A Combination of Standard (SBSE) and Solvent- Assisted (SA-SBSE) Stir Bar Sorptive Extraction for Comprehensive Analysis of Flavor Compounds in Beverages

Significance of the topic

Comprehensive profiling of flavor compounds in complex aqueous matrices is essential for food quality control, product development and authenticity verification. Standard PDMS-based stir bar sorptive extraction (SBSE) excels at enriching nonpolar analytes but underperforms for polar species. Solvent-assisted SBSE (SA-SBSE) overcomes this limitation by using a solvent-swollen PDMS phase to broaden the polarity range of extracted volatiles and semi-volatiles.

Objectives and overview of the study

This study evaluates a combined SBSE/SA-SBSE workflow to maximize flavor compound coverage in a fruit-and-vegetable smoothie. By performing both extraction modes on aliquots of the same sample and processing data with Aroma Office 2D software, the work aims to demonstrate complementary detection profiles and improve compound identification confidence through both mass spectrometric and linear retention index matching.

Methodology and instrumentation

Sample: A centrifuged smoothie blend of apple, grape, lemon, strawberry, raspberry, carrot and beet. Five milliliters of supernatant were adjusted with 30 % NaCl and aliquoted into 10 mL vials. Extractions: Standard SBSE employed a 24 µL PDMS Twister, while SA-SBSE used a 63 µL solvent-swollen FLEX-Twister (swollen with 105 µL DCM/diisopropyl ether 1:1). Both modes ran at 25 °C, stirring 800 rpm for 60 min. Desorption: Each stir bar underwent liquid back-extraction in 0.5 mL acetone (30 min, 800 rpm), followed by large-volume injection (200 µL) into a thermal desorption unit.

Instrumentation

• Thermal desorption unit (TDU) with MPS autosampler and PTV inlet on an Agilent 7890A GC.
• Agilent 5975C single quadrupole mass selective detector operating in scan and SIM modes.
• DB-Wax Ultra Inert capillary column (20 m × 0.18 mm × 0.30 µm).
• Aroma Office 2D software for automated MS/RI matching.

Main results and discussion

Comparison of total ion chromatograms revealed 52 compounds commonly detected by both SBSE modes, including esters, alcohols, terpenes, acids, aldehydes, phenolics and lactones (log Kow 1.05–7.10). SA-SBSE uniquely identified 16 additional polar analytes (short-chain fatty acids, diols, furans, sulfur compounds, phenols) while conventional SBSE alone recovered 14 more apolar species (ketones, lactones, phenolics). Co-elution of polar SA-SBSE peaks occasionally masked certain analytes (e.g., ethyl-3-methylthiopropanoate, p-anisaldehyde), requiring manual spectral verification.

Benefits and practical applications

This dual-extraction strategy extends the analyte polarity window achievable in a single workflow, enabling more exhaustive flavor profiling of beverages and other food products. It supports regulatory compliance, sensory optimization, authenticity testing and troubleshooting of off-flavors in quality assurance laboratories.

Future trends and potential applications

Advances may include integration with two-dimensional GC or high-resolution MS to further resolve co-elutions, automation of solvent-swelling steps, and expansion of RI databases for emerging flavor compounds. The combined SBSE/SA-SBSE approach can be adapted to environmental or clinical matrices where exhaustive volatile profiling is required.

Conclusion

Deploying both standard and solvent-assisted SBSE with combined MS and RI matching substantially increases the range of detectable flavor compounds in complex beverages. The complementary extraction modes yield enhanced sensitivity for polar and apolar analytes, improving confidence in comprehensive flavor analysis.

References

• Baltussen E, Sandra P. Stir Bar Sorptive Extraction (SBSE): Theory and Principles. J Microcol Sep. 1999;11:737–747.
• David F, Sandra P. Stir bar sorptive extraction for trace analysis. J Chromatogr A. 2007;1152:54–69.
• Ochiai N, Sasamoto K, Sandra P. Solvent-assisted SBSE for enhanced recovery of polar solutes. J Chromatogr A. 2016;1455:45–56.