Assessment of air passive sampling uptakes for volatile organic compounds using VERAM devices

A calibration chamber has been designed and employed for the simple and easy determination of uptake sampling rate (R_S) of volatile organic compounds (VOCs) from air using passive samplers. A flow of clean air was continuously spiked, at a constant VOC concentration, by the microinjection of a standard solution by means of a T-type tube. The developed system allowed the complete evaporation at room temperature of the standard solution in acetone and the air concentration of VOCs was easily controlled by the regulation of the clean air flow, the standard solution concentration and its flow. Active sampling was employed for monitoring the true concentration of the evaluated compounds inside the calibration chamber, using Tenax-filled desorption tubes and a low flow personal air sampling pump. Versatile, easy and rapid atmospheric monitor (VERAM) devices were employed for the passive sampling of benzene, toluene, ethylbenzene, xylenes, α-pinene, camphene, myrcene, p-cymene, and limonene from air. The R_S values obtained for the passive sampling of VOCs, using the developed calibration chamber, were in the range of 1.3-16.0m³day^-1 in accordance to previous calibration studies performed for VERAM samplers. The developed calibration chamber provided a continuous flow with a constant concentration of the evaluated compounds that allowed the simultaneous deployment of several samplers for a rapid establishment of R_S for a passive sampler type and the easy comparison between different devices.