Pivoting Headspace Ethanol Analysis to Accommodate Modern Day Scenarios

Helium, an inert nonrenewable gas, has historically been employed by forensic science laboratories as a carrier gas for gas chromatography methods. A global helium crisis has significantly impacted the availability of helium leaving laboratories scrambling to find alternative approaches for analytical methods. With 2022 being the eighth consecutive year of a helium deficit, negative projections and prioritization of use will inevitably leave forensic science laboratories without the essential carrier gas needed to perform analytical testing.   

For decades, the most commonly prescribed analytical technique for blood alcohol analysis in forensic toxicology laboratories has been headspace gas chromatography flame ionization detection using helium as a carrier gas. Blood alcohol analysis is arguably the most common analytical test requested in forensic toxicology laboratories and the implication of limited carrier gas supply is significant, resulting in laboratories being unable to perform the most predominate testing. The most prevalent alcohol identified is ethanol with methods also including isopropanol, methanol, and acetone.

Extensive research regarding alcohol analysis and equilibration between the liquid and gas phase was performed in the 1960s, 1970s, and even the 1980s. All optimized methods included the utilization of helium as the carrier gas. Nitrogen and hydrogen are potential alternative carrier gases based on their respective Van Deemter curves. The optimization of different carrier gasses is essential to enable laboratories to continue to perform blood alcohol analysis. With the nearly stagnant nature of research, research regarding the evaluation of critical equilibration parameters using current technology and the investigation into alternative carrier gasses is essential. Additionally, method development and validation in accordance with national standards including ANSI/ASB Standard 036, Standard Practices for Method Validation in Forensic Toxicology will further support forensic laboratories to meet the current rigorous climate of forensic toxicology.   

The goal of this research project is to develop and validate two methods for the identification and quantitation of ethanol and other volatile compounds in whole blood and additional biological matrices using headspace gas chromatography dual column flame ionization detection in accordance with ANSI/ASB Standard 036. The objectives of the project are: 1) develop two analytical methods, one using hydrogen and the other using nitrogen as the carrier gas, for the identification and quantitation of ethanol and other volatile compounds optimizing critical performance parameters; 2) validate the optimized analytical methods to meet the requirements set forth in ANSI/ASB Standard 036; 3) compare the two validated analytical methods with existing helium carrier gas methodologies using authentic biological specimens. CA/NCF