This Small Business Innovation Research Phase I project proposes a novel radiochemical sensor that combines extraction chromatography with an aqueous flow-cell radiation sensor. The sensor will allow for quantification of a radioactive isotope or group of radioactive isotopes in surface water, groundwater and drinking water at much lower levels for alpha- and/or beta-emitting radionuclides. This increased sensitivity over conventional on-line sensors will greatly enhance the tools used by scientists and engineers for environmental monitoring Monitoring of radioactivity is important in environmental science applications. Traditional radiochemical techniques are time consuming and expensive. The sensor offers the possibility of near real-time quantification of radioactive contamination at a lower cost and higher sensitivity than currently available techniques. Monitoring of radioactive effluent from hospitals, research institutes and/or production facilities is just one potential application.