Increased speed and sample throughput of opioid analysis from human urine using micro-elution solid phase extraction

Significance of the topic

Reliable, high-throughput analysis of opioids in human urine is essential for clinical diagnostics, forensic testing, and therapeutic drug monitoring. Micro-elution SPE streamlines sample cleanup and improves reproducibility, meeting the demands of modern analytical laboratories.

Objectives and study overview

This study presents an optimized workflow for isolating 14 opioid compounds from urine using solid phase extraction. Comparison between conventional 10 mg SCX SPE and micro-elution 2 mg SCX SPE aims to enhance speed, reduce solvent use, and maintain analytical performance. Subsequent LC-MS/MS quantification is used to assess recovery and precision.

Methodology

• Sample pretreatment: Human urine spiked at 150 ng/mL with a mixture of opioids; diluted with 1% formic acid; vortexed and centrifuged.
• SPE protocols: 10 mg SOLA SCX versus 2 mg SOLAµ SCX in 96-well format; identical conditioning and wash steps, scaled solvent volumes, and micro-elution to streamline processing.
• Chromatography: Thermo Vanquish Horizon with Hypersil GOLD aQ column (100×4.6 mm, 3 µm); gradient elution over 15 min at 1 mL/min.
• Detection: Thermo TSQ Quantiva triple quadrupole MS operated under Chromeleon data system.

Used instrumentation

• Thermo Scientific SOLA SCX and SOLAµ SCX 96-well SPE plates
• Thermo Vanquish Horizon UHPLC system
• Thermo TSQ Quantiva triple quadrupole MS
• HyperSep vacuum manifold and UltraVap concentrator
• Hypersil GOLD aQ analytical column

Main results and discussion

Extraction recoveries ranged from 88%–99% for conventional SPE and 96%–106% for micro-elution SPE, demonstrating improved analyte elution with reduced sorbent mass. Precision was excellent for both methods (RSD <7%), with SOLAµ showing tighter reproducibility (1.4%–4.1% RSD vs 3.2%–6.2%). Solvent consumption dropped by ~1100 µL per sample and processing time decreased by 29 minutes per 96-well plate when using micro-elution. Chromatograms exhibited clear peak shapes and consistent responses.

Practical benefits and applications

• Higher throughput: elimination of evaporation and reconstitution steps accelerates sample turnaround.
• Lower solvent usage reduces costs and environmental impact.
• Robust recoveries and precision support routine use in forensic and clinical labs.

Future trends and possibilities

Micro-elution SPE can be extended to other classes of biomarkers and small molecules, allowing direct coupling with LC-MS workflows. Automation of SPE and integration with online platforms may further enhance throughput. Continued miniaturization and sorbent innovation will drive greener, more efficient sample preparation strategies.

Conclusion

The adoption of micro-elution SOLAµ SCX SPE for opioid analysis in urine delivers significant gains in speed, solvent savings, and reproducibility without sacrificing recovery. This streamlined workflow is well suited for high-throughput laboratories and aligns with current trends toward efficient, automated sample processing.

Reference

• Poster Note PN20815: LC-MS/MS Method for the Determination of 21 Opiates and Opiate Derivatives in Urine, J. Jones et al., Thermo Fisher Scientific, 2013.