Rapid analytical method of ⁹⁰Sr in urine sample: Rapid separation of Sr by phosphate co-precipitation and extraction chromatography, followed by determination by triple quadrupole inductively coupled plasma mass spectrometry (ICP-MS/MS)

Highlights: • Rapid analytical method was developed for determination of ⁹⁰Sr in urine samples. • ⁹⁰Sr concentration was measured by ICP-MS/MS with 1 mL min⁻¹ of O₂ gas flow rate in collision/reaction cell. • Interferences from Ge, Se and Zr were observed in ⁹⁰Sr determination by ICP-MS/MS. • Strontium was rapidly purified from interfering elements by phosphate co-precipitation and extraction chromatography. • Proposed method was applied to internal dosimetry of workers in a radiological emergency. - Abstract: A rapid analytical method for determining ⁹⁰Sr in urine samples (1–2 L) was developed to assess the internal exposure of workers in a radiological emergency. Strontium in a urine sample was rapidly separated by phosphate co-precipitation, followed by extraction chromatography, and the ⁹⁰Sr activity was determined by triple quadrupole inductively coupled plasma mass spectrometry (ICP-MS/MS). Measurement in the MS/MS mode with an O₂ reaction gas flow rate 1 mL min⁻¹ showed no tailing of ⁸⁸Sr at m/z = 90 up to 50 mg L⁻¹ Sr. The interferences of Ge, Se and Zr at m/z = 90 were successfully removed by phosphate co-precipitation, followed by extraction chromatography with a tandem column of Pre-filter, TRU and Sr resin. This analytical method was validated by the results of the analyses of synthetic urine samples (1.2–1.6 L) containing a known amount of ⁹⁰Sr along with 1 mg of each of Ge, Se, Sr and Zr. The turnaround time for Sr purification from the urine sample and the ⁹⁰Sr measurement by ICP-MS/MS was about 10 h. The detection limit of ⁹⁰Sr was approximately 1 Bq per urine sample, which was lower than 15 Bq per urine after a day of intake giving 5 mSv of unplanned exposure of worker limited by Nuclear Regulation Authority of Japan.