In situ GC-MS measurements

Soil contaminants with volatile components can cause inconvenience and health risks during excavation work or affect the indoor air quality of neighbouring homes due to vapour intrusion. Particularly in densely populated areas, attention for these problems is increasing, and close monitoring of such dispersion is important.

The classic techniques, like adsorption tubes and PIDs both have limitations. For example, adsorption tubes take a long time to analyse, making it impossible to respond resolutely and immediately. On the other hand, the technology with the PIDs only measures a sum parameter, making it impossible to test against individual exposure standards. The same applies when this technology is used to monitor industrial gas flows.

In 2009, Witteveen+Bos, previously MAVA, started working on the development of EnISSA. This product focuses on performing high-resolution and real-time soil investigation, 'to collect more data as part of source as well as plume analysis to be able to reduce the spatial and analytical uncertainty in soil analysis'. To do this, EnISSA uses a mobile GC-MS system.

Based on the EnISSA technology, we also developed ISAIRA (In situ air analysis). This is a method for performing in situ and real-time gas analyses. This concerns soil air, indoor air, ambient air and industrial gas flows.

ISAIRA makes it possible to:

• Monitor concentrations of volatile substances in ambient air at various points and thus indicate in a timely manner when the exposure standard for a component is being exceeded.
• Monitor variations in industrial emissions over a longer period to reveal fluctuations resulting from changing process parameters, for example.
• Perform a rapid screening of the quality of the indoor air and track any vapour intrusion routes.