Sub-surface probe module equipped with the Karlsruhe Micronose KAMINA using a hierarchical LDA for the recognition of volatile soil pollutants

For the integration in an electric hammer driven soil air probe a battery-operated cylindrical EN module was developed on the basis of the Karlsruhe Micronose KAMINA for rapid depth-resolved soil screening. The EN module contains the complete battery-operated electronics and a 3.5 mm × 3 mm KAMINA gradient microarray chip with a single Pt-doped SnO2-film. In order to achieve high mechanical stability and low power consumption the microarray chip is fixed only with bond wires within the clearance of a ceramic carrier card. Test exposures of the module were carried out with a variety of potential soil pollutants (such as chlorinated, aromatic, aliphatic hydrocarbons in air with 80% r.h.) in order to investigate the KAMINA's gas analytical performance. The detection limits were <1 mg/m3 for aromatic and aliphatic hydrocarbons, except 10–500 mg/m3 for chlorinated hydrocarbons at response times <100 s. The gas discrimination power was found appropriate to distinguish between these type of pollutants. A novel hierarchical linear discriminant analysis has been developed for online classification of volatile soil pollution.