Intrinsically valid VOC measurements systems : concept to application

• Main Author: Parris, R.
• Published: University of Manchester 2004
• Subjects: 577.14
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.528440

VOCs are generally present in the atmosphere in the gaseous state at concentrations in the 0.1 to 10 I-1g m-3 range. In indoor environments the concentrations tend to be ten times higher. VOCs enter ambient air from industrial fugitive emissions, biogenic sources and most notably from mobile sources associated with motor vehicles. It is known that VOCs in the atmosphere can be transported into soils and ground water by infiltrating precipitation. Development of new and existing analytical tools and sampling techniques to accurately analyse and quantify these compounds in all types of media for environmental management and remediation purposes is critical. This work seeks to incorporate intrinsic valid measurements to a fast field portable soil recovery unit and therefore propose a new advanced methodology for rapid site screening of contaminated land. The production of a new intrinsic validation device using polydimethlysiloxane coupons which contain 0.09 ± 0.011Jg of acetone, 1.02 ± 0.151Jg of toluene-D8 and 10.48 ± 0.721Jg of o-xylene-D10 are described, along with its application to intrinsically valid measurements using active adsorbent sampling, where an active adsorbent method incorporating intrinsic validation protocol is suggested. The development of a new soil screening methodology is next described with the aim of incorporating and transferring the previously described intrinsic validation methodology using the PDMS validation coupons. The initial response of the internal standards when recovered using the soil recovery unit, resulted in encouraging results with RSD between 9 and 34% achieved and a maximum recovered mass of 276.85ng for toluene-D8 and 198.45ng for o-xylene-D10 at 50bars with an extraction time of 1minute. A new method of soil spiking was described, which demonstrated the reproducible toluene soil spiking at the Ug g-1 level. It was found that the recovery of toluene from soil increased with an increase in pressure and extraction time when using the proposed system, with a maximum recovery of 30.8% recorded at 50bars with an extraction time of 2minutes. This trend was also true for the internal standards.