Determination of Formaldehyde and VOCs in Wood-based Products using an Automated Micro-Scale Chamber

Significance of the topic

The determination of formaldehyde and volatile organic compounds released from wood based products is critical for indoor air quality assessment and health protection. Formaldehyde exposure may cause mucous membrane irritation and is classified as a probable carcinogen. Regulatory limits for short term exposure are often set at 100 µg/m3. Wood adhesives and coatings are major indoor sources of aldehydes and VOCs, demanding reliable emission testing methods.

Objectives and overview of the study

This study presents the development and validation of an automated micro scale chamber method using a GERSTEL DHS Large autosampler. Key aims include simultaneous sampling of formaldehyde and low molecular weight carbonyls via DNPH derivatization and larger VOCs via Tenax TA adsorption, followed by parallel HPLC DAD and thermal desorption GC MS analyses. Method performance and application to different wood based products and toys are demonstrated.

Methodology and instrumentation

The micro scale chamber comprises 1 L inert coated stainless steel vessels with controlled purge gas flow to achieve a surface specific air flow of 0.2778 m3/m2 h and an exchange rate of 3 h-1 at 23 °C and 0% RH. Samples of 6 × 9 cm with dual side exposure were tested. Simultaneous sampling steps:

• Carbonyls: 3 L air pumped through DNPH coated silica gel tubes, eluted with 2 mL acetonitrile, analyzed by HPLC DAD (Nucleoshell RP18, 360 nm).
• VOCs: 0.5 L air sampled on Tenax TA tubes, analyzed by thermal desorption GC MS (Rxi-5ms column, He carrier gas, split 1:5).

Used instrumentation

• GERSTEL DHS Large autosampler with 11 sample positions and PrepAhead capability
• HPLC system with diode array detector
• Thermal desorption unit coupled to GC MS

Main results and discussion

Linearity for aldehyde-DNPH derivatives was excellent (R2 > 0.9991) from 0.01 to 15 µg/mL. Method limits of quantification for formaldehyde, acetaldehyde and acetone were 3.05, 14.8 and 246 µg/m3 respectively. Recoveries for formaldehyde reached 102 % (RSD 6 %), while acrolein recovery was 82 % when full chain calibration was applied. Application to oriented strand board, MDF and plywood revealed formaldehyde emissions of 3, 33 and 147 µg/m3. VOC profiling showed higher aldehydes such as hexanal with Tenax GC MS, whereas DNPH underestimated hexanal due to slow derivatization kinetics. Time dependent emission studies over 72 h demonstrated effective automated monitoring and emission decay modeling.

Benefits and practical applications of the method

• High throughput screening of heterogeneous bulk samples without extensive preparation
• Simultaneous determination of carbonyls and a wide range of VOCs in one automated workflow
• Small chamber size reduces sample and reagent consumption, enabling rapid quality control
• Automated sequential sampling and analysis supports emission kinetics studies and model development

Future trends and potential applications

Further work may integrate automated DNPH cartridge elution and online liquid chromatography. Extending the approach to variable humidity and temperature conditions will allow more realistic indoor simulations. Emission modeling combined with machine learning could predict long term behavior from short term measurements. Applications may expand to coatings, textiles and consumer products.

Conclusion

The automated micro scale chamber method using GERSTEL DHS Large provides an efficient, robust screening tool for simultaneous determination of formaldehyde, carbonyls and VOC emissions from wood based materials. It delivers reliable performance, reduced labor and rapid emission profiling, supporting both quality control and research into emission behavior.

Reference

• Salthammer T, Mentese S, Marutzky R. Formaldehyde in the Indoor Environment. Chem Rev. 2010;110:2536-72.
• ISO 16000-3. Determination of formaldehyde and carbonyls in indoor air. ISO; 2011.
• ASTM D5197-09. Standard Test Method for Determination of Formaldehyde and Other Carbonyls in Air. ASTM International; 2010.
• AgBB Scheme. Health related Evaluation of Emissions of VVOC, VOC and SVOC from Building Products. Umweltbundesamt; 2015.
• ISO 16000-6. Active sampling on Tenax TA sorbents and TD GC MS. ISO; 2010.
• ASTM D6007-14. Standard Test Method for Determining Formaldehyde Concentrations in Air from Wood Products Using a Small Scale Chamber. ASTM; 2014.
• Huang S, Xiong J, Zhang Y. The Impact of Relative Humidity on the Emission Behavior of Formaldehyde in Building Materials. Procedia Eng. 2015;121:59-66.