Determination of Wine Aroma Compounds from Simple Extracts using Automated Large Volume Injection with PTV Solvent Splitting

Importance of the Topic

The volatile composition of wine shapes its sensory attributes and marketability. Accurate profiling of aroma compounds supports quality control, detection of off-flavours and distinction between varietals. Traditional methods often suffer from long sample preparation, high solvent use and limited automation. Advances in large volume injection with solvent venting streamline enrichment of target volatiles while excluding non-volatiles and matrix interferents, improving sensitivity and throughput in routine laboratories.

Objectives and Study Overview

This study aims to develop and evaluate a rapid, automated approach for isolating and quantifying key wine aroma compounds from simple solvent extracts. By employing a solvent venting large volume injection (LVI) technique coupled to a cooled injection system (CIS) and GC-MS, the method minimizes sample handling, reduces solvent consumption and protects the GC-MS from high matrix loads. Performance is demonstrated on extracts from Morio-Muskat and Silvaner wines and validated against established aroma markers.

Methodology and Instrumentation

Sample Preparation

• Ten milliliters of wine spiked with internal standard (2,6-dimethyl-5-hepten-2-ol at 1 mg/L) and 100 µL of 1,1,2-trichlorotrifluoroethane.
• Optionally add 2 g NaCl or 4.2 g (NH4)2SO4 to enhance extraction and reduce emulsions.
• Shake 15 minutes and centrifuge if needed to separate phases.
• Directly use the settled extract for LVI without further clean-up.

Instrumentation

• Gerstel Multi Purpose Sampler in large volume injection mode with 100 µL syringe.
• Gerstel cooled injection system CIS used for solvent venting and analyte trapping.
• Agilent (HP) 5890/5972 GC-MSD with 60 m HP Innowax capillary column (0.25 mm × 0.25 µm).
• Key parameters: 25 µL injection at 20 µL/min, CIS program from 10°C to 250°C, GC oven 40°C to 240°C at 2°C/min, MS scan m/z 25–300.

Results and Discussion

The total ion chromatogram of a Kaltron extract from Morio-Muskat wine revealed over forty aroma compounds free of non-volatile matrix residues such as glycerol or sugars. Major fermentation volatiles (higher alcohols, fatty acid esters, diethyl succinate) and varietal terpenes (linalool, α-terpineol, geraniol, linalool oxides) were baseline resolved. Comparison of Morio-Muskat and Silvaner "fingerprint" profiles highlighted distinct terpenoid patterns, confirming the method’s suitability for varietal differentiation when coupled with chemometric analysis. The solvent venting approach prevented column contamination and maintained MS sensitivity across multiple injections.

Benefits and Practical Applications

• Reduced solvent consumption (100 µL per sample) and minimal sample handling.
• Enhanced sensitivity through large volume injection and solvent removal in-line.
• Automated operation of injection volume, timing and temperature accelerates throughput.
• Preservation of column and inlet integrity by excluding non-volatiles, extending maintenance intervals.
• Applicability in routine QA/QC for fermentation monitoring and grape varietal authentication.

Future Trends and Potential Applications

Anticipated developments include integration with headspace and SPME sampling for broader VOC coverage, expansion to other beverages and food matrices, and coupling with advanced data processing for targeted screening. Further miniaturization of PTV solvent venting interfaces and use of greener extraction solvents may enhance sustainability and adaptability in decentralized laboratories. High-throughput platforms leveraging robotics for sample handling promise to further increase analytical capacity.

Conclusion

Automated large volume injection with PTV solvent venting presents a rapid, solvent-efficient and robust alternative to conventional extraction methods for wine aroma analysis. It achieves sensitive quantification of key fermentation and varietal compounds while safeguarding instrument performance and enabling high sample throughput, making it a valuable tool for wine quality assessment and research.

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