A PAL RTC autosampler equipped with the new V-ITEX module for automated headspace extraction, set against a starry background symbolizing innovation.

5 min 11.03.2025

Beyond Headspace: Introducing Vacuum In-Tube Extraction (V-ITEX)

A collaboration between Agroscope, GERSTEL, and PAL System has led to an advancement in headspace extraction technology. By replacing the discrete pump strokes of traditional In-Tube Extraction (ITEX) with a continuous, controlled vacuum, the new Vacuum In-Tube Extraction (V-ITEX) technique allows for a more exhaustive and gentle extraction of volatile and semi-volatile compounds. This refinement enables analysis at lower temperatures, preserving thermally sensitive analytes and expanding the range of compounds that can be studied. Read on to explore the technical principles behind V-ITEX and review its application in recent scientific studies, from non-invasive breath analysis to the quality control of food products.

Hagen Gegner

Scientific Communications Specialist

Visit Bio

Advancing the Analysis of Volatile and Semi-Volatile Compounds

The analysis of volatile organic compounds (VOCs) is essential across a wide range of scientific disciplines, from food science and environmental monitoring to clinical diagnostics. A recent collaboration between the Swiss agricultural research institute Agroscope, GERSTEL, and PAL System has resulted in the development of Vacuum In-Tube Extraction (V-ITEX), an automated sample preparation technique for gas chromatography/mass spectrometry (GC/MS).

This technology refines the established method of In-Tube Extraction (ITEX) by incorporating a continuous vacuum, which permits extraction at lower temperatures. This article provides a technical overview of the V-ITEX principle and reviews its application in recent scientific literature.

Diagram comparing traditional ITEX using discrete strokes for enrichment with the new V-ITEX method, which uses a continuous vacuum to pull headspace through the trap, improving extraction.

The V-ITEX Principle of Extraction: From Plunger Strokes to Continuous Vacuum Flow

Traditional dynamic headspace (DHS) techniques, such as In-Tube Extraction (ITEX), are used for the solventless extraction and enrichment of volatile compounds from a sample's headspace. In a classical ITEX setup, a gastight syringe is used to perform repeated pump strokes, actively drawing the headspace gas through a tube containing an adsorbent material. While effective, this process is discontinuous. The central modification in the V-ITEX technique is the replacement of these discrete syringe strokes with a continuous and controlled vacuum. This was born out of a need at Agroscope for a more dynamic and exhaustive extraction method for analyzing complex and thermally labile samples, such as cheese and biological fluids. Inspired by techniques like Solvent-Assisted Flavour Evaporation (SAFE), which uses a vacuum to distill volatile compounds at low temperatures, the concept of applying a continuous vacuum to the ITEX process was developed and prototyped [1]. In the automated V-ITEX system, a vacuum pump is integrated into the PAL System autosampler setup. It continuously pulls the sample headspace through the sorbent-filled ITEX trap at a controlled low pressure. This dynamic flow allows for a more exhaustive extraction process compared to the stepwise equilibrium of traditional ITEX.

I want to know more See the publication

Key Technical Advantages

This modification of the extraction process provides several distinct technical benefits:

Increased Extraction Efficiency and Sensitivity: The application of a continuous vacuum allows for a more exhaustive, dynamic extraction process that improves the extraction rate and capacity. In comparative studies, the resulting signal intensity for target compounds was up to 450 times higher than that achieved with traditional HS-SPME and HS-ITEX under the same experimental conditions, enabling lower limits of detection [1, 7].
Gentle Extraction of Thermally Labile Compounds: Operating under reduced pressure enables the efficient extraction of volatile compounds at lower temperatures. This gentle approach minimizes the risk of thermal degradation and artifact formation, a critical advantage when analyzing sensitive analytes in complex biological or food matrices [1, 3].
Broader Analyte Coverage: The dynamic and exhaustive nature of the extraction expands the analytical window to a wider range of compounds. V-ITEX has demonstrated the effective capture of diverse chemical classes, including both highly volatile and semi-volatile compounds, which are often challenging to analyze with conventional headspace techniques [4, 5, 6].

A graphic illustrating the benefits of V-ITEX, including low-temperature extraction for labile compounds and exhaustive extraction for lower detection limits, built on the reliable PAL System platform.

Scientific Applications and Validation of V-ITEX

The performance of this vacuum-assisted approach was first detailed by Fuchsmann et al. in a 2019 publication in the Journal of Chromatography A. This foundational study compared the new technique, termed Dynamic Headspace Vacuum Transfer In-Trap Extraction (DHS-VTT), against traditional headspace solid phase microextraction (HS-SPME) and headspace in-tube extraction (HS-ITEX).

The results demonstrated a significant improvement in extraction efficiency, showing that the signal intensity for target compounds could be up to 450 times higher with DHS-VTT. This enhancement allows for the analysis of smaller sample quantities and a more effective, exhaustive extraction of a broad range of volatile compounds [1]. Building on this foundational work, the technology has since been applied in a variety of scientific fields.

Melted Raclette cheese in traditional pans. V-ITEX technology was used to analyze the volatile compounds responsible for off-flavors in this type of cheese.

Food Science & Flavor Analysis

V-ITEX provides a sensitive method for identifying key aroma and off-flavor compounds in complex food matrices like cheese.

