Court cases most commonly perform blood tests using a headspace gas chromatography
-based system as criminal evidence. Blood alcohol screening
tests are often only as reliable as the equipment and technicians involved, and there are lots of sources of error in blood tests.
Maintaining Procedural Controls Feels More Difficult Than it Should
Maintaining a good quality control program with optimized procedures is the basis for ensuring process controls are in place and routinely optimized. While no vendor can take ownership for maintaining the quality of your processes and procedures, they can offer solutions that make things easier.
Some common instrument-related procedural control
areas attorneys look to go wrong with this type of test:
- Non-sterile techniques or equipment during sample preparation
- Poorly calibrated and/or maintained test equipment
- Carryover from a previous test result
- Failure to repeat the test process or double-check each step
- Electrical and laboratory temperature interferences
- Software bugs that may impact the blood test equipment analysis results
- Defects in sample loops that carry the sample through the blood test equipment
- Carrier gas contaminants
- Defects in the heaters, worn or defective gaskets, seals and O-rings in the blood test equipment
See The Truth About Blood Tests
for a full list.
Carryover is Becoming a Nuisance
While baseline perturbations and carryover may not interfere with chromatographic peaks of interest, defense attorneys will focus attention on them. Baseline disturbances may be caused by a variety of issues, including contaminants in reference materials, septa bleed, dirty injection ports and sample loops, and temperature interference caused by ambient fluctuations These raise doubt.
Newer headspace autosamplers
offer “no sample loop” technology, which reduces the need for cleaning or replacing parts and eliminates sources of interference. Improved electronics are optimized to further reduce influence from ambient temperature fluctuations.
Carryover may become more problematic as your system ages or as you lower your testing limit requirements. Deploying automated sampling systems that include the fail-safe function for automatically cleaning your injection pathway can reduce routine maintenance.
Repairs and Maintenance are Becoming More Frequent
While your ability to repair your system may still be feasible, what is that downtime causing you? It is likely you have a series of performance checks you complete to ensure every repair or maintenance activity does not compromise the instrument performance and the results you report for use in criminal cases. This can quickly add unplanned costs to your organization in the form of employee time, increased maintenance and casework “send outs” to deliver test results.
Ever-Changing Regulatory Outlook
In Europe, the majority of countries have moved or are moving to 0.05 g/alcohol per 100 mL/blood. In the U.S., all 50 states impose 0.08%. But in 2013, we saw the National Transportation Safety Board (NTSB) propose getting tougher on drunken driving
and ask for states to drop the current blood-alcohol level of .08 to .05/100 mL, about the level caused by a dry martini or two beers in a 160-pound person.
While the NTSB has no authority to impose its recommendations, it provides an influential voice in the setting of safety standards. The Board’s proposal got an immediate positive response from an organization of state highway safety officials.
Can your current BAC system provide the sensitivity, linearity and throughput required if these changes progress in your jurisdiction?
Continuous Operation and Increased Throughput Requirements
According to some forensic code of regulation standards
, your method must be capable of analyzing a reference sample of known alcohol concentration within accuracy and precision limits of plus or minus 5% of the value. These limits should be applied to alcohol concentrations which are 0.10 grams per 100 milliliters or higher.
We’ve seen forensic institutions repeatedly run process improvement projects with the goal of providing faster toxicology
test results to prosecuting attorney and defendants while reducing the ability to maintain and control the chain of custody. In a 2014 project report, it was confirmed that the Wisconsin State Laboratory of Hygiene
tested almost 20,000 OWI (Operating While Intoxicated) samples in 2011.
If states in the U.S. dropped the current blood-alcohol levels, might this mean case sample volumes would increase to 2-3 times the level they’re at today?
Title 21 Code of Federal Regulations Part 11
You Want Your Software to Help You Monitor and View Changes
provided the pharmaceutical industry and suppliers with a guidance system to deploy computer systems and good standard operating procedures to ensure data integrity was maintained. We’ve seen ISO 17025
incorporating similar requirements. Before deploying new software (even incremental revisions), always ensure what you deploy can help you define and control system access, support your record retention policy, provide viewable audit trails to monitor fraudulent practices, and that it does not impact your validated method without your knowledge. Additional Resources
Visit our online Volatiles Screening and Quantitation
resource within our Toxicology community
to learn more about blood alcohol content analysis by gas chromatography
. Is your lab planning to migrate your BAC analysis to mass spectrometry-based technology? If so, I’d like to hear about your experience.