Automated Disposable Pipette Extraction - DPX

Importance of Topic

Disposable Pipette Extraction (DPX) addresses the critical demand for rapid, sensitive, and reproducible sample preparation in modern analytical laboratories. By combining solid-phase extraction with single-use pipette tips, DPX streamlines trace-level analyses in clinical toxicology, forensic science, environmental monitoring, and pharmaceutical research.

Study Objectives and Overview

This summary reviews the principles and performance of DPX technology, emphasizing its speed, automation potential, and compatibility with GC/MS and LC/MS platforms. Applications include drug screening, therapeutic drug monitoring, pesticide residue analysis, and comprehensive metabolite profiling.

Methodology and Instrumentation

DPX employs pipette tips preloaded with loosely packed sorbent mixed directly with the sample. Key steps are:

• Optional conditioning of the sorbent with solvent.
• Aspiration of the sample into the tip for direct sorbent contact.
• Turbulent air-bubble mixing to suspend sorbent in the sample for efficient extraction.
• Rapid discharge of the extract, typically within 30 seconds.
• Optional wash steps before elution of target analytes into a vial.

Automation is achieved using the GERSTEL MPS 2 PrepStation and MAESTRO software, which integrates DPX with Agilent ChemStation methods for seamless GC/MS and LC/MS operation.

Main Results and Discussion

DPX eliminates lengthy conditioning by equilibrating and eluting analytes in seconds. Recoveries approach 100% for basic compounds, with relative standard deviations below 15% across diverse drug panels. Low detection limits are attained from less than 250 µL of blood or urine, leveraging minimal elution volumes and large-volume injections to bypass solvent evaporation. Representative outcomes include:

• GC/MS screening of 13 drugs of abuse in whole blood (250 µL) with average RSDs between 2% and 14%.
• THC and metabolite analysis in blood after protein precipitation, DPX-RP cleanup, and in-inlet derivatization, yielding clear chromatograms with no additional evaporation.
• Automated benzodiazepine profiling in urine following enzymatic hydrolysis and DPX cleanup, with on-column MTBSTFA derivatization and excellent sensitivity.
• DPX-LC/MS/MS quantitation of 40 opioid, stimulant, and sedative drugs in urine, using dynamic MRM on an Agilent 6410 TripleQuad and achieving recoveries above 60% for all targets.

Benefits and Practical Applications

DPX accelerates sample preparation, enabling parallel processing during chromatographic runs for optimal throughput. Disposable tips reduce carryover, and low solvent consumption aligns with green chemistry goals. The technique supports a broad range of matrices and analyte classes, making it ideal for high-throughput clinical and forensic laboratories, environmental residue testing, and routine QA/QC analyses.

Future Trends and Potential Applications

Advances may include integration with robotic platforms for fully unattended workflows, real-time feedback loops for dynamic method optimization, extension to challenging matrices (e.g., foods, soils), and development of eco-friendly sorbents. Coupling DPX with compact mass spectrometers could enable decentralized or point-of-care testing solutions.

Conclusion

Disposable Pipette Extraction offers a transformative SPE approach, combining speed, reproducibility, and automation with minimal solvent use. Its compatibility with major analytical platforms and broad application range positions DPX as a key technique for laboratories seeking high throughput and low detection limits.