1.1 This test method covers the separation of dissolved radium from water for the purpose of measuring its radioactivity. Although all radium isotopes are separated, the test method is limited to alpha-particle-emitting isotopes by choice of radiation detector. The most important of these radioisotopes are ²²³Ra, ²²⁴Ra, and ²²⁶Ra. The lower limit of concentration to which this test method is applicable is 3.7 × 10^-2 Bq/L (1 pCi/L).

1.2 This test method may be used for absolute measurements by calibrating with a suitable alpha-emitting radioisotope such as ²²⁶ Ra, or for relative methods by comparing measurements with each other. Mixtures of radium isotopes may be reported as equivalent ²²⁶Ra. Information is also provided from which the relative contributions of radium isotopes may be calculated.

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 and health practices and determine the applicability of regulatory limitations prior to use. For a specific precautionary statement, see Section 9.