Analysis of Organophosphorus and Organochlorine Pesticides in Fruit and Vegetables Using an Agilent 8890 GC with Four Detectors

Importance of the Topic

The presence of organophosphorus and organochlorine pesticide residues in fruits and vegetables poses significant health and regulatory challenges. Sensitive and reliable analytical methods are essential to ensure food safety, comply with national standards, and support high-throughput testing in laboratories.

Study Objectives and Overview

This study aims to develop and validate a streamlined gas chromatography (GC) method following China Standard NY/T 761-2008 for simultaneous determination of organophosphorus and organochlorine pesticides in fruit and vegetable samples. The approach leverages an Agilent 8890 GC equipped with four detectors and a simplified QuEChERS sample preparation to achieve efficient, accurate, and high-throughput analysis.

Methodology and Instrumentation

The method combines a QuEChERS extraction and cleanup workflow with an Agilent 8890 GC system fitted with:

• Two flame photometric detectors (FPDs) for organophosphorus compounds
• Two electron capture detectors (ECDs) for organochlorine compounds
• An unpurged two-way capillary flow technology (CFT) splitter for simultaneous injection onto dual columns
• Columns: HP-50+ and HP-1 for organophosphorus, DB-5 and DB-17 for organochlorine

Sample extracts were split 1:1 between primary and confirmatory columns, enabling single-injection screening with selective detection. Chromatographic conditions were optimized separately for each pesticide class.

Results and Discussion

• Linearity: Calibration ranges of 0.05–0.5 mg/kg (or 0.2–2 mg/kg for low-response analytes) achieved R² > 0.992 across 54 organophosphorus and 41 organochlorine pesticides.
• Precision: Intra-day repeatability showed area RSDs < 5% (typically < 2%) at low, mid, and high spike levels in apple matrix.
• Recovery: Organophosphorus recoveries ranged from 70 to 118%; organochlorine recoveries ranged from 77 to 119%, meeting or exceeding method requirements.
• Detection Limits: MDLs were at low ppb levels (0.00003–0.05 mg/kg) using signal-to-noise criteria, surpassing reference values in NY/T 761-2008.
• Matrix Effects: Use of matrix-matched calibration significantly improved peak shape and sensitivity for polar analytes like acephate and methamidophos.
• Isomer Integration: The Area Sum function in OpenLab CDS 2.3 efficiently quantified isomeric pesticides (e.g., cyfluthrin) by summing peak areas.

Benefits and Practical Applications

• High throughput: Single injection analysis for two pesticide classes reduces instrument time and sample handling.
• Flexibility: Four-detector GC enables rapid switching between organophosphorus and organochlorine analyses without hardware changes.
• Simplicity: The QuEChERS protocol streamlines extraction and cleanup, reducing labor and solvent use while maintaining sensitivity.
• Regulatory compliance: The validated method meets China national standards and can be adapted for other pesticide monitoring programs.

Future Trends and Potential Applications

• Integration with automation platforms to further increase throughput and consistency.
• Expansion to multi-class pesticide screening by combining additional selective detectors or mass spectrometry.
• Development of green analytical techniques reducing solvent consumption and waste.
• Adaptation of the method for complex matrices beyond fruits and vegetables, such as cereals or processed foods.

Conclusion

The described Agilent 8890 GC method with four detectors and QuEChERS sample preparation provides a robust, sensitive, and efficient workflow for simultaneous analysis of organophosphorus and organochlorine pesticides in fruits and vegetables. The approach offers excellent performance metrics, regulatory compliance, and operational flexibility, making it well-suited for high-throughput food safety laboratories.

References

1. China National Standard NY/T 761-2008. Determination of Organophosphorus, Organochlorine, Pyrethroid and Carbamate Residues in Vegetables and Fruits.
2. China National Standard GB/T 19648-2006. Determination of 500 Pesticides and Metabolites Residues in Vegetables and Fruits, GC/MS Method.
3. China National Food Safety Standard GB 23200.113-2018. Determination of 208 Pesticides and Metabolites Residues in Foods of Plant Origin, GC–MS/MS Method.