Measurement of individual compounds with detection
limits up to ppb level in soil and groundwater
EnISSA Membrane Interface probe
Accurate soil investigations and their sampling programs are a critical component of reliable, efficient and cost-effective cleanup processes.
Traditional sampling methods are characterized by low detection levels and a broad analysis spectrum. However delineation of the contaminated area by traditional sampling methods is not only a time and cost consuming task but also parts of the contaminated area could be overlooked.
“On site” soil characterization technologies such as the MIP and ROST techniques are already frequently applied to obtain additional information which cannot be obtained by traditional sampling methods. Although conventional MIP has proven its use in source zones survey, the characterization of plumes is difficult due to the rather high detection limits of the conventional detectors (PID, ECD, FID). Detection limits are highly dependent on membrane temperature, detector maintenance, operator experience, ... (Bodem 3, 2008). A recent article (J. Soil Sediments 9:74-82 (2009)) mentions detection limits of 3000-10000 ug/l. Due to modifications of the detectors which cause less background noise, some providers can detect concentrations in optimal conditions down to ca. 200 - 500 ug/l, but which is still much higher compared to soil clean up values.
The EnISSA MIP system uses the standard MIP configuration combined with the improved detection capabilities of a fast GC/MS method. The advantages of using a GCMS as detector, are the low intrinsic detection limit of the detector and the capabilities to measure individual compounds, hence bringing the lab into the field. Within the EnISSA technology, the GCMS system has been modified in order to allow very short analysis times. By using a combination of an innovative GCMS configuration and a smart method optimisation, it was possible to develop analysis methods with a very short cycle time (typically 1 min).These short cycle times are crucial for the practical implementation of a MIP-GCMS in the field and enable the advantages of GCMS detection for the full profile. Field evaluations demonstrated that the EnISSA MIP is capable of measuring soil profiles for individual compounds with detection limits near 10-20 µg/l.
The MIP equipment and detectors are installed in a van with its own power generator but can also be converted to a manually transportable configuration for measurements at difficult locations (inside buildings etc.).