Rapid and simultaneous determination of Strontium-89 and Strontium-90 in seawater

A rapid method has been developed for the direct determination of radiostrontium (89Sr and 90Sr) released in seawater in the early phase of an accident. The method employs a fast and effective pre-concentration of radiostrontium by Sr-Ca co-precipitation followed by separation of radiostrontium using extraction chromatography technique. Radiostrontium is effectively separated in the presence of excessive dominant salts of seawater. Čerenkov and liquid scintillation assay (LSA) techniques are used to determine 89Sr and 90Sr. Sample preparation time is approximately 4 h for a set of 10 samples. The method was validated using spiked seawater samples at various activity ratios of 89Sr:90Sr ranging from 1:10 to 9:1. The mean chemical recovery of Sr was 85 ± 3%. 90Sr showed variable relative bias which enhanced with increasing ratio of 89Sr:90Sr and was in the range ±21%. The highest biases of 90Sr determination were due to lower activity concentrations of 90Sr and are regarded as acceptable in emergency situations with elevated levels of radiostrontium in the sample. The minimum detectable concentration (MDC) of 90Sr and 89Sr varied at different 89Sr:90Sr ratios. For 0.1 L seawater and 15 min counting time on a low background Hidex liquid scintillation counter (LSC), the MDC of 90Sr was in the range of 1.7-3.5 Bq L−1 and MDC of 89Sr was in the range 0.5-2.4 Bq L−1.