This document specifies a method for the measurement of 99Tc in all types of waters by liquid scintillation counting (LSC). The method is applicable to test samples of supply/drinking water, rainwater, surface and ground water, as well as cooling water, industrial water, domestic, and industrial wastewater after proper sampling and handling, and test sample preparation. A filtration of the test sample is necessary. The detection limit depends on the sample volume and the instrument used. The method described in this document, using currently available LSC instruments, has a detection limit of approximately 5 Bq·kg-1 to 20 Bq·kg-1, which is lower than the WHO criteria for safe consumption of drinking water (100 Bq l-1)[3]. These values can be achieved with a counting time of 30 min for a sample volume varying between 14 ml to 40 ml. The method presented in this document is not intended for the determination of ultra-trace amount of 99Tc. The activity concentration values in this document are expressed by sample mass unit instead of sample volume unit as it is usually the case in similar standards. The reason is that 99Tc is measured in various matrix types such as fresh water or sea water, which have significant differences in density. The activity concentration values can be easily converted to sample volume unit by measuring the sample volume. However, it increases the uncertainty on the activity concentration result. The method described in this document is applicable in the event of an emergency situation, but not if 99mTc is present at quantities that could cause interference and not if 99mTc is used as a recovery tracer. The analysis of Tc adsorbed to suspended matter is not covered by this method. It is the user's responsibility to ensure the validity of this test method for the water samples tested.
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Foreword
Introduction
1 Scope
2 Normative references
3 Terms, definitions and symbols
4 Principle
5 Sampling and storage
6 Procedure
6.1 Sample preparation for measurement
6.2 Sample measurement
7 Quality assurance and quality control program
7.1 General
7.2 Variables that could influence the measurement
7.3 Instrument verification
7.4 Contamination
7.5 Interference control
7.6 Method verification
7.7 Demonstration of analyst capability
7.8 Sample measurement
8 Expression of results
8.1 Sample activity, recovery and uncertainties
8.2 Decision threshold
8.3 Detection limit
8.4 Confidence interval limits
8.5 Calculation using the activity per unit of volume
8.6 Conversion of activity concentration to mass concentration
8.7 Conversion of mass concentration to volume unit
9 Test report
Annex A Method 1 — TEVA11 TEVA resin is the trademark of a product supplied by Eichrom Technologies and TrisKem international. This information is given for the convenience of users of this document and does not constitute an endorsement by ISO of the product named. Equivalent products may be used if they can be shown to lead to the same results. resin (informative)
Annex B Method 2 — TRU22 TRU resin is the trademark of a product supplied by Eichrom Technologies and TrisKem international. This information is given for the convenience of users of this document and does not constitute an endorsement by ISO of the product named. Equivalent products may be used if they can be shown to lead to the same results. resin (informative)
Annex C Method 3 — Anion exchange resin (informative)
7.2 Variables that could influence the measurement
7.3 Instrument verification
7.4 Contamination
7.5 Interference control
7.6 Method verification
7.7 Demonstration of analyst capability
7.8 Sample measurement
8 Expression of results
8.1 Sample activity, recovery and uncertainties
8.2 Decision threshold
8.3 Detection limit
8.4 Confidence interval limits
8.5 Calculation using the activity per unit of volume
8.6 Conversion of activity concentration to mass concentration
8.7 Conversion of mass concentration to volume unit
9 Test report
Annex A Method 1 — TEVA11 TEVA resin is the trademark of a product supplied by Eichrom Technologies and TrisKem international. This information is given for the convenience of users of this document and does not constitute an endorsement by ISO of the product named. Equivalent products may be used if they can be shown to lead to the same results. resin (informative)
Annex B Method 2 — TRU22 TRU resin is the trademark of a product supplied by Eichrom Technologies and TrisKem international. This information is given for the convenience of users of this document and does not constitute an endorsement by ISO of the product named. Equivalent products may be used if they can be shown to lead to the same results. resin (informative)
Annex C Method 3 — Anion exchange resin (informative)
ISO 10703:2007 Water quality -- Determination of the activity concentration of radionuclides -- Method by high resolution gamma-ray spectrometry
ISO 11929:2010 Determination of the characteristic limits (decision threshold, detection limit and limits of the confidence interval) for measurements of ionizing radiation -- Fundamentals and application
ISO 19361:2017 Measurement of radioactivity -- Determination of beta emitters activities -- Test method using liquid scintillation counting
ISO 10703:2007 Water quality -- Determination of the activity concentration of radionuclides -- Method by high resolution gamma-ray spectrometry
ISO 11929:2010 Determination of the characteristic limits (decision threshold, detection limit and limits of the confidence interval) for measurements of ionizing radiation -- Fundamentals and application
ISO 19361:2017 Measurement of radioactivity -- Determination of beta emitters activities -- Test method using liquid scintillation counting
ISO 20042:2019 Measurement of radioactivity -- Gamma-ray emitting radionuclides -- Generic test method using gamma-ray spectrometry
ISO 3696:1987 Water for analytical laboratory use -- Specification and test methods
ISO 5667-10:1992 Water quality -- Sampling -- Part 10: Guidance on sampling of waste waters
ISO 5667-1:2006 Water quality -- Sampling -- Part 1: Guidance on the design of sampling programmes and sampling techniques
ISO 5667-3:2018 Water quality -- Sampling -- Part 3: Preservation and handling of water samples
ISO 80000-10 Quantities and units -- Part 10: Atomic and nuclear physics
ISO 80000-10:2019 Quantities and units — Part 10: Atomic and nuclear physics
ISO/IEC 17025:2017 General requirements for the competence of testing and calibration laboratories
ISO/IEC Guide 98-3:2008 Uncertainty of measurement -- Part 3: Guide to the expression of uncertainty in measurement (GUM:1995)
ISO/IEC Guide 99:2007 International vocabulary of metrology -- Basic and general concepts and associated terms (VIM)