Inhalants on Rtx®-BAC Plus 1 and Plus 2 Column Set

Importance of the Topic

Accurate analysis of volatile inhalants is essential in forensic toxicology, clinical diagnostics, environmental monitoring, and quality control. Reliable separation and quantitation of alcohols, ethers, ketones, and aromatic hydrocarbons support safety assessments, regulatory compliance, and investigative casework.

Objectives and Study Overview

This study evaluated the chromatographic performance of two Rtx®‐BAC Plus columns (Plus 1 and Plus 2) for simultaneous headspace‐GC analysis of 19 common inhalants. The goal was to compare retention behavior, resolution, and run times under identical sample introduction and oven programming conditions.

Methodology and Instrumentation

Sample Preparation and Introduction:

• Inhalant standards at 50 µg/mL in water.
• Headspace‐loop injection with a 50:1 split ratio, 3 min injection time, and 220 °C injector temperature.
• Tekmar HT3 headspace sampler: vial equilibration at 70 °C for 5 min, vial pressure 30 psi, transfer line and valve oven at 125 °C.

Gas Chromatography Conditions:

• Columns: 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) connected via a 5 m guard column and Y Press-Tight® connector.
• Oven program: 40 °C (4 min hold) to 120 °C at 10 °C/min.
• Carrier gas: helium at constant linear velocity (50 cm/s).
• Detector: flame ionization detector at 240 °C with 30 mL/min make-up nitrogen.

Main Results and Discussion

Both columns achieved baseline separation of 19 inhalant peaks (methanol through o-xylene). Key observations:

• Rtx®‐BAC Plus 2 exhibited uniformly shorter retention times (e.g., ethanol at 1.47 min vs. 1.69 min on Plus 1), reducing total analysis time from approximately 11 min to under 9 min.
• Critical isomeric separations such as m-, p-, and o-xylene were well resolved on both phases, with Plus 2 delivering slightly sharper peaks.
• Reproducible retention and peak shape across polar (alcohols, ethers) and nonpolar (aromatics, halogenated solvents) analytes demonstrated the columns’ broad applicability.

Benefits and Practical Applications

These phases enable rapid, reliable quantitation of inhalants in diverse matrices. Laboratories benefit from:

• Improved sample throughput due to shorter run times.
• Robust resolution for regulatory and forensic target lists.
• Versatility in analyzing polar and nonpolar volatile compounds without phase changes.

Future Trends and Potential Applications

Advances may include coupling with mass spectrometry for enhanced sensitivity and selectivity, development of ultra-fast temperature programming, and integration with automated sample preparation. Expanding applicability to emerging inhalant abuse compounds and environmental pollutant profiling are promising directions.

Conclusion

The Rtx®‐BAC Plus 1 and Plus 2 column set provides comprehensive, high-resolution separation of a broad range of inhalants. Plus 2’s thinner film delivers faster analysis while maintaining chromatographic performance, offering significant advantages for high-throughput laboratories.

Used Instrumentation

• Gas chromatograph: Agilent/HP 6890 GC with headspace sampler Tekmar HT3.
• Columns: Rtx®‐BAC Plus 1 (cat. 18004) and Plus 2 (cat. 18006) with Rxi® guard column (cat. 10039) and Universal “Y” Press-Tight® connector (cat. 20405-261).