Abstract
In a measurement for styrene vapor, the following method is widely used: collection on sorbent tubes, desorption with solvent, and analysis by gas chromatography. In the analysis of low concentration in indoor environment with this method, however, the measurement values have been underestimated because the recovery rate on solvent desorption is low. For this reason the analysis accuracy including the recovery rate needs to be reexamined, and it is essential for that purpose to provide calibration vapor. The continuous generation method using a permeation tube(P-tube) is effective for the preparation of low concentration vapors. In this study, we generated styrene vapor with the P-tube method for preparing calibration vapor in indoor level. The P-tube was made by injecting styrene monomer and stabilizer into polytetrafluoroethylene tubes with a constant diameter. It was kept at a constant temperature to generate vapor and diluted with fresh dry air continuously. The weight of the P-tube was measured at voluntary intervals, and the vapor generated was analyzed qualitatively with gas chromatograph. The results are shown as follows: the weight of the P-tube kept on decreasing at a constant rate for more than a year by adding the stabilizer. A permeation rate was determined by the weight loss of the P-tube per measurement intervals. When a vapor concentration was calculated from the obtained rate and a quantity of dilution gas flow, it became clear that styrene vapor in indoor level was generated from the P-tube. As a result of a qualitative analysis of the vapor, styrene monomer was detected, and dimer and stabilizer were not detected. Therefore, the use of the P-tube made possible stable generation of styrene vapor in indoor level for a prolonged time.
