Fast Analysis of Aromatic Solvent with 0.18 mm ID GC column

Importance of the Topic

Aromatic solvents such as benzene, toluene and xylenes are widely used in the chemical and petrochemical industries. Accurate purity determination of these compounds is essential for quality assurance and regulatory compliance. Traditional GC methods specified by ASTM provide reliable results but often require long analysis times and multiple column types for different solvents.

Objectives and Study Overview

This application note evaluates the use of high-efficiency 0.18 mm internal diameter GC columns to develop a single, rapid method for aromatic solvent purity analysis. The goals are:

• Combine multiple ASTM methods into one unified GC method
• Compare conventional 0.32 mm id columns to 0.18 mm id high-efficiency columns
• Optimize carrier gas choice (helium, hydrogen, nitrogen) to minimize run time
• Validate performance with calibration standards and a real sample matrix

Methodology and Instrumentation

Instrumentation:

• Agilent 6890N and 7890 GC systems with split/splitless inlets
• Agilent 7683 Automatic Liquid Sampler
• Flame ionization detectors at 250 °C
• Agilent ChemStation for data acquisition and Method Translation Software

Columns and Conditions:

• Conventional column: 60 m × 0.32 mm × 0.50 µm HP-INNOWax, helium at 20 psi
• High-efficiency column: 20 m × 0.18 mm × 0.18 µm HP-INNOWax, helium at 33 psi
• Oven programs optimized via Method Translation Software in “translate only,” “best efficiency,” and “fast analysis” modes
• Injection volumes 0.2–1.0 µL with split ratios up to 600:1

Main Results and Discussion

Run Time Reduction:

• Conventional method run time: 23 min
• High-efficiency method: 7 min (3× faster) when replicating original program
• Optimized fast method: 5 min (4.6× faster) with baseline resolution maintained

Carrier Gas Effects:

• Nitrogen carrier increased run time to ~60 min (vs. 23 min with helium)
• Hydrogen carrier on 0.32 mm column provided ~1.7× speedup over helium
• Hydrogen carrier on 0.18 mm column reduced run time from 5 min to 3 min while preserving resolution

Calibration Standards:

• ASTM D2306 (C8 aromatics): 4.5× run time reduction with high-efficiency column; comparable resolution
• ASTM D2360, D3797, D3798, D4492: all key analytes separated within 4–5 min on 0.18 mm column

Real Sample Validation:

• Integrated petrochemical aromatic solvent sample showed comparable separation of benzene, toluene, ethylbenzene, xylenes and impurities
• High-efficiency column achieved over 3× run time reduction vs. conventional column

Benefits and Practical Applications

The high-efficiency 0.18 mm id GC column method enables:

• Significant increase in sample throughput and lower cost per sample
• Single unified method covering multiple aromatic solvents
• Compatibility with existing GC systems—no hardware modification needed
• Reduced carrier gas consumption

Future Trends and Applications

Further developments may include:

• Expanded use of hydrogen as a carrier gas for faster analyses
• Integration with automated sample preparation for high-throughput laboratories
• Exploration of sub-0.18 mm id columns when instrumentation allows
• Application to broader volatile and semi-volatile compound classes

Conclusion

High-efficiency 0.18 mm id GC columns deliver dramatic reductions in analysis time for aromatic solvent purity testing without sacrificing resolution or sensitivity. By combining multiple ASTM methods into one optimized program and selecting an appropriate carrier gas, laboratories can achieve 3–5× improvements in throughput on standard GC platforms.

Reference

1. Annual Book of ASTM Standards, Vol. 6.04, ASTM, West Conshohocken, PA, USA
2. McCurry J. D., A Unified Gas Chromatography Method for Aromatic Solvent Analysis, Agilent Technologies, 2007
3. Zhou Y., A Unified Method for the Analysis of Aromatic Solvent Using the Agilent 6820 GC System, Agilent Technologies, 2008
4. ASTM Method D3797, Standard Test for Analysis of o-Xylene, ASTM, 2007
5. Lynam K., Zou Y., A Faster Solution for Unified VOC Analysis with 0.18 mm ID GC Columns, Separation Times 20(5), 2007