Rapid Determination of Sr-90 in Urine by MS/MS Mode with O2 as the Cell Gas on Triple Quadrupole Inductively Coupled Plasma Mass Spectrometry (ICP-MS/MS)

<title>Abstract</title> <p>A high-throughput ICP-MS/MS method was developed and validated for rapid determination of Sr-90 in urine to support radiological emergency response. Using an Agilent 8900 ICP-MS/MS with O₂ collision/reaction gas, isobaric interference from Zr-90 was reduced by &gt; 99.999%, while remaining Ge and Se derived interferences in urine were well below the recommended action level of ~ 2.01 ng/L. The method achieved a LOD of 0.035 ng/L (176 Bq/L) with a simple dilution protocol requiring only 0.5 mL of urine. Validation demonstrated biases within ± 5% above 0.100 ng/L and performance comparable to liquid scintillation counting, providing a rapid, robust, and scalable alternative for emergency radiobioassay.</p>