Simultaneous Determinations of 20 kinds of common drugs and pesticides in human blood by GPC-GC-MS/MS

Importance of the Topic

Rapid and reliable detection of multiple drugs and pesticides in human blood is vital for clinical diagnosis, forensic investigations and quality control in environmental and food safety. Conventional sample preparation can be time consuming and prone to matrix interferences. On-line gel permeation chromatography coupled with gas chromatography tandem mass spectrometry (GPC-GC-MS/MS) streamlines cleanup and enhances selectivity, making large-scale and high-throughput analyses more practical.

Objectives and Study Overview

The main goal was to establish a fast, sensitive and robust method for the simultaneous determination of 20 common drugs and pesticides in human blood. A modified QuEChERS protocol was applied for sample extraction and cleanup, followed by on-line GPC-GC-MS/MS analysis to achieve low detection limits and high repeatability.

Methodology

Sample pretreatment steps:

• Aliquot 2 mL of whole blood and add acetonitrile for protein precipitation.
• Vortex and add PSA, C18 and MgSO₄ to remove lipids, proteins and pigments.
• Centrifuge, collect supernatant, evaporate to dryness and reconstitute in mobile phase.

Chromatographic cleanup: on-line GPC using acetone/cyclohexane (3:7, v/v) at 0.1 mL/min through a Shodex CLNpak EV-200 column maintained at 40 °C.

Used Instrumentation

Key instrument details:

• GPC System: Shodex CLNpak EV-200 column (2 mm I.D. × 150 mm L.), acetone/cyclohexane mobile phase.
• GC-MS/MS: Shimadzu GCMS-TQ8030 with a PTV injector, Rtx-5ms analytical column (30 m × 0.25 mm × 0.25 μm).
• Injector program: 120 °C hold, ramp at 80 °C/min to 280 °C.
• Oven program: 82 °C for 5 min, ramp at 8 °C/min to 300 °C.
• Ion source 210 °C, interface 300 °C.

Key Results and Discussion

Method performance:

• Linearity: correlation coefficients ≥ 0.9991 across 5–100 μg/L.
• Recoveries: 70–120% for all 20 analytes at 0.01 μg/mL spiking level.
• Precision: RSD ≤ 5% (n=3).
• Limits of detection: 0.03–4.4 μg/L; limits of quantification: defined at S/N ≥ 10.

MRM chromatograms demonstrated clear separation and low matrix background after GPC cleanup, confirming effective removal of proteins, lipids and pigments.

Benefits and Practical Applications

This approach offers:

• Rapid sample preparation with on-line cleanup reduces hands-on time.
• Broad applicability to a diverse set of analytes in complex biological matrices.
• Enhanced sensitivity and selectivity for trace-level detection.
• Suitability for forensic toxicology, clinical pharmacology and regulatory compliance testing.

Future Trends and Opportunities

Potential directions include:

• Extending the panel to additional pharmaceuticals and emerging contaminants.
• Application to other biological fluids (urine, saliva) and tissues.
• Integration with high-resolution mass spectrometry for non-target screening.
• Miniaturization and automation of QuEChERS workflows for higher throughput.

Conclusion

A combined QuEChERS and on-line GPC-GC-MS/MS method has been validated for the simultaneous analysis of 20 drugs and pesticides in human blood. The method is simple, fast, reliable and meets rigorous validation criteria, demonstrating strong potential for routine use in forensic and clinical laboratories.