Preparation Of VOCs Absorption Tube Certified Reference Materials

More attention has been paying to the indoor air monitoring as for heavily increasing indoor air pollution nowadays. Correct and comparable determination size of the volatile organic compounds in the room is always the emphasis and difficulty during the related research work. Absorption tubes, which are packed with active carbon and Tenax-TA, used to sample the volatile organic compounds in ambient air, are widely accepted for its simple method, high repeatability and stability. The procedure, that the standard absorption tubes prepared by the gas standard materials, approaches the actual sampling process and gradually accepted for the international society. The comprehensive various countries' research experience indicated that, applied the low-density gas standard materials prepared by dynamic volumetric method and the standard adsorption tubes to monitor the air quality inside and outside the room could satisfy the measurement standard. This is important to unifies our country VOCs measurement result and the survey size may trace to the source.In this paper we reported a convenient method, which is based on ISO 6145, to prepare the standard absorb tubes with VOCs components (involved n-hexane, benzene, toluene, ethylbenzene, o-xylene, p-xylene, m-xylene, styrene, butyl acetate, hendecane). The standard VOCs mixture gasses are generated by a dynamic volumetric diffusion or permeation method and a mass flow control pump complement system. Thermal desorption (TD) combined gas chromatography (GC) and mass spectrometry detection (MS) are used to analyze the standard absorb tubes. Experiments indicated that the prepared standard absorb tubes had good repeatability,linearity and stability. Under seal condition the change of the standard adsorption tubes is not bigger than 2% (RSD) in a year. And we applied the standard absorb tubes on comparison of determination of VOCs in the vehicles. The comparison was organized by Standard Regimentation Organization and National Institute of Metrology, the result indicated that, the application effect was good and the standard adsorption tubes could satisfy the requirements of determination reference materials in the labs. The above research work, passed the expert appraisement, and was allowed to declare the country reference material.