Rtx-BAC Plus 1 and Rtx-BAC Plus 2 Columns

Significance of the topic

Accurate and rapid measurement of blood alcohol concentration is critical in clinical diagnostics, forensic toxicology, workplace safety programs, and regulatory compliance. High sample throughput, reliable separation of ethanol and related volatile compounds, and minimal interference are essential to ensure confident decision making and legal defensibility.

Study objectives and overview

This application note introduces Rtx-BAC Plus 1 and Rtx-BAC Plus 2 gas chromatography columns designed for headspace GC-FID blood alcohol analysis. The main goals are to demonstrate the columns’ selectivity, speed, robustness, and reproducibility compared to existing BAC column pairs, and to illustrate their applicability for other volatile organic compound (VOC) analyses.

Methodology and instrumentation

Analysis was performed by headspace-loop split injection (split ratio 50:1) using a Tekmar HT3 headspace concentrator and an Agilent/HP 6890 GC equipped with an FID (240 °C). Two columns were connected in parallel for dual-column confirmation: Rtx-BAC Plus 1 (30 m × 0.32 mm ID, 1.8 µm) and Rtx-BAC Plus 2 (30 m × 0.32 mm ID, 0.6 µm). Carrier gas was helium at constant flow, linear velocity ~80 cm/s at 40 °C. Oven program held at 40 °C for 3 min. Headspace conditions: 60 °C sample, 30 psi vial pressure, 5 min equilibration. A deactivated guard column was used for other VOC applications.

Main results and discussion

Rtx-BAC Plus columns achieved baseline separation of seven target compounds (methanol, acetaldehyde, ethanol, isopropanol, acetone, tert-butanol IS, and 1-propanol IS) in under 2 minutes with excellent peak symmetry (USP tailing factors for ethanol of 1.09 on Plus 2 and 1.29 on Plus 1). Competing columns exhibited coelution (acetone/tert-butanol), tailing peaks, and longer analysis times. Precision testing confirmed consistent retention and efficiency across multiple lots and conditioning at maximum isothermal temperatures (260 °C).

Benefits and practical applications

• Fast throughput: Complete dual-column confirmation in 2 minutes enhances lab productivity.
• Reliable separations: Optimized selectivity eliminates common interferences and coelutions.
• Robustness: Chemically bonded phases and rigorous quality control deliver long column lifetimes and lot-to-lot consistency.
• Versatility: The columns’ low-bleed and inert character support other VOC analyses including abused inhalants, glycols, and gamma-butyrolactone, as well as mass spectrometry applications.

Future trends and applications

Continued miniaturization of headspace-GC workflows, integration with automated sample preparation, and coupling to mass spectrometry are expected to further reduce analysis time and detection limits. Expanding column selectivities may enable broader multi-residue VOC panels for environmental monitoring, workplace air quality, and broader forensic toxicology testing.

Conclusion

Rtx-BAC Plus 1 and Plus 2 columns deliver fast, reliable, and robust blood alcohol measurements with definitive dual-column confirmation. Their superior peak shape, selectivity, and reproducibility make them ideal for high-throughput clinical and forensic laboratories, while their inertness and low-bleed properties extend their use to a wide range of volatile compound analyses.

Reference

• Restek Corporation. Advanced Technology for Fast, Reliable Measurement of Alcohol in Blood. Application Note CFSS1538A, 2018.