Field-Based Detection and Monitoring of Uranium in Contaminated Groundwater using Two Immunosensors

Field-based monitoring of environmental contaminants has long been a need for environmental scientists. Described herein are two kinetic exclusion-based immunosensors, a field portable sensor (FPS) and an inline senor, that were deployed at the Integrated Field Research Challenge Site of the U.S. Department of Energy in Rifle, CO. Both sensors utilized a monoclonal antibody that binds to a U(VI)-dicarboxyphenanthroline complex (DCP) in a kinetic exclusion immunoassay format. These sensors were able to monitor changes of uranium in groundwater samples from ∼1 μM to below the regulated drinking water limit of 126 nM (30 ppb). The FPS is a battery-operated sensor platform that can determine the uranium level in a single sample in 5−10 min, if the instrument has been previously calibrated with standards. The average minimum detection level (MDL) in this assay was 0.33 nM (79 ppt), and the MDL in the sample (based on a 1:200−1:400 dilution) was 66−132 nM (15.7−31.4 ppb). The inline sensor, while requiring a grounded power source, has the ability to autonomously analyze multiple samples in a single experiment. The average MDL in this assay was 0.12 nM (29 ppt), and the MDL in the samples (based on 1:200 or 1:400 dilutions) was 24−48 nM (5.7−11.4 ppb). Both sensor platforms showed an acceptable level of agreement (r2 = 0.94 and 0.76, for the inline and FPS, respectively) with conventional methods for uranium quantification.