Improved Sample Pretreatment Using Offline Supercritical Fluid Extraction

Significance of the Topic

The efficient extraction of target compounds from solid matrices is a critical step in modern separation analysis workflows, impacting sensitivity, reproducibility, and environmental footprint. Supercritical fluid extraction (SFE) addresses limitations of traditional solvent-based methods by offering rapid, automated pretreatment with reduced solvent consumption and minimized thermal degradation of labile analytes.

Aims and Overview of the Study

This technical report introduces the Nexera UC SFE pretreatment system and demonstrates its applicability for automated offline SFE. Two application examples—extraction of d-α-tocopherol (vitamin E) from dietary supplements and multi-residue pesticide analysis in brown rice—illustrate system performance in terms of repeatability, recovery, and throughput.

Methodology and Instrumentation

The Nexera UC SFE system automates four key steps: vessel loading and heating; static extraction; dynamic extraction through the sample bed; and analyte trapping, elution, and fraction collection. Supercritical CO2, optionally modified with methanol, serves as the primary solvent. Extraction parameters (temperature, pressure, modifier concentration) are user-configurable via the LabSolutions software interface. Post-extraction, analytes are trapped on an ODS column and eluted with organic solvent prior to analysis by SFC, GC/MS/MS, or other techniques.

Used Instrumentation

• Nexera UC SFE Pretreatment System with rack changer (max. 48 vessels)
• SFC with COSMOSIL Cholester column and UV-VIS detection
• GC/MS/MS with Rxi-5Sil MS column in MRM mode

Main Results and Discussion

In the vitamin E study, six replicate extractions of d-α-tocopherol from supplement capsules yielded an average recovery of 103.9–106.4% with RSD below 1.6%. In the pesticide study, 301 analytes spiked into brown rice were recovered at 70–120% with RSD values below 10% for representative compounds. Both use-cases confirmed high reproducibility, low solvent use, and rapid processing compared to Soxhlet or conventional solid-liquid methods.

Benefits and Practical Applications of the Method

• Automated, high-throughput pretreatment of up to 48 samples
• Reduced solvent consumption and operational costs
• Mild extraction conditions that preserve thermolabile compounds
• Compatibility with multiple downstream analytical techniques

Future Trends and Possibilities

Advances in SFE may include integration with online separation systems for continuous workflows, expanded use of polarity-modifying additives to target highly polar analytes, and miniaturization of extraction vessels for microscale analyses. Coupling SFE with high-resolution MS and multidimensional chromatography could further broaden its application in metabolomics, environmental monitoring, and quality control.

Conclusion

The Nexera UC SFE pretreatment system offers a robust, automated solution for extracting diverse analytes from solid samples with high efficiency, reproducibility, and environmental sustainability. Its flexible configuration and compatibility with various analytical platforms position SFE as a valuable pretreatment technique for modern analytical laboratories.