Radiostrontium separation from sodium molybdate solution and its measurement using LSA: an application to radiopharmaceutical analysis

Abstract

Technetium ( 99m Tc), a decay product of molybdenum ( 99 Mo), is employed as radioisotope in nuclear medicine. Several practical devices known as generators are commercially available which enable the user to separate the daughter from the parent radionuclide. The present study is focused on quality control of chro- matographic technetium generator. A properly constructed generator should comply with international requirements of radionuclide purity of 90 Sr/ 99 Mo B 6 9 10 -8 and 89 Sr/ 99 Mo B 6 9 10 -7 . For this purpose an analytical method was optimized to quantify radiostrontium ( 89 Sr and 90 Sr) in sodium molybdate (Na2 MoO4) solution, a fission product used for 99 Mo/ 99m Tc generators. Dowex 1 9 8 and alumina were used in sequence followed by tributyl phosphate extraction for radiostrontium separation. Cerenkov measurement of 89 Sr and 90 Sr (through its descendent 90 Y) was performed using Perkin Elmer Tricarb LSA 3170 with detection efficiency of 42 and 14 %, respectively. Since efficiency of Cerenkov counting is sensitive to presence of color, spectral index of sample was used to correct the counting efficiency. The chemical recovery for strontium was 22 % and for yttrium was 80 % as determined by inductively coupled plasma optical emission spectrometry. Lower limit of detection was found to be 6.3 and 14.4 Bq L -1 for 90 Sr and 89 Sr, respectively with 60 min counting time. Hence method can be applied successfully to analyze 89,90 Sr in fission molybdenum used as radiopharmaceutical with a relative error of \10 %.