On-site immunoanalysis of nitrate and nitroaromatic compounds in groundwater

A miniaturized field-portable immunosensor (FAST 2000) was field tested at former military munitions sites for the detection and quantitation of TNT a nd RDX in groundwater. Developed by the Naval Research Laboratory (NRL) and engineered by Research International, Inc. (Woodinville, WA), the immunose nsor performed on-site analysis of contaminated groundwater at three milita ry bases identified by the U.S. Environmental Protection Agency (EPA) as pr iority Superfund cleanup sites. The locations were Naval Submarine Base, SU BASE Banger, Banger, WA; Umatilla Army Depot Activity, Umatilla, OR; and Na val Surface Weapons Center, Crane, IN. The immunosensor uses an antibody as the recognition element for the explosive molecule in a displacement assay format. Detection of the explosive molecule contained in groundwater is co nfirmed by an increase in fluorescence over background from the displaced c yanine-labeled explosive analogue. At each site, groundwater samples contai ning unknown concentrations of explosives were collected from monitoring we lls and analyzed on-site by the portable immunosensor with no sample pretre atment or concentration. Groundwater samples were split and shipped to an i ndependent certified U.S. EPA laboratory for analysis using SW-846 Method 8 330 (HPLC). Statistical analysis based on linear regression curves comparin g the immunosensor and the HPLC method showed good correlation, although si te-dependent problems were encountered with some samples. The immunosensor required small sample volumes (150 muL/test) and less than 3 min to analyze samples with a method detection limit of 10 mug/L in the laboratory-spiked samples. The results from this field demonstration show the viability of t he immunosensor for on-site analysis of explosives to assist in environment al remediation and monitoring efforts.