Simultaneous radionuclide determination using PSresin: 2in2 and 2in1 tandem configuration

Analyzing mixtures of radionuclides is a complex task. Two situations are the mixtures of ⁸⁹Sr with ⁹⁰Sr and ⁹⁰Sr with plutonium isotopes. The challenge arises in emergency scenarios resulting from accidents where the activity of ⁸⁹Sr is over 20 times higher than that of ⁹⁰Sr, complicating its quantification and requiring delayed measurements. In scenarios involving accidents, both ⁹⁰Sr and plutonium isotopes, may be present within various matrices. Given their distinct elemental properties, separation is typically achieved using different methods, followed by a measurement post-elution through alpha spectrometry and scintillation techniques. Therefore, methods which allow the fast and reliable determination of those mixtures are still required in routine laboratories.

A novel method for the simultaneous determination of radionuclide mixtures using PSresin is introduced. This innovative approach utilizes PSresins in tandem and has been applied to the analysis of ⁸⁹Sr and ⁹⁰Sr, as well as mixtures of ⁹⁰Sr and plutonium isotopes. Two strategies were investigated: using two PSresin in two cartridges and two measurements (2in2); and using two PSresin in a single cartridge and one measurement employing α/β discrimination (2in1). The methods were validated with standard solutions and applied to river water samples, achieving quantification errors below 10 % for both strategies within 5 and 8 h, respectively, from sample reception.

This represents a great improvement for ⁸⁹Sr and ⁹⁰Sr quantification which is achieved in less than 5 h since sample reception reducing the 30 days required by conventional methods. Additionally, the simultaneous measurement of ⁹⁰Sr and plutonium isotopes reduce the number of required analysis to half, reducing the overall time and cost of the analysis.