ISO 13162:2011 pdf download.Water quality —Determination of carbon 14 activity - Liquid scintillation counting method.
A prerequisite for the direct determination of 14C in a water sample is the absence of or a negligible contribution from other beta-emitting radionuclides, such as 90Sr and Ra isotopes. When the radionuclide content of the sample is unknown, the method specified in this International Standard only provides a ‘4C equivalent actMty for the sample
Examples of methods of sample pretreatment are described in Annexes C and D.
Concerning quench correction, if particular conditions of chemical quenching affect the measurement results, it is recommended that a quench curve be established. It is important to choose the chemical quenching agent in accordance with the supposed type of quenching observed in the sample.
5 Reagents and equipment
5.1 Reagents
During the analysis, unless otherwise stated, use only reagents of recognized analytical grade,
5.1.1 Reference water for the blank
The reference water for the blank should be as free as possible of chemical or radioactive impurities.
The reference water may have a low 14C activity concentration, in becquerels per litre, at the time i at which the samples are measured.
For example, obtain water with a 14C activity concentration as low as possible, e.g. (deep) subterranean water. Distil the water. Keep the distillate in a well-sealed borosalicate glass bottle in the dart at a temperature as constant as possible this reference water shall be kept physicall’y remote from any 14C-containing material (see next paragraph). Determine (see final paragraph) the 14C activity concentration (t = 0), in becquerels per litre, of this water and note the date (s = 0)of this determination.
Examples of methods of sample pretreatment are described in Annexes C and D.
Concerning quench correction, if particular conditions of chemical quenching affect the measurement results, it is recommended that a quench curve be established. It is important to choose the chemical quenching agent in accordance with the supposed type of quenching observed in the sample.
5 Reagents and equipment
5.1 Reagents
During the analysis, unless otherwise stated, use only reagents of recognized analytical grade,
5.1.1 Reference water for the blank
The reference water for the blank should be as free as possible of chemical or radioactive impurities.
The reference water may have a low 14C activity concentration, in becquerels per litre, at the time i at which the samples are measured.
For example, obtain water with a 14C activity concentration as low as possible, e.g. (deep) subterranean water. Distil the water. Keep the distillate in a well-sealed borosalicate glass bottle in the dart at a temperature as constant as possible this reference water shall be kept physicall’y remote from any 14C-containing material (see next paragraph). Determine (see final paragraph) the 14C activity concentration (t = 0), in becquerels per litre, of this water and note the date (s = 0)of this determination.