The initial impetus for V-ITEX development came from the challenges of aroma analysis in complex food matrices. In a 2021 study, Meng et al. used DHS-VTT coupled with GC/MS and olfactometry to investigate the formation of compounds responsible for a "malty" off-flavor in Swiss Raclette-type cheese. The method's sensitivity and gentle extraction conditions were crucial for identifying and quantifying key volatile compounds like 3-methylbutanal and its derivatives, providing insights into their formation pathways during cheese fermentation [3].

A vial of blood serum lying on a laboratory test request form. V-ITEX is used to analyze the serum volatilome to find biomarkers related to diet and health.

Nutritional Science & Metabolomics

This technique helps link dietary intake to the human metabolome by analyzing volatile biomarkers in serum after food consumption.

The V-ITEX workflow has been extended into the field of "nutrivolatilomics," which seeks to connect food consumption to the human metabolome. Meng et al. (2023) analyzed the serum volatilome of young and older men after milk and yogurt consumption using DHS-VTT-GC-MS. The study successfully identified age-dependent metabolites and potential dietary biomarkers, such as p-cresol and 3,5-dimethyloctan-2-one, demonstrating the method's utility in nutritional research [4].

An artistic representation of lungs made from flowers and branches. V-ITEX technology aids in the sensitive detection of volatile organic compounds in exhaled breath for health monitoring.

Clinical & Animal Health Diagnostics ("Exhalomics")

V-ITEX enables non-invasive health monitoring by detecting trace-level volatile organic compounds in exhaled breath from both humans and animals.

The analysis of VOCs in exhaled breath is a promising non-invasive diagnostic tool, but it is challenged by the low concentration of analytes. Wüthrich et al. (2024) reported the first use of DHS-V-ITEX-GC-MS for the analysis of exhaled breath condensate (EBC) as a complementary method to enhance feature identification in real-time breath analysis [5]. Similarly, Eichinger et al. (2024) applied the technique to analyze VOCs from the exhaled breath of dairy cows, establishing V-ITEX as a suitable technique for untargeted screening of the animal volatilome for health and metabolic monitoring [6].

A close-up of a honeycomb structure showing beeswax and pollen. V-ITEX provides a rapid and solvent-free method for quantifying contaminants in beeswax.

Environmental & Residue Analysis

V-ITEX offers a rapid, automated, and solvent-free method for quantifying contaminants and residues in complex environmental samples like beeswax.

Ensuring the safety and quality of products like beeswax requires sensitive methods to detect potential contaminants. Kast et al. (2022) developed and validated a DHS-VTT-GC-MS method for the rapid quantification of 1,4-dichlorobenzene (PDCB) and thymol residues in beeswax. The method proved significantly faster than previous solvent-based extraction techniques, and the study concluded that its automated, solvent-free, and reproducible nature makes it highly suitable for routine quality control of volatile contaminants [7].

Conclusion

The development of Vacuum In-Tube Extraction (V-ITEX) represents a significant refinement of dynamic headspace sampling. By integrating a continuous vacuum into the proven ITEX framework, the technique provides a gentle, sensitive, and automated solution for the analysis of volatile and semi-volatile compounds. The successful application of this method across diverse scientific fields - from identifying subtle flavor compounds in cheese to detecting trace-level biomarkers in breath - demonstrates its versatility and robustness.

We thank our research partners at Agroscope for their foundational scientific work and collaboration in bringing this technology from a laboratory prototype to a commercially available solution.

The automated V-ITEX technology is available through our partner, GERSTEL, as a fully integrated option for the GERSTEL MultiPurpose Sampler (MPS robotic).

I want to try it! Download Flyer

References

[1] Fuchsmann, P., et al. (2019). "Development and performance evaluation of a novel dynamic headspace vacuum transfer 'In Trap' extraction method for volatile compounds and comparison with headspace solid-phase microextraction and headspace in-tube extraction." Journal of Chromatography A, 1601, 60-70.

[2] GERSTEL (2024). Vacuum-In-Tube-Extraction (V-ITEX). Product Information.

[3] Meng, H. Y., et al. (2021). "Formation of 3-Methylbutanal and 3-Methylbutan-1-ol Recognized as Malty during Fermentation in Swiss Raclette-Type Cheese, Reconstituted Milk, and de Man, Rogosa, and Sharpe Broth." Journal of Agricultural and Food Chemistry, 69(2), 717–729.

[4] Meng, H. Y., et al. (2023). "Age-Dependent Serum Volatilomics of Milk and Yogurt Intake: A Randomized Crossover Study in Healthy Young and Older Men." Journal of Proteome Research, 22(4), 1201–1212.

[5] Wüthrich, C., et al. (2024). "Comparative analysis of feature annotation methods for SESI-HRMS in exhaled breath analysis." Journal of Chromatography A, 1734, 465296.

[6] Eichinger, J., et al. (2024). "Optimization of volatile organic compounds sampling from dairy cow exhaled breath using polymer-based solid-phase extraction cartridges for gas chromatographic analysis." Journal of Breath Research, 18(3), 036001.

[7] Kast, C., et al. (2022). "Quantitation of 1,4-Dichlorobenzene and Thymol in Beeswax Using Dynamic Headspace Vacuum Transfer in Trap Extraction Prior to Gas Chromatography-Mass Spectrometry." Molecules, 27(17), 5367.