co-elution. Co-elution is the circumstance whereby another volatile organic compound (VOC) has the same or similar characteristics of alcohol and causes a false positive test result. This type of error is common with single column GC-FID methods and less common, but not eliminated, with dual column GC-FID methods. Dr. Rose has demonstrated in a laboratory at Florida International University that even a properly configured SH-DC-DFID instrument can experience the co-elution of other VOCs with alcohol, resulting in a serious forensic error. In Florida, most blood alcohol tests are done in the investigation of motor vehicle serious bodily injury and death cases, so this forensic testing should be without error.
However, there is an improved blood alcohol testing instrument commercially available, configured as a gas chromatograph with a single GC column but two different detectors - the already familiar FID detector and the mass spectrometer detector (MS). The MS detector has been and is the gold standard detector for identifying unknown drugs in the blood (often controlled substances like fentanyl, cocaine, marijuana and other prescription medications).
Dr. Rose testified over 20 years ago that the forensic community should implement the MS detector in the analysis of blood alcohol samples when he was the director of the University of Miami Forensic Toxicology Laboratory in Miami, Florida.
The advancement and utility of the improved GC-FID-MS instrument is that the MS detector helps to rule out a co-eluting, interfering VOC that may be in the blood sample and cause a false positive alcohol test result. Two laboratories in Florida have this instrument: the Palm Beach County Sheriff’s office in West Palm Beach, Florida, and the University of Miami Forensic Toxicology Laboratory, Miami, Florida.
However, no analytical instrument method is foolproof and even with this advanced and improved method of blood alcohol analysis, errors may still occur so it is essential that for any blood alcohol test performed and reported out in a formal investigation, the blood testing information should be reviewed by a qualified expert. Dr. Rose has been trained on GC-FID and GC-MS instruments and is fully qualified to review all documents in any such investigation.
In cases involving alcohol levels and intoxication, it is of utmost importance that an individual gets the correct legal and forensic counsel. Stefan Rose, M.D., continues to lead the charge in helping to shed light on the ever-evolving issue of blood alcohol testing and its reliability.
Even if the blood alcohol test is correct:
The only time a blood alcohol test result determines the alcohol concentration in a person at the time of driving is if a blood sample is collected from that person within minutes of a DUI stop or crash. The blood alcohol concentration is constantly changing with the passage of time in every person, so the longer the time interval from the stop or crash, the less is known about the blood alcohol level at the time of the stop or crash. The blood alcohol test results alone are not enough to prove what the person’s blood alcohol level was at the time of the stop or crash.
STEFAN ROSE M.D., FORENSIC PHYSICIAN & TOXICOLOGIST
Source: Stefan Rose, M.D.