Evaluation of direct reading photoionization detector performance under various operational parameters

Background: A hand-held portable direct-reading monitor, including photoionization detector (PID) is renowned for its good sensitivity, considerable dynamic range, and nondestructive vapor detection ability in comparison to the tardy response of the PID in gas chromatography (GC), which its application has been restricted. In this study, the performance of a PID system (MultiRAE Lite) was evaluated as a replacement of GC in the measurement of toluene in a dynamic adsorption system. Methods: The test was done at different relative humidity levels (۳۰%, ۵۰%, and ۸۰%), temperatures (۲۱, ۳۰, ۴۰°C), and toluene concentrations (۲۰, ۱۰۰, ۲۰۰, and ۴۰۰ ppm). Results: The PID achieved ۴۸% of all measurements meeting the comparison criterion. The results showed that the performance of the PID could be altered by the variables. The best performance of the PID was at temperature of ۲۱°C, the relative humidity of ۵۰%, and concentration of ۲۰۰ ppm with the percentage of readings achieving the criterion of comparison to ۵۸%, ۵۴%, and ۵۲%, respectively. The averages of the PID readings (mean ± SD at ۲۰۰ ppm= ۲۰۷.۹ ± ۸.۷) were higher than the reference method measurements averages (mean ± SD at ۲۰۰ ppm= ۲۰۳.۵ ± ۵.۸). The regression analysis of the toluene results from the PID and the reference method results indicated that the measurements were significantly correlated (r۲ = ۰.۹۳). Conclusion: According to the results, the device response is linear. Therefore, the findings are acceptable in adsorption studies. In this way, the measurement of the sample concentration should be performed using the same instrument before and after the reactor in order to calculate the adsorption efficiency.

کلیدواژه ها:

Toluene ، Temperatures ، Humidity ، Adsorption ، Chromatography ، Gas regression analysis ، Research design