Volatiles screening and quantitation – Blood alcohol screening

Blood alcohol screening

What is the level of alcohol in biological fluid? A fair question, both from forensic and law enforcement stand point.

Overview: Blood alcohol content (BAC) analysis is one of the most common preliminary tests in forensic science. However, for purposes of law enforcement, blood alcohol content is used to define the level of intoxication and a rough measure of impairment. It is generally performed via headspace gas chromatography (GC) with a flame ionization detector (FID).

Method: The content of alcohol in blood is most commonly expressed as grams per deciliter (g/dL). Find out how to determine blood alcohol levels using the TRACE 1310 GC, the new TriPlus 300 Headspace autosampler, and Chromeleon CDS software solutions.

Results: Calibration curves are prepared for methanol, ethanol, isopropanol, and acetone. Method repeatability was tested for most common volatiles on 20 consecutive injections of the same sample.

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BAC Analysis workflow

Sample collection

Blood is collected by a phlebotomist in two grey-top tubes that should contain a preservative and anticoagulant (grey top tubes are normally used in medicine for glucose-testing). Typically sodium fluoride is used as preservative. One tube is for the crime lab to test and the other is preserved for the subject’s independent testing purposes. At the crime lab, one tube is opened and the contents are poured into a clean container. A measured amount of blood and a type of alcohol (usually n-propanol) as internal standard are mixed together into a headspace vial, which is then crimp-sealed.

Sample processing

The number of samples run in a day by a forensic lab includes specimen and quality control standards can easily reach several hundreds. Sample preparation often accounts for more than twice the time spent on actual chromatography. Automate and accelerate organic volatiles determinations to increase sample turnaround and lower the cost per analysis. It is paramount that the system will be able to run many unattended analysis and safely classify and store results.

TriPlus 300 Headspace Autosampler

The Thermo Scientific TriPlus 300 Headspace Autosampler: Designed for fast startup, high productivity, and maximum flexibility for any lab analyzing organic volatiles.

  • Superior sample integrity and traceability
  • End-to-end inertness of the sample path
  • Seamless integration into multiple chromatography data systems
  • A chromatographer-friendly local user interface further enhances the system's versatility

TriPlus RSH Autosampler

With its advanced, built-in robotics, the system delivers exceptional precision, unprecedented sample handling flexibility, and reliable, weekend-long unattended operation. Ideal for high throughput lab with quick sample turnaround time.

  • Temperature-resistant syringe eliminates the need for a transfer line for direct headspace injection
  • Overlapping sample incubation capability allows higher productivity
  • Accommodates up to 300 vials facilitating high throughput need for the lab
  • Optional module enables accurate quantification of volatiles in samples with interfering matrices

GC Headspace

Typical screening for blood alcohol is done with static headspace system hooked to a gas chromatograph equipped with dual FID detectors. Headspace analyzer which is an extraction & injection system, is equipped with GC split injector to modulate the amount of sample that goes into the analytical columns. A short uncoated guard column connects to two different columns typically using different stationary phases. The columns are connected to two different FIDs, one for quantitation, and the other for confirmation.

GC Headspace schematic

Blood is a very complex biological matrix, which includes salts, proteins, lipids and other metabolites. As such, a direct analysis of blood would result in a very frequent contamination of the GC injector, leading to frequent stops in the working routines and as such very low efficiency. Headspace facilitates the extraction of volatiles and a “clean” injection in the GC system leading to minimized instrument downtime and overall short time of analysis.

TRACE 1310 Headspace GC

TRACE 1300 series Headspace GC (includes 1300 and 1310):

  • Instant connect modular GC
  • Touch screen interface provides instant access for ease of use and local control
  • Multiple detector for maximum confidence
  • Multi-language capabilities
  • Easy method development and effective feedback mechanism
  • Full audit trail to maintain chain of custody

ISQ QD Single Quadrupole GC-MS

ISQ series Single Quadrupole GC-MS (includes ISQ QD and ISQ LT):

  • Robust, reliable solution for routine lab productivity
  • Flexible configuration options to meet your lab volatile determination needs
  • Extended dynamic range to cover range of volatiles

Innovative Thermo Scientific TRACE 1300 Series GC

Achieve fast instrument setup for your analytical layout with the easy to install and swap Instant Connect modular injectors and detectors for the TRACE 1300 line of gas chromatography systems.

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Data Analysis

Simplify your analysis to just a few mouse clicks without sacrificing flexibility using Thermo Scientific Dionex Chromeleon 7.2 Chromatography Data System software. Quick, efficient peak integration with dynamic data linkage and traceability to maintain steady tracking of data at any point during processing.

Chromeleon Software benefits:

  • Dynamic linking of all data, from calibration plots to report tables and charts
  • Compliance ready data management
  • Complete multi-user chromatography management solution
  • Robust and secure file access and storage

Chromeleon CDS 7.2 Overview

Learn how to streamline your laboratory workflow with Operational Simplity and Intelligent Functionality. Chromeleon 7.2 CDS, is the first CDS to include quantitative mass spectrometry control and processing in a client/server environment.

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Additional resources