Fast GC-ECD Analysis of Organochlorine Pesticides

Significance of the Topic

Rapid and reliable detection of organochlorine pesticides (OCPs) is critical for environmental monitoring, food safety and regulatory compliance. Traditional gas chromatography methods require long analysis times and large sample volumes, limiting laboratory throughput and delaying decision making. The development of fast GC techniques coupled with electron capture detection (ECD) addresses these challenges by reducing runtime while maintaining sensitivity and resolution.

Objectives and Study Overview

• Develop a fast GC-ECD method for simultaneous determination of 23 organochlorine pesticide residues.
• Compare conventional and fast GC approaches in terms of analysis time, peak resolution and detection limits.
• Demonstrate applicability on real food matrices using a standardized multiresidue extraction protocol.

Methodology and Instrumentation

• Sample Preparation: Multiresidue extraction following the S19 protocol and DIN EN standards for pesticide analysis in food.
• Conventional GC-ECD Conditions: RTX-5 column (30 m x 0.25 mm ID x 0.25 µm film), temperature ramp from 100 °C to 280 °C, hydrogen carrier gas at linear velocity of 23 cm/s, injection 1 µL split 40:1.
• Fast GC-ECD Conditions: Narrow-bore columns (8.9 m x 0.1 mm ID x 0.1 µm film or 10 m x 0.18 mm ID x 0.4 µm film), initial temperature 80 °C, rapid heating rates up to 60 °C/min, hydrogen carrier gas at 100–120 cm/s, splitless or high-pressure injection (up to 400 kPa).
• Detector Settings: ECD with make-up gas flow of 80 mL/min, filter time constant of 20 ms, sampling frequency of 63–250 Hz to ensure sufficient data points across narrow peaks.

Main Results and Discussion

The conventional method achieved separation of 23 OCPs in approximately 29 minutes. In contrast, the fast GC approach reduced the retention time of p,p-DDD to below 3.6 minutes and completed the full pesticide profile in under 5 minutes. Peak widths at half height were around 0.5 s, demonstrating sharp, well-resolved signals. Split injection provided detection limits near 0.1 ppb (signal-to-noise ratio 440:1), while splitless mode on narrow-bore columns achieved limits down to 0.01 ppb. Analysis of grape extract spiked with chlorpyrifos and cypermethrin confirmed the method’s applicability, yielding quantitation at sub-ng/kg levels.

Benefits and Practical Applications

• High Throughput: Runtime reduced by up to 80 %, enabling more samples per day.
• Enhanced Sensitivity: Narrow peaks improve signal-to-noise ratios without sacrificing resolution.
• Routine Screening: Suitable for environmental monitoring, food safety labs and regulatory testing.
• Resource Efficiency: Lower carrier gas consumption and faster column recycling.

Future Trends and Possibilities

Advancements in microbore column technology, ultra-fast temperature programming and combined detectors (e.g., ECD–MS interfaces) will further accelerate pesticide analysis. Integration with automated sample preparation and data processing software will streamline workflows. Development of multianalyte screening platforms covering broader classes of contaminants is expected to grow.

Conclusion

Fast GC-ECD on modern instruments like the Shimadzu GC-2010 offers a compelling solution for rapid, sensitive and reliable determination of organochlorine pesticides. The method significantly reduces analysis time, lowers detection limits and maintains high chromatographic performance, making it ideal for high-throughput laboratories.

Pouzita instrumentace

• Gas chromatograph: Shimadzu GC-2010
• Detector: Electron capture detector (ECD-2010)
• Columns: RTX-5 (30 m x 0.25 mm x 0.25 µm); CPsil narrow-bore (8.9 m x 0.1 mm x 0.1 µm); RTX-5 (10 m x 0.18 mm x 0.4 µm)
• Carrier gas: Hydrogen at 23–120 cm/s
• Injection: Split (40:1) and splitless modes; high-pressure pulses up to 400 kPa
• Detector settings: Make-up gas 80 mL/min; filter time constant 20 ms; sampling frequency 63–250 Hz

Reference

• [1] Van Es A. High Speed Narrow Bore Capillary Gas Chromatography; Hüthig: Heidelberg, 1992.
• [2] Baier H-U., Mondello L. Die schnelle Gaschromatographie in der Lebensmittelanalytik; Behrs Verlag, 2004.
• [3] Hinshaw J. Liquid and Gas Chromatography, LCGC 2002, Vol. 15, p. 152.