Fast Analysis of Organochlorine Pesticides Standard Using Conventional GC Instrumentation

Significance of the topic

In routine environmental and food safety laboratories high sample throughput and reduced analysis times are critical. Gas chromatography methods for organochlorine pesticides often require long run times to achieve adequate resolution impacting productivity. Adapting conventional GC systems with fast GC columns can deliver rapid separations without sacrificing chromatographic performance.

Objectives and Study Overview

This application note evaluates the performance of a fast GC column with 0.15 mm internal diameter compared to a standard 0.25 mm column for the analysis of an organochlorine pesticide standard mix following EPA Method 8081. The study aims to demonstrate method transfer to a Thermo Scientific TraceGOLD TG-5SilMS fast GC column and to assess reductions in analysis time resolution and reproducibility.

Methodology and Instrumentation

A working OCP standard solution 50 µg/mL in hexane was used. Three GC methods were compared:

• Method I – Standard column 30 m x 0.25 mm x 0.25 µm 1.2 mL/min He split 30:1 1 µL injection temperature program yielding 15.17 min run time
• Method II – Fast GC column 20 m x 0.15 mm x 0.15 µm 0.6 mL/min He split 30:1 0.5 µL injection optimized gradient giving 10.91 min run time
• Method III – Fast GC column 20 m x 0.15 mm x 0.15 µm 1.0 mL/min He split 30:1 0.5 µL injection accelerated gradient yielding 8.08 min run time

Instrumental parameters:

• Thermo Scientific TRACE GC Ultra with split splitless injector at 280 °C
• Flame ionization detector at 300 °C with air 350 mL/min hydrogen 35 mL/min nitrogen 30 mL/min
• Data processed using Xcalibur software

Key Results and Discussion

Method II reduced run time by approximately 30% compared to Method I with only a minor 4% loss in resolution. By increasing linear velocity in Method III run time decreased by around 50% relative to Method I while achieving a slight 7% improvement in resolution. Column head pressure increased from 190 kPa to 348 kPa and to 472 kPa but remained within the 1000 kPa system limit. Six replicate injections showed excellent retention time reproducibility RSD less than 0.15 percent across all methods.

Benefits and Practical Applications

• Up to 50% faster analysis without modifying system hardware
• Maintained or improved resolution for critical OCP compounds
• High reproducibility supports compliance with EPA Method 8081 requirements
• Increased laboratory throughput and reduced resource consumption

Future Trends and Opportunities

Fast GC approaches can be extended to other pesticide classes and environmental analytes. Combining fast columns with mass spectrometry detection may resolve coeluting peaks. Further integration with multidimensional GC and advanced detectors can enhance selectivity and speed. Automation and ultrafast programming may drive next generation high throughput analyses.

Conclusion

Transferring an EPA Method 8081 OCP analysis to a 20 m x 0.15 mm fast GC column significantly reduces run times by up to 50% without compromising resolution or reproducibility. Adjusting column dimensions carrier gas flow and temperature gradients allows high speed separations on conventional GC systems.

References

None cited.