Simultaneous Analysis of Blood Alcohol and Volatile Toxic Substances Using Headspace GC-MS

Importance of the Topic

Accurate and simultaneous determination of blood alcohol and volatile toxic substances such as cyanide and azide is critical in forensic investigations of impaired driving, poisoning, and criminal incidents. Traditional methods require separate workflows and complex sample pretreatments. A streamlined headspace GC‐MS approach can improve laboratory throughput, reduce analysis time, and ensure reliable detection of both high‐level alcohol and trace toxins in a single run.

Study Objectives and Overview

This study aimed to develop and validate a headspace GC‐MS method for concurrent quantification of ethanol, hydrogen cyanide (HCN), and hydrogen azide (HN3), as well as the principal components of paint thinner (methanol, ethyl acetate, toluene) in blood matrices. Calibration standards spanning relevant forensic concentration ranges were prepared in equine hemolysate. Key performance metrics—linearity, detection limits, repeatability, and accuracy—were evaluated to assess method suitability for routine forensic analysis.

Methodology

Sample preparation involved spiking 0.5 mL of equine hemolysate with analyte standards and internal standards (2‐methyl‐1‐propanol and 2‐propanol‐d8). Acidification was achieved by adding ascorbic acid (0.1 M) and phosphoric acid (50 %) solutions directly into 20 mL headspace vials. For paint thinner components, 5 µL of stock solution was introduced. Vials were equilibrated at 60 °C for 10 min before headspace sampling.

Used Instrumentation

• Headspace sampler: HS‐20 NX
• Gas chromatograph–mass spectrometer: GCMS‐QP™2020 NX
• Column: SH‐BAC2 (30 m × 0.32 mm I.D., 1.2 µm film)
• Carrier gas: Helium, linear velocity mode (62.5 cm/s)

Results and Discussion

The total ion current chromatogram demonstrated baseline separation of HCN, ethanol, and HN3 within an 8 min runtime. Calibration curves exhibited excellent linearity (R ≥ 0.9992) across tested ranges (0.1–10 µg/mL for cyanide, 2–50 µg/mL for azide, 0.03–2 mg/mL for ethanol). Limits of detection were 0.03 µg/mL for methanol, 0.01 µg/mL for ethyl acetate, and 0.003 µg/mL for toluene. Intra‐day accuracy ranged from 99.0 % to 109.8 % for all analytes except azide (73.5 %–91.0 %) due to adsorption effects. Inter‐day repeatability over five days showed relative standard deviations below 4.1 % for cyanide, 0.9 % for ethanol, and 6.5 % for azide, confirming method robustness.

Practical Implications

This headspace GC‐MS protocol allows forensic laboratories to process blood samples for alcohol and volatile toxics in a single analytical run, significantly reducing sample handling and turnaround time. The approach minimizes carryover and maintains high sensitivity for both abundant and trace-level compounds, enhancing casework efficiency in toxicology and forensic chemistry settings.

Future Trends and Applications

Emerging developments may include integration of automated sample preparation with solid‐phase microextraction for broader analyte panels, coupling high‐resolution mass spectrometry for improved specificity, and deployment of portable GC‐MS systems for on‐site forensic screening. Advanced data processing algorithms could further streamline quantification workflows and expand application to complex biological fluids.

Conclusion

The HS‐20 NX and GCMS‐QP2020 NX combination provides a sensitive, reliable, and efficient headspace GC‐MS method for simultaneous analysis of blood alcohol and volatile toxic substances. Validation data demonstrate excellent linearity, repeatability, and low detection limits, supporting its adoption in forensic laboratories for streamlined toxicological screening and case investigations.