Determination of Drugs in Human Blood via Bidirectional Solid Phase Extraction

Significance of the topic

The bidirectional SPE technique offers a contamination-free, automated approach for extracting drugs and toxicants from forensic blood samples, preserving sample integrity and ensuring reliable forensic results.

Objectives and Study Overview

The study aimed to develop and validate an automated bidirectional solid-phase extraction (BD-SPE) method using a FREESTYLE SPE system to process human blood samples in forensic investigations without risking cross-contamination.
It targeted a wide range of 162 analytes including common drugs, pharmaceuticals, and synthetic cannabinoids.

Methodology

• Sample preparation: Dilution of 0.5 mL blood with water, vortex mixing, centrifugation, and transfer of supernatant for SPE.
• Bidirectional SPE loading: Reversed sample introduction via Luer tip into 3 mL Oasis HLB cartridges, preventing sample entry into the system.
• SPE steps: Cartridge conditioning, washing, drying, and elution; combined eluates evaporated and reconstituted in HPLC solvent.
• LC-MS/MS analysis: Agilent 1290 UPLC coupled to Agilent 6460 Jetstream Triple Quadrupole MS, C18 column, gradient elution with ammonium acetate/formic acid and methanol.

Used Instrumentation

• FREESTYLE BASIC and SPE robotic platform
• 3 mL Oasis HLB SPE cartridges
• Agilent 1290 UPLC and 6460 Jetstream Triple Quadrupole MS
• Nitrogen blow-down evaporator

Key Results and Discussion

Recovery rates for 162 analytes ranged from 4.2 % to 122 %, with repeatability (within-day RSD) between 0.8 % and 10 % and reproducibility (5-day RSD) from 2.3 % to 18 %. No cross-contamination was detected at a 10 ppm spike level in subsequent blanks, confirming method robustness.

Benefits and Practical Applications

• Minimal sample alteration preserves analyte profiles in post-mortem and antemortem blood.
• Broad applicability to acidic, neutral, and basic compounds including illicit drugs and pharmaceuticals.
• Automation reduces hands-on time and eliminates cross-contamination risk.

Future Trends and Opportunities

Integration with GC-MS/MS via solvent exchange and derivatization could broaden analyte coverage. Further automation and multiplexing may enhance throughput in forensic laboratories. Advances in MS technology and data analysis could improve sensitivity and expand screening libraries.

Conclusion

The BD-SPE approach on the FREESTYLE platform delivers a reliable, contamination-free, and efficient sample preparation method for comprehensive forensic blood analysis, meeting stringent performance criteria for routine screening.