Abstract
A concentration equilibrium sampling-gas chromatography (CES-GC) was studied to measure the content of phenols in atmosphere. After the sample air is drawn through a sampling tube packed with suitable partition material until the concentration equilibrium of the measured components between the gas and liquid phase is reached, the tube is heated and the expelled concentrated components are introduced to GC. Mixed standard gas consisting of phenol, p-cresol and p-ethylphenol in ppb order was prepared using a diffusion cell. As the intra- and interday variations of the concentration of phenols in the standard gas checked by GC were both in the range of 4 to 7% as coefficient of variation, the standard gas was able to be used for the fundamental investigation of the CES-GC. The outline of the procedure was as followed; The standard gas was drawn through the sampling tube, packed with OV-17 stationary phase on Chromosorb G, at 60°C and a flow rate of 100 ml/min for more than 20min. After the sampling process, the tube was heated at 200°C in nitrogen flow (60ml/min), desorbed phenols were transferred to GC. It was found that reproducibilities of peak area ( W) of phenols in the chromatograms obtained by the CES-GC, were 5 to 10% in coefficient of variation. The relationships between W and concentration (C) of standard gas showed linear plots in the range of 0400ppb. The interference of moisture in air on equilibrium was found to be negligible. The method was applied to the determination of phenols in air of pilot plant area; Phenol, p-cresol and p-ethylphenol were 030, 05 and (4585)ppb, respectively. Lower limit of quantitative determination was about 5ppb. This method is easier to handle and more suitable for field practice than other methods such as cryogenic one.
