BS ISO 20899:2018 pdf download – Water quality — Plutonium and neptunium — Test method using ICP-MS
This document specifies methods used to determine the concentration of plutonium and neptuniumisotopes in water by inductively coupled plasma mass spectrometry (ICP-MS) (239Pu, 240Pu， 241Puand 237Np).The concentrations obtained can be converted into activity concentrations of the differentisotopes[9].
Due to its relatively short half-life and z38U isobaric interference,238Pu can hardly be measured bythis method.To quantify this isotope, other techniques can be used (ICP-MS with collision-reaction cell,ICP-MS/MS with collision-reaction cell or chemical separation). Alpha spectrometry measurement, asdescribed in IS0 13167[10], is currently used[11].
This method is applicable to all types of water having a saline load less than 1 g-l-1. A dilution of thesample is possible to obtain a solution having a saline load and activity concentrations compatible withthe preparation and the measurement assembly.
A filtration at 0,45 um is needed for determination of dissolved nuclides.Acidification and chemicalseparation of the sample are always needed.
The limit of quantification depends on the chemical separation and the performance of themeasurement device.
This method covers the measurement of those isotopes in water in activity concentrations betweenaround[12][13];
-1 mBq-l-1 to 5 Bq-l-1 for 239Pu, 240Pu and 237Np;-1 Bq-l-1 to 5 Bq-l-1 for 241Pu.
ln both cases, samples with higher activity concentrations than 5 Bql-1 can be measured if a dilution isperformed before the chemical separation.
lt is possible to measure 241Pu following a pre-concentration step of at least 1 000.
2Normative references
The following documents are referred to in the text in such a way that some or all of their contentconstitutes requirements of this document. For dated references, only the edition cited applies.Forundated references, the latest edition of the referenced document (including any amendments) applies.ISO 3696, Water for analytical laboratory use —Specification and test methods
ISO 5667-1，Water quality — Sampling — Part 1:Guidance on the design of sampling programmes andsampling techniques
ISO 5667-3, Water quality —Sampling — Part 3: Preservation and handling of water samples
ISO 5667-10, Water quality — Sampling — Part 10: Guidance on sampling of waste waters
ISO 17294-1:2004, Water quality — Application of inductively coupled plasma mass spectrometry (ICP-MS) — Part 1: General guidelines
ISO 17294-2:2016, Water quality — Application of inductively coupled plasma mass spectrometry (ICP- MS) — Part 2: Determination of selected elements including uranium isotopes
ISO 80000-10, Quantities and units — Part 10: Atomic and nuclear physics
ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories
3 Terms, definitions, symbols and abbreviated terms
For the purposes of this document, the terms, definitions, symbols and abbreviated terms given in
ISO 80000-10 and the following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https://www.iso.org/obp
— IEC Electropedia: available at http://www.electropedia.org/
4 Principle
The principle of measurement of analysis using ICP-MS is described in ISO 17294-1 and ISO 17294-2.
ICP-MS can be used to measure the mass concentrations of plutonium isotopes ( 239 Pu, 240 Pu, 241 Pu) and 237 Np in water samples.
The results can be converted in activity concentrations using conversion factors given in Table 1.
The water sample has to be measured after filtration (at 0,45 μm porosity) for the determination of dissolved radionuclides and a specific chemical separation shall be performed to limit potential interferences due to uranium isotopes [14] . An example of chemical separation is given in Annex A. As described in the ISO 17294 series, a tracer is needed to evaluate the recovery in chemical separation and to perform an isotopic dilution.
A known amount of pure certified tracer standard solution is added to the sample test portion and the calculation of isotope concentration is based on the isotopic ratios. Even if activity certified standard solutions are available, external calibration is not used as it is quite difficult to find mass certified standard solutions of plutonium isotopes ( 239 Pu, 240 Pu, 241 Pu) and 237 Np. For the determination of plutonium isotopes in water, 242 Pu is commonly used but 244 Pu can also be chosen. The chemical yield obtained for plutonium may be applied to neptunium. This may lead to a potential bias that shall be quantified. Other methods should be used such as external calibration, addition of the short lived 239 Np as tracer, standard additions of 237 Np in several tests portions of the sample, etc. BS ISO 20899 pdf download.