IMMUNOCHEMICAL SCREENING FOR PETROLEUM HYDROCARBONS IN SOIL Reliability and Suitability of Commercially Available Test Kits

摘要

Mineral oil hydrocarbons belong to the most frequently found contaminants in soil samples, e.g., on former military sites. Because of their ecotoxicity and the hazard for ground water a remediation of contaminated sites is necessary. During the investigation concerning the extent of pollution and for the supervision of sanitation measures a field screening method, which gives information about the degree of contamination within a short period of time, would be advantageous. It could help to save time and thereby reduce costs, because decisions about further action could be met without delay. In Germany various immunoassay test kits for petroleum hydrocarbons, which can be used for on site analysis, are commercially available. These test kits do not detect the whole spectrum of mineral oil hydrocarbons, but they are suitable for the analysis of gasoline, diesel and jet fuels, as well as heating oil in soil samples. The reliability and suitability of three test kits have been investigated in the field on several fuel contaminated sites. Therefore 86 soil samples of different origin, involving a variation of matrix composition, age of contamination and spectrum of hydrocarbons, were split on site into two subsamples. One part of the sample was analysed with the immunoassay test kits, if possible directly on site. The second subsample was sent to a laboratory for the determination of the mineral oil hydrocarbon content with IR spectrometry, the commonly used reference method for this parameter. For evaluation both results were compared with each other. If the test kit result lay within the tolerance range of the IR result, it was assessed to be correct. In the case of a discrepancy between immunoassay and IR result, the analysis of the test kit extract by gas chromatography could give information about the reason for this, e.g., inhomogeneity of the sample. Moreover, the gas chromatogram could help to explain incorrect results, as it shows whether there was an atypical spectrum of petrol hydrocarbons in the soil sample concerned, or whether interfering substances were present.