Use of solid extraction chromatography for determination of uranium in seawater and brine

Bench scale field trials were initiated for the development of effective technology for recovery of uranium from seawater using acrylonitrile absorbents synthesized by radiation grafting. One of the important needs is to ensure quality assurance for the accurate measurement of heavy metal ion concentrations from lean solutions such as seawater and brine. Efforts have been made at Bioassay Laboratory of Radiation Safety Systems Division in India to improve the radiochemical separation and detection techniques for rapid, sensitive and accurate estimation of uranium in seawater samples. The earlier method using ion exchange had disadvantages of being lengthy and required use of sulphuric acid. Hence, a method was developed for estimation of uranium concentration in natural seawater and brine (desalination plant effluents) samples by solid extraction chromatography (SEC) using UTEVA resin (Uranium and TEtraValents Actinides). This resin consists of dipentyl pentylphosphonate sorbed onto an inert polymeric support. Using SEC technique, the complete analysis results are available within a day and as the resin is very specific for uranium extraction from the samples, it is easier to eliminate interfering transition ions like vanadium and iron from the samples. This paper reports the standardization of radiochemical procedure for uranium from seawater and brine samples and its determination by alpha spectrometry.