ASTM D4785 - 20

    Standard Test Method for Low-Level Analysis of Iodine Radioisotopes in Water

    Active Standard ASTM D4785 | Developed by Subcommittee: D19.04

    Book of Standards Volume: 11.02


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    Significance and Use

    5.1 This test method was developed for measuring low levels of radioactive iodine in water. The results of the test may be used to determine if the concentration of several radioisotopes of iodine in the sample exceeds the regulatory limits for drinking water. With suitable counting techniques, sample size, and counting time, a detection limit of less than 0.037 Bq/L (1 pCi/L) is attainable by gamma-ray spectrometry.

    5.2 This test method is intended for the analysis of iodine radioisotopes with half-lives greater than 2 hours, which include 121I, 123I, 124I, 125I, 126I, 129I, 130I, 131I, 132I, 133I, and 135I. The test method was tested according to Practice D2777 using only 131I. The user of this test method is responsible for determining applicability, bias, and precision for the measurement of other iodine radioisotopes.

    1. Scope

    1.1 This test method covers the quantification of low levels of radioactive iodine in water by means of chemical separation and counting with a high-resolution gamma ray detector. Iodine is chemically separated from a 4 L water sample using ion exchange and solvent extraction and is then precipitated as cuprous iodide for counting.

    1.2 The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided for information only and are not considered standard.

    1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. For specific hazard statements, see 8.16, 8.17, 8.18, Section 9, and 13.2.11.

    1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.


    2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.

    ASTM Standards

    D1129 Terminology Relating to Water

    D1193 Specification for Reagent Water

    D2777 Practice for Determination of Precision and Bias of Applicable Test Methods of Committee D19 on Water

    D3370 Practices for Sampling Water from Flowing Process Streams

    D3648 Practices for the Measurement of Radioactivity

    D3649 Practice for High-Resolution Gamma-Ray Spectrometry of Water

    D4448 Guide for Sampling Ground-Water Monitoring Wells

    D5847 Practice for Writing Quality Control Specifications for Standard Test Methods for Water Analysis

    D6001 Guide for Direct-Push Groundwater Sampling for Environmental Site Characterization

    D7282 Practice for Set-up, Calibration, and Quality Control of Instruments Used for Radioactivity Measurements

    D7902 Terminology for Radiochemical Analyses

    Other Documents

    ANSI N42.22 Traceability of Radioactive Sources to the National Institute of Standards and Technology (NIST) and Associated Instrument Quality Control Available from Institute of Electrical and Electronics Engineers, Inc. (IEEE), 445 Hoes Ln., Piscataway, NJ 08854-4141, http://www.ieee.org.


    ICS Code

    ICS Number Code 13.060.50 (Examination of water for chemical substances)

    UNSPSC Code

    UNSPSC Code 41113405(Gamma counters)


    Referencing This Standard
    Link Here
    Link to Active (This link will always route to the current Active version of the standard.)

    DOI: 10.1520/D4785-20

    Citation Format

    ASTM D4785-20, Standard Test Method for Low-Level Analysis of Iodine Radioisotopes in Water, ASTM International, West Conshohocken, PA, 2020, www.astm.org

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