Low Calibration Limit Research for Multiresidue Pesticides in Milk Using the Agilent 8890/7010B and 7890B/7000C Triple Quadrupole GC/MS Systems

Significance of the topic

Ensuring the safety of milk and dairy products is critical due to stringent regulatory limits on pesticide residues. Milk has complex matrix effects and often requires detection at ultra low levels below those set for fruits and vegetables. Advanced analytical workflows combining effective cleanup and highly sensitive instrumentation are essential to meet these demands.

Objectives and Study Overview

This study compares two triple quadrupole GC MS systems from Agilent Technologies for multiresidue pesticide analysis in milk. The goal is to evaluate linearity and low calibration limits using the 7890B 7000C platform with an extractor source and the 8890 7010B platform with a high efficiency source.

Methodology and Instrumentation

• Sample preparation follows a modified QuEChERS Captiva EMR lipid protocol with acetonitrile extraction, magnesium sulfate drying, lipid removal via EMR cartridge, and a 2.5-fold dilution factor
• Matrix matched calibration standards are prepared by spiking blank milk extracts to achieve final concentrations from 0.4 to 200 ng per milliliter
• GC conditions include an HP 5ms UI column and a temperature program from 60 to 310 degrees Celsius
• The 7890B 7000C system uses an extractor electron ionization source while the 8890 7010B employs a high efficiency source yielding up to twenty times more ions
• MS MS acquisition uses dynamic MRM with automatic method setup and retention time locking for reproducibility

Main Results and Discussion

• Linearity from 1 to 500 ng per milliliter was achieved for most of the 118 target pesticides with correlation coefficients of 0.99 or higher on both systems
• The 8890 7010B system reached a low calibration limit of 1 ng per milliliter for approximately 60 percent of the analytes, compared to only 10 percent on the 7890B 7000C system
• Statistical evaluation shows that 28 percent of compounds had two to four times lower calibration limits on the 7010B, 39 percent had five times lower, 15 percent ten times lower, and 4 percent more than twenty times lower; 13.5 percent were equivalent
• Signal to noise improvements were notable, for example chlordane oxy yielded SN of 32 with the high efficiency source versus 7.4 with the extractor, and phosmet produced SN of 23.1 versus 5

Advantages and Practical Applications

The workflow delivers ultratrace detection sensitivity and robust cleanup, automated MRM method creation, broad pesticide coverage, and compliance with tight regulatory limits, making it suitable for routine QA QC laboratories in dairy safety testing.

Future Trends and Opportunities

Further developments may include extending methods to additional food matrices, achieving even lower detection thresholds, integrating with liquid chromatography MS MS platforms, deploying portable GC MS for field testing, and applying artificial intelligence to data processing and interpretation.

Conclusion

Both GC MS MS platforms meet regulatory requirements for milk testing, but the 8890 7010B system with a high efficiency source offers superior sensitivity for ultra low residue analysis, enhancing confidence in food safety monitoring.

References

1. GB 2763-2019 National food safety standard Maximum residue limits for pesticides in food
2. Yang X Zhang YJ Zhang ZM Analysis of multiclass multiresidue pesticides in milk using Captiva EMR lipid with LC MS MS and GC MS MS application note 5994-2038EN 2020
3. Andrianova AA Westland JL Quimby BD Quantitation of pesticides in strawberries at tolerance levels established by EPA application note 5994-0799EN 2019