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

Significance of the Topic

The accurate and sensitive detection of drugs and pesticides in human blood is critical for forensic toxicology, clinical diagnostics, and environmental exposure assessment. Combining on-line gel permeation chromatography (GPC) with tandem mass spectrometry (GC-MS/MS) streamlines sample cleanup and enhances selectivity, enabling reliable quantification at trace levels.

Study Objectives and Overview

This work presents a rapid method for simultaneous determination of 20 common drugs and pesticides in human blood. A modified QuEChERS protocol was integrated with on-line GPC-GC-MS/MS to minimize sample preparation time and reduce matrix interferences while achieving low detection limits and high throughput.

Methodology and Instrumentation

Sample pretreatment:

• Aliquot 2 mL human blood.
• Extract with acetonitrile under vortex mixing.
• Add PSA, C18 sorbents and MgSO₄ for removal of proteins, lipids and pigments.
• Vortex, centrifuge and collect supernatant.
• Evaporate and reconstitute in GPC mobile phase.
• Inject into on-line GPC-GC-MS/MS system.

On-line GPC conditions:

• Column: Shodex CLNpak EV-200 (2 mm ID × 150 mm).
• Mobile phase: acetone/cyclohexane (3:7 v/v) at 0.1 mL/min.
• Oven temperature: 40 °C; injection volume: 10 µL.

GC-MS/MS conditions:

• Instrument: Shimadzu GCMS-TQ8030 with PTV injector.
• Separation: deactivated silica tubing and Rtx-5ms columns.
• Injector program: 120 °C (4.5 min) → 280 °C ramp.
• Oven program: 82 °C (5 min) → 300 °C ramp.
• Ion source: 210 °C; interface: 300 °C.

Main Results and Discussion

The method achieved recoveries of 70–120% and RSDs ≤ 5% (n=3) at spiking levels of 0.01 µg/mL. Limits of detection ranged from 0.03 to 4.4 µg/L, with quantification limits defined by S/N ≥ 10. Calibration curves showed excellent linearity (R² ≥ 0.9991) across 5–100 µg/L. Multiple reaction monitoring (MRM) chromatograms demonstrated clear separation of all 20 analytes, confirming minimal matrix interference after GPC cleanup.

Benefits and Practical Applications

• Significant reduction in sample preparation time compared to offline cleanup.
• Enhanced selectivity and lower detection limits via tandem MS.
• Satisfactory accuracy and precision for routine forensic and clinical analysis.
• Applicable to quality control of biological samples and exposure monitoring.

Future Trends and Possibilities

Advances may include integration of ultrahigh-pressure GPC for faster fractionation, coupling with high-resolution mass spectrometry for broader compound coverage, and automation of QuEChERS workflows. Expanding the method to other complex matrices (urine, tissues) and real-time monitoring platforms could further enhance its utility.

Conclusion

A streamlined on-line GPC-GC-MS/MS approach with modified QuEChERS sample preparation has been validated for simultaneous measurement of 20 drugs and pesticides in human blood. The method offers rapid, sensitive, and robust performance suitable for forensic, clinical, and environmental applications.

Used Instrumentation

• Shimadzu GPC system with Shodex CLNpak EV-200 column.
• Shimadzu GCMS-TQ8030 tandem mass spectrometer with PTV injector.
• PSA, C18 sorbents and MgSO₄ for sample cleanup.