Office Chair TVOC

The detection of TVOC in office chairs focuses on controlling the emission amount, achieving precise analysis through climate chamber sampling combined with GC-MS quantitative determination. TVOC (Total Volatile Organic Compounds) is a collection of organic compounds with boiling points between 50°C and 260°C that are volatile at room temperature. Its detection needs to cover modules such as principles, pollution sources, sampling methods, analytical techniques, and environmental grade determination.

Emission Mechanism and Pollution Sources of TVOC
The emission of TVOC from office chairs primarily stems from raw materials and processing techniques:

1. Polyurethane Foam: Residual by-products from the reaction between polyols and isocyanates slowly escape, forming a long-term emission source.
2. Fabric Treatment: Finishing agents and coating solvents (such as DMF and toluene) introduced during the finishing processes of fabrics or leather continue to desorb, with significant emissions especially in the initial stages.
3. Metal and Plastic Components: Plasticizers and additives in powder coatings, as well as additives in plastic armrests/star bases (such as phthalates), may volatilize.
4. Adhesives: Solvents (such as ethyl acetate) and monomers (such as formaldehyde) that are not fully cured during the bonding process have a long release cycle and are key pollution sources.
   The emission rate is influenced by environmental factors: an increase in temperature accelerates molecular diffusion and surface desorption; changes in humidity may alter the formation pathways of hydrolytic compounds; and the air exchange rate directly affects the cumulative concentration of pollutants within the chamber.

Climate Chamber Sampling and Sample Preparation
Before detection, samples need to be pre-treated: after removing external wrapping materials, they are placed in a clean environment to equilibrate and eliminate transportation contamination. During testing, the entire chair is placed in a climate chamber with constant temperature and humidity, and temperature, humidity, air exchange rate, and load rate are set to ensure that the background concentration in the chamber is below the limit. After exposure for a specified time, a sampling tube filled with an adsorbent is connected to the outlet air path to collect chamber air at a constant flow rate, which is then sealed and analyzed promptly.

GC-MS Quantitative Determination Technique
Thermal desorption injection is preferred for the sampling tube, or carbon disulfide solvent desorption can also be used. The gas chromatograph is equipped with a weakly polar or moderately polar capillary column to separate components with widely differing boiling points through programmed temperature increase; the mass spectrometer detector collects mass spectra in electron ionization (EI) scanning mode, combining library searches with standard substance retention times for qualitative confirmation of common components such as toluene, xylene, and ethylbenzene. Quantification is performed using the external standard method or internal standard method, calculating the mass of each component through the characteristic ion peak area, and finally summing to obtain the TVOC emission amount (unit: mg/m³).
This technique can accurately identify pollution sources and provide a scientific basis for determining the environmental grade of office chairs.