Material emission tests save automotive producers and suppliers significant amounts of time and cost. Emission tests for Volatile Organic Compounds (VOCs) and Semi-Volatile Organic Compounds (SVOCs) can predict the usefulness of materials long before they are incorporated into components or into the finished vehicle.
A material level test method (VDA 278) was published by the German Association of Automobile Producers (VDA). The method was developed by Daimler AG, producers of Mercedes cars, in cooperation with GERSTEL based on the Thermal Desorption System (TDS). The method is widely used.
A small sample of material is placed directly into a thermal desorption tube. Examples are dashboard material, carpet fibers, and door seal rubber. An autosampler inserts the tube into a Thermal Desorber, such as the GERSTEL TDS 3 or TD 3.5+, in which the sample is heated in a flow of inert carrier gas. A 90 °C extraction is first used to determine the VOC value. A subsequent 120 °C extraction is used to determine the FOG value for condensable substances (SVOCs).
Thermally extracted compounds are transferred to a smaller focusing trap for introduction to a GC column. The compounds are separated, and then identified and quantitated using a mass spectrometry detector (MSD). The VDA 278 method is a Total VOC (TVOC) method. Compounds are semi-quantitatively determined using toluene as internal standard. The instrument used must be non-selective with good recovery of a broad range of challenging compounds, including alkanes, amines and sulfur-organic compounds. That is exactly what the GERSTEL Cold Injection System CIS 4 provides: Non-selective cryogenic focusing using Liquid Nitrogen (LN2) cooling, eliminating the need for a sorbent and the associated analyte loss. The VDA method notes that a sorbent-trap based apparatus type has been shown in practice to yield lower values for very low volatility substances.
Accurate temperature control is critically important for the accuracy of thermal extraction. GERSTEL provides a temperature verification and calibration kit. Temperature validation can be performed by the user or by Gerstel Service.
GERSTEL understands and support the VDA 278 method better than anyone else. We also have significant involvement with ISO, DIN, SAE, and other standardization bodies; our experts provide application advice in order to meet even challenging material emissions problems.