Nitroaromatics and cyclic ketones

Significance of the Topic

Nitroaromatic compounds and cyclic ketones are common environmental pollutants arising from industrial processes, combustion by-products and pesticide degradation. Reliable analysis of these species is essential for environmental monitoring, regulatory compliance and risk assessment. Gas chromatography with flame ionization detection (GC-FID) remains a workhorse technique for routine screening due to its robustness, sensitivity and ease of operation.

Objectives and Overview of the Study

This application note demonstrates a validated GC-FID method for simultaneous separation and quantification of eight nitroaromatic and cycloketone analytes following EPA Method 8090. The primary goal is to illustrate chromatographic conditions that yield baseline resolution and reproducible retention times, enabling accurate identification and quantitation in environmental samples.

Instrumentation

• Gas chromatograph: Agilent GC system equipped with split injector and FID
• Column: Agilent VF-17ms (50% phenyl polysiloxane), 0.25 mm i.d. × 30 m, 0.25 µm film thickness
• Oven temperature program: 50 °C initial, ramp 10 °C/min to 300 °C
• Carrier gas: Helium at 70 kPa constant pressure
• Injector settings: split ratio 1:100; injection volume 1 µL
• Detector: flame ionization detector (FID)
• Standard concentration: 200 µg/mL

Key Results and Discussion

The optimized temperature program and 50% phenyl PDMS phase provided sharp, well-resolved peaks for all target compounds. Retention order was as follows:

1. Nitrobenzene
2. Isophorone
3. 1,4-Naphthoquinone
4. 1,4-Dinitrobenzene
5. 1,3-Dinitrobenzene
6. 2,6-Dinitrotoluene
7. 1,2-Dinitrobenzene
8. 2,4-Dinitrotoluene

Peak shapes were symmetrical with no significant tailing, and retention time reproducibility was within acceptable limits (<0.1% RSD). The method achieved clear separation of closely eluting isomers, demonstrating its suitability for complex matrices.

Benefits and Practical Applications of the Method

• High resolution of structurally similar nitroaromatic isomers
• Fast and reproducible analysis with a single temperature program
• Robust FID detection for quantitative screening
• Wide dynamic range suitable for trace and higher-level quantification
• Compliance with EPA Method 8090 for environmental laboratories

Future Trends and Potential Applications

• Integration with mass spectrometry for enhanced sensitivity and selectivity
• Application to soil, water and air matrices with minimal sample preparation
• Development of shorter or narrow-bore columns to reduce analysis time
• Automation and on-line sampling for high-throughput monitoring
• Green chromatography approaches using alternative carrier gases and energy-efficient ovens

Conclusion

The presented GC-FID method using an Agilent VF-17ms column meets the requirements for reliable separation and quantification of nitroaromatic compounds and cyclic ketones. Its performance aligns with EPA standards and offers a dependable tool for environmental testing laboratories.

References

Agilent Technologies, Inc. Nitroaromatics and cyclic ketones. Application Note, Agilent Technologies, Inc., 2011.