Thermo SOLA and SOLAμ SPE method development

Significance of the topic

Simplified and reliable sample preparation is critical in bioanalysis to ensure accurate quantification of drug candidates and biomarkers in complex biological matrices. Frit-less solid-phase extraction (SPE) formats, such as Thermo Scientific SOLA and SOLAµ, address common challenges—clogging, variability and low sensitivity—while supporting high-throughput workflows in regulated environments.

Objectives and study overview

This whitepaper presents the design features, performance advantages and generic workflows for SOLA and SOLAµ SPE products. It compares mixed-mode chemistries (WAX, SAX, WCX, SCX) and reversed-phase (HRP) formats for the isolation of acidic, neutral and basic compounds. The goal is to demonstrate robustness, reproducibility, sensitivity enhancement and ease of use in both cartridge and 96-well plate applications.

Methodology and instrumentation

Thermo Scientific SOLA and SOLAµ SPE products integrate support material and sorbent into a solid, uniform bed without loose frits. This manufacturing approach yields:

• Stable, controllable flow rates even with viscous samples
• Reproducible packing across wells, cartridges and batches
• Reduced risk of voids or channeling

A generic SPE protocol comprises conditioning (methanol, aqueous modifier), sample loading (50–500 µL at 1 mL/min), sequential washes and elution (200–500 µL organic solvent with acid/base modifier). Formats include 2 mg sorbent in 1 mL wells (SOLAµ) and 10 mg in 2 mL cartridges or plates (SOLA).

Main results and discussion

Key performance outcomes include:

• Up to 20-fold sensitivity increase compared to traditional SPE
• Successful processing of low sample volumes (≤50 µL)
• High-throughput compatibility with 96-well automation
• Low failure rates due to frit-free, uniform beds

Mixed-mode chemistries effectively retained compounds across the acidic (pKa < 2), neutral and basic (pKa > 10) spectrum, while reversed-phase HRP handled non-ionized analytes.

Benefits and practical applications

SOLA and SOLAµ SPE deliver:

• Improved assay sensitivity for trace-level bioanalysis
• Enhanced reproducibility for batch consistency
• Streamlined sample prep workflows in drug discovery, PK/PD, clinical research and QA/QC labs
• Flexibility to tailor SPE chemistry to analyte properties

Future trends and potential uses

Emerging needs in bioanalysis include miniaturization for microsampling, integration with on-line SPE-LC-MS/MS and automation-driven throughputs of thousands of samples per day. Advances in sorbent chemistries may broaden application to highly polar metabolites and large biomolecules.

Conclusion

Frit-less SOLA and SOLAµ SPE products offer a robust, high-sensitivity solution for modern bioanalytical challenges. Their reproducibility, low failure rates and compatibility with small volumes make them well suited for high-throughput drug and clinical research workflows.

Reference

Data adapted from Thermo Fisher Scientific SOLA and SOLAµ SPE application note (2020).