Contract Laboratory Program (CLP) Pesticide Analysis with 0.18 mm ID High-Efficiency GC Columns Utilizing Helium Carrier Gas

Significance of the Topic

Contract Laboratory Program (CLP) pesticide analysis is essential for environmental monitoring and regulatory compliance. High-efficiency gas chromatography methods that reduce analysis time and maintain resolution are crucial for laboratories handling large sample volumes.

Objectives and Study Overview

This study evaluates 20 m × 0.18 mm × 0.18 µm high-efficiency GC columns (DB-17ms for primary analysis and DB-XLB for confirmation) with helium carrier gas. It demonstrates method translation from an existing hydrogen-based CLP pesticide protocol to helium, aiming to shorten run times and preserve separation quality for 22 target organochlorine pesticides.

Instrumentation

• Agilent 6890N gas chromatograph with dual micro-electron capture detectors (µECD)
• Agilent 7683B autosampler
• Columns: DB-17ms and DB-XLB, 20 m × 0.18 mm × 0.18 µm
• 5 m × 0.25 mm id retention gap with Y-splitter assembly
• Helium carrier gas (constant flow ~49.5 cm/s at 120 °C)

Methodology

CLP pesticide standards were diluted in 2,2,4-trimethylpentane and introduced via a pulsed splitless 0.5 µL injection (35 psi, 250 °C inlet). A retention gap and Y-splitter directed the split flow to both analytical columns. The original hydrogen-carrier GC method parameters and new column dimensions were entered into Agilent’s method translation software to generate helium-based conditions. The temperature program ranged from 120 °C to 300 °C with multiple ramps.

Results and Discussion

The translated helium method achieved baseline separation of all 22 pesticides on the DB-17ms column in 11 minutes—a 35 % reduction compared to standard 0.32 mm columns. The DB-XLB confirmation column replicated elution order and degree of separation, with a partially resolved chlordane/endosulfan I triplet remaining acceptable for confirmation. Detector sensitivity enabled on-column loadings down to 0.4 pg per component, and a linear response over 1.6–40 ng/mL suggested an even broader dynamic range is attainable.

Benefits and Practical Applications

• 35 % faster analyses versus wider bore columns
• Full compatibility with existing GC systems and helium carrier gas
• Effortless conversion of hydrogen-based methods using translation software
• Extended column life and reduced maintenance via retention gap protection
• High sensitivity supporting trace-level pesticide quantitation

Future Trends and Potential Applications

Future work may expand dynamic range, optimize separation of challenging analyte groups, and adapt method translation to other carrier gases and column chemistries. Integration of software-driven workflows and automation will further enhance throughput in environmental and industrial laboratories.

Conclusion

High-efficiency 0.18 mm id GC columns operated with helium carrier gas, combined with method translation software, provide rapid, sensitive, and robust CLP pesticide analysis. This approach offers significant time savings, straightforward implementation on standard GC instrumentation, and reliable performance for confirmation protocols.

References

1. Agilent Technologies. Method Translation Software. Available at http://www.chem.agilent.com/cag/servsup/usersoft/files/GCTS.htm
2. George, C. Rapid Analysis of CLP Pesticides Using High-Temperature DB-35ms and DB-XLB Columns. Application Note 5988-4973EN, Agilent Technologies, 2001.
3. Wool, L., Decker, D. Practical Fast Gas Chromatography for Contract Laboratory Program Pesticide Analysis. Journal of Chromatographic Science, Vol. 40, 2002.
4. Chang, I. L., Klee, M. S., Murphy, J. Validation Analysis of EPA CLP Target Organochlorine Pesticides with the Agilent 6890 Series GC and Micro-ECD. Application Note 5966-3742E, Agilent Technologies, 1998.