GERSTEL Twister®

Importance of the Topic

The accurate and efficient extraction of organic compounds from aqueous and complex matrices is a cornerstone of modern analytical chemistry. Stir Bar Sorptive Extraction (SBSE) and its variants offer solvent-free, high-sensitivity approaches for sample preparation, reducing labor and eliminating extensive cleanup steps. The GERSTEL Twister® family and associated tools address key challenges in environmental monitoring, food and beverage quality control, and extractables and leachables analysis, making these technologies vital for laboratories seeking robust, reproducible and high-throughput workflows.

Objectives and Overview

This whitepaper introduces GERSTEL’s Twister® products and methods, including standard SBSE, Solvent Assisted SBSE (SA-SBSE), Multi-Stir Bar Sorptive Extraction (mSBSE) using the Twicester® accessory, and the Twister Back Extraction (TBE) approach. It outlines how each technique enhances analyte recovery across a broad polarity range, improves throughput via multi-position extraction and integrates seamlessly with thermal desorption–GC/MS and LC/MS workflows.

Methodology and Instrumentation Used

Key techniques and instruments described include:

• SBSE with PDMS and EG/Silicone Twister phases for apolar and polar analytes
• SA-SBSE using Flex Twister® pre-wetted with solvents to boost extraction of log Kow 1–2 compounds
• Multi-Stir Bar Sorptive Extraction (mSBSE) enabled by the magnetic Twicester® clip for simultaneous use of multiple Twisters
• Twister Back Extraction (TBE) combining SBSE sorption with solvent elution for high-boiling or thermally labile analytes
• GERSTEL Tube Conditioner (TC 2) for conditioning Twisters and TD tubes
• Thermal Desorption Unit (TDU 2) coupled to GERSTEL Cooled Injection System (CIS) for automated desorption and cryofocusing
• GERSTEL MAESTRO software for sequence control, PrepBuilder workflows and multi-sample overlap

Major Findings and Discussion

SBSE with PDMS Twisters achieves up to 1 000× sensitivity over SPME due to larger sorbent volume and efficient stirring. The EG/Silicone Twister expands polarity coverage by capturing hydrogen-bond donors. SA-SBSE further improves recovery for moderately polar compounds by solvent-swelling the Flex Twister phase. mSBSE using multiple Twisters in one vial yields broader analyte coverage and lower detection limits in a single GC/MS run. Twister Back Extraction enables determination of very high-boiling or thermally unstable compounds by combining solvent elution with LC/MS or GC/MS analysis. Conditioning and desorption instruments ensure minimal carry-over and maintain system cleanliness, supporting reproducible ultra-trace analysis.

Benefits and Practical Applications

The Twister® technologies deliver:

• Ultra-high sensitivity and quantitative linearity over wide concentration ranges
• Simultaneous processing of up to dozens of samples for maximum throughput
• Minimal solvent use and labor, reducing cost and environmental impact
• Reusability of sorptive bars (up to 200 cycles), enabling cost-effective field sampling
• Automated integration of extraction, desorption and analysis in a single platform
• Flexible workflows supporting GC/MS, LC/MS and mixed techniques

Future Trends and Potential Applications

Advances may include novel sorbent chemistries for targeted analyte classes, on-bar derivatization strategies, integration with microfluidics for ultra-low volume samples and cloud-based AI-driven method optimization. Applications are set to expand in pharmaceutical QA/QC, biomarker sampling, forensic toxicology and real-time environmental monitoring.

Conclusion

GERSTEL Twister® platforms and associated accessories represent a comprehensive suite of SBSE-based methods that significantly enhance analytical performance for a wide range of sample types. Their combination of sensitivity, automation and versatility makes them indispensable tools for modern analytical laboratories.