Extraction of Opiates from Whole Blood Using ISOLUTE® SLE+ Prior to GC/MS Analysis

Significance of the topic

Opiate analysis in whole blood is critical for forensic toxicology, clinical diagnostics and therapeutic drug monitoring. Reliable quantification of morphine, codeine and related compounds ensures accurate interpretation of drug exposure, compliance assessment and postmortem investigations.

Objectives and Overview of the Study

This application note describes a streamlined procedure for extracting opiates from human whole blood using ISOLUTE SLE+ supported liquid extraction (SLE) prior to gas chromatography–mass spectrometry (GC/MS) analysis. Key goals include achieving high recoveries, low limits of quantitation and compatibility with multiple drug classes without protein precipitation.

Methodology

The procedure comprises:

• Sample Pre-treatment: Add internal standard mix to 1 mL blood, equilibrate, then dilute with 1 mL 1 % ammonium hydroxide.
• Sample Loading: Apply 750 µL of pre-treated blood to ISOLUTE SLE+ 1 mL column; allow 5 min absorption.
• Analyte Extraction: Elute twice with 2.5 mL dichloromethane (DCM) each; alternative solvent MTBE is acceptable for non-chlorinated extraction and multi-class recovery.
• Post Elution: Evaporate under nitrogen or air; reconstitute first in ethyl acetate, then in BSTFA + 1 % t-BDMCS; heat at 70 °C for 30 min for derivatization.

Used Instrumentation

• GC: Agilent 7890A with QuickSwap inlet, DB-5 column (30 m × 0.25 mm × 0.25 µm), splitless injection at 250 °C.
• MS: Agilent 5975C, electron impact source at 230 °C, quadrupole at 150 °C, operated in SIM mode.
• Evaporation: TurboVap LV or Biotage SPE Dry concentrator for solvent removal.

Main Results and Discussion

The method delivered:

• Recoveries above 85 % for all opiates, with RSDs below 10 % using either DCM or MTBE.
• Lower limits of quantitation between 50 and 100 ng/mL depending on analyte.
• Excellent linearity (r2 = 0.9967–0.9998) across 10–500 ng/mL calibration range.

Chromatograms exhibited clear baseline separation of eight opiate targets and their deuterated analogues, with no emulsion issues and minimal matrix interference.

Benefits and Practical Applications

This SLE+ approach offers:

• Reduced sample handling and elimination of protein precipitation.
• High throughput compatible with 96-well formats and pressure manifolds.
• Cost-effective extraction with consistent performance for forensic and clinical laboratories.

Future Trends and Potential Applications

Advances may include automation on robotic platforms, expansion to multi-analyte panels (e.g., synthetic opioids, novel psychoactive substances) and adoption of greener extraction solvents. Integration with high-resolution mass spectrometry could further enhance sensitivity and specificity.

Conclusion

The described ISOLUTE SLE+ protocol provides a robust, efficient solution for opiate extraction from whole blood, yielding clean extracts, reliable quantitation and adaptability to diverse laboratory workflows.