Analysis of Explosives Using a Core Enhanced Technology Accucore HPLC Column

Importance of the Topic

Explosive compounds represent serious environmental pollutants and safety hazards. Regulatory agencies such as the U.S. EPA prescribe stringent methods (EPA 8330) for their detection in soil and water. High-throughput, reliable chromatographic analysis is vital for environmental monitoring, forensic investigations, and quality control in defense and industrial settings.

Objectives and Study Overview

This application note evaluates the performance of Thermo Scientific Accucore™ core shell columns—specifically C18 and perfluorinated phenyl (PFP) chemistries—for rapid HPLC separation of a subset of EPA-listed explosives. Key goals include:

• Comparing resolution and analysis time between C18 and PFP phases.
• Assessing backpressure and method reproducibility.
• Demonstrating selectivity differences related to stationary phase chemistry.

Methodology and Instrumentation

The study employs Accucore 2.6 µm core shell particles, offering a solid core and porous outer layer to reduce backpressure while maintaining high efficiency.

• Columns:
   Accucore C18, 100 × 2.1 mm, 2.6 µm (Part No. 17126-102130)
   Accucore PFP, 100 × 2.1 mm, 2.6 µm (Part No. 17426-102130)
• HPLC System and Conditions:
   System: Thermo Scientific HPLC with UV detection at 254 nm
   Column temperature: 40 °C
   Flow rate: 0.4 mL/min
   Injection volume: 1.0 µL
   Mobile phase: Water/Methanol (60:40 v/v)
• Sample Preparation:
   Standards of 1,3,5-trinitrobenzene, 1,3-dinitrobenzene, nitrobenzene, 2,4,6-trinitrotoluene, and 2,4-dinitrotoluene were each dissolved in methanol/water (50:50), combined, and diluted to the final concentration.

Key Results and Discussion

The Accucore C18 column achieved complete separation of five explosive analytes in under 3 minutes, whereas the PFP phase required approximately 8 minutes under equivalent conditions. The C18 chemistry provided baseline resolution rapidly, while the PFP column exhibited alternative selectivity attributed to π-π interactions between the phenyl phase and nitroaromatic rings.

• Backpressure on C18: ~264 bar, significantly lower than sub-2 µm packings.
• Retention time reproducibility for 2,4-dinitrotoluene (peak 5): mean 7.86 min, SD 0.03 min, %CV 0.35.
• Peak symmetry and efficiency remained within acceptable limits (%CV < 3%).

Benefits and Practical Applications

The core shell Accucore C18 system offers:

• Ultra-fast analysis to increase sample throughput.
• Lower operating pressures for compatibility with standard HPLC equipment.
• Robust, high-efficiency separations suitable for routine environmental and forensic testing.
• Complementary selectivity of PFP phase for confirmatory analysis of nitroaromatic compounds.

Future Trends and Prospects

Advances in core shell particle technology and column chemistries will further reduce analysis times and improve resolution. Potential developments include:

• Integration with mass spectrometry for enhanced sensitivity and compound identification.
• Automated methods for on-site environmental screening.
• Tailored phases for emerging contaminants and novel energetic materials.

Conclusion

The Thermo Scientific Accucore C18 column delivers rapid, high-efficiency separation of key explosive compounds in under 3 minutes, outperforming a PFP phase in speed while offering lower backpressure and excellent reproducibility. The PFP column provides distinct selectivity advantageous for confirmation. This approach supports high-throughput environmental and forensic analysis.

References

Aspey S. Analysis of Explosives Using a Core Enhanced Technology Accucore HPLC Column. Thermo Fisher Scientific Application Note ANCCSCETEXPLO (2011). EPA Method 8330: Nitroaromatics and Nitramines by HPLC.