Markes Micro-Chamber/Thermal Extractor (μ-CTE)

Importance of the Topic

Rapid and reliable screening of volatile organic compounds (VOCs) and semi-volatile organic compounds (SVOCs) emitted from materials plays a critical role in product quality control, regulatory compliance and indoor air safety. Modern regulations (REACH, ISO 12219-3, ISO 16000-25, CARB, IgCC) demand both certification testing and in-house monitoring of emissions from construction products, consumer goods and vehicle interiors. Traditional chamber methods require days to weeks of sampling, while micro-scale chambers enable high-throughput screening within minutes to hours directly at the production line.

Study Objectives and Overview

This brochure introduces the Markes Micro-Chamber/Thermal Extractor (µ-CTE™) technology for fast emissions screening. It outlines:

• The design and operating principles of the µ-CTE units (four- and six-chamber versions, ambient to 250 °C).
• Comparative performance data against standard small-scale emission chambers.
• Applications across construction materials, car trim, textiles, foods, tobacco and consumer goods.
• Method compatibility with TD-GC/MS, HPLC and real-time detectors.

Methodology and Instrumentation

The µ-CTE comprises modular stainless-steel micro-chambers (44 mL or 114 mL each, inert coated). Samples (bulk or planar) are placed in sample pots or fixed under a collar defining the exposed surface area. A constant flow of purified air or inert gas is swept across the sample at controlled temperature and flow (50–350 mL/min). Organic vapours exit each chamber and are captured on:

• Standard sorbent tubes (e.g. Tenax®) for VOC/SVOC collection.
• DNPH cartridges for formaldehyde sampling.

No external pumps or mass flow controllers are required due to patented flow control technology (UK patent application 0501928.6). After an equilibration period (20–30 min), vapour sampling is initiated for 15–120 min depending on target analytes and regulatory standards. Collected samples are analysed offline by:

• Thermal desorption–gas chromatography–mass spectrometry (TD-GC/MS) per ISO 16000-6, ISO/EN 16017, ASTM D6196.
• Liquid chromatography (HPLC) for DNPH derivatized formaldehyde.
• Optional near-real-time MS or electronic nose detectors.

Main Results and Discussion

Independent studies confirm strong correlation between µ-CTE data and conventional 1 m³ chambers at 3 days exposure, for both VOCs and SVOCs (Schripp et al. Anal. Bioanal. Chem. 2007; PARD Report, University of Warwick). Key findings include:

• Low blank levels (<1 ng individual VOCs; TVOC <30 ng at 120 °C; <12 ng at 200 °C).
• Flow stability across a wide range of sorbent tubes and backpressures.
• High precision (RSD <10 %) for styrene and 1,3-butadiene in ABS terpolymer testing.
• Effective recovery of semi-volatile compounds under elevated temperature and flow conditions.
• Versatility to perform surface, bulk and permeation testing with appropriate accessories.

Benefits and Practical Applications

The µ-CTE offers multiple advantages for industrial and laboratory workflows:

• High throughput: four to six samples per hour for VOC screening; four to six samples per 2–4 h for formaldehyde.
• On-site QC: fast feedback near production lines reduces trial times and material waste.
• Cost-effectiveness: minimal gas consumption with toggle-valve control; no expensive flow controllers or dedicated pumps.
• Broad applicability: construction materials (plasterboard, flooring, adhesives), car trim, electronics, textiles, food aroma profiling, consumer goods (toys, solvents).
• Regulatory alignment: supports emerging ISO, ASTM and VDI draft standards for micro-scale chambers.

Future Trends and Potential Uses

Continued method development and standardization of micro-chamber protocols will drive wider adoption. Future directions include:

• Integration with inline, real-time detection (TD-MS, PTR-MS) for continuous monitoring.
• Automation and robotics for unattended sampling and analysis.
• Extended temperature range and humidity control for simulating extreme environments.
• Expansion into volatile profiling for biological and agri-food research (aroma fingerprinting, spoilage indicators).
• Application in barrier testing for personal protective equipment and packaging materials.

Conclusion

The Markes µ-CTE platform delivers a robust, rapid and sensitive approach to emissions screening, bridging the gap between long-term certification chambers and real-time monitoring needs. It enables manufacturers and test laboratories to perform meaningful VOC, SVOC and formaldehyde assessments within minutes to hours, providing critical data for quality control, product development and regulatory compliance.

Reference

1. Schripp T., Nachtwey B., Toelke J., Salthammer T., Uhde E., Wensing M., Bahadir M. A microscale device for measuring emissions from materials for indoor use. Anal. Bioanal. Chem. 2007, 387, 1907-1919.
2. PARD Report: Correlation between the VDA 276 test and micro-chamber testing. WMG, University of Warwick, UK.
3. Screening VOC emissions from textile floor coverings (GUT carpet label).
4. VDI 2083-17 (proposed ISO) Clean room technology – Compatibility with required clean lines class and surface clean lines.
5. ASTM Draft standard practice for micro-scale test chambers for rapid assessment of vapor-phase organic compounds emitted by materials.
6. ISO WD 12219-3 Draft standard for screening car trim component emissions using micro-chambers.