prEN ISO 10704

SLOVENSKI STANDARD
01-oktober-2025
Kakovost vode - Skupna alfa in skupna beta aktivnost - Preskusna metoda z
odlaganjem v tankem sloju (ISO/DIS 10704:2025)
Water quality - Gross alpha and gross beta activity - Test method using thin source
deposit (ISO/DIS 10704:2025)
Wasserbeschaffenheit - Gesamt-Alpha- und Gesamt-Beta-Aktivität -
Dünnschichtverfahren (ISO/DIS 10704:2025)
Qualité de l'eau - Activités alpha globale et bêta globale - Méthode d'essai par dépôt
d'une source fine (ISO/DIS 10704:2025)
Ta slovenski standard je istoveten z: prEN ISO 10704
ICS:
13.060.60 Preiskava fizikalnih lastnosti Examination of physical
vode properties of water
13.280 Varstvo pred sevanjem Radiation protection
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
International
Standard
ISO/DIS 10704
ISO/TC 147/SC 3
Water quality — Gross alpha and
Secretariat: AFNOR
gross beta activity — Test method
Voting begins on:
using thin source deposit
2025-08-27
Qualité de l'eau — Activités alpha globale et bêta globale —
Voting terminates on:
Méthode d'essai par dépôt d'une source fine
2025-11-19
ICS: 13.060.60; 13.280
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Reference number
ISO/DIS 10704:2025(en)
DRAFT
ISO/DIS 10704:2025(en)
International
Standard
ISO/DIS 10704
ISO/TC 147/SC 3
Water quality — Gross alpha and
Secretariat: AFNOR
gross beta activity — Test method
Voting begins on:
using thin source deposit
Qualité de l'eau — Activités alpha globale et bêta globale —
Voting terminates on:
Méthode d'essai par dépôt d'une source fine
ICS: 13.060.60; 13.280
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
This document is circulated as received from the committee secretariat.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
© ISO 2025
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
STANDARDS MAY ON OCCASION HAVE TO
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Published in Switzerland Reference number
ISO/DIS 10704:2025(en)
ii
ISO/DIS 10704:2025(en)
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 2
4 Symbols . 2
5 Principle . 3
6 Chemical reagents and equipment . 3
6.1 Reagents .3
6.1.1 General .3
6.1.2 Standard solutions .3
6.1.3 Wetting or surfactant agents .4
6.1.4 Volatile organic solvents .4
6.1.5 Ultrapure water, with a resistivity of more than 18,2 MΩ cm at 25 °C and total
−1
organic carbon less than 1 μg∙l .4
6.1.6 Specific reagents for alpha-emitting radionuclides co-precipitation .4
6.2 Equipment .4
6.2.1 Laboratory equipment for direct evaporation.4
6.2.2 General equipment .5
6.2.3 Special equipment for alpha-emitting radionuclide co-precipitation .5
6.2.4 Measurement equipment .5
7 Sampling . 5
8 Procedure . 5
8.1 Preliminary .5
8.2 Source preparation .6
8.2.1 Preparation of planchet . .6
8.2.2 Evaporation .6
8.2.3 Co-precipitation .6
8.3 Counting stage .7
8.4 Background and blank determination .7
8.5 Preparation of counting standard for calibration .8
8.6 Preparation of calibration source for self-absorption determination .8
8.6.1 General .8
8.6.2 Spiking one of two test portions .8
8.6.3 Self-absorption curve .8
9 Expression of results . 9
9.1 General .9
9.2 Alpha activity concentration .9
9.3 Beta activity concentration .9
9.4 Standard uncertainty of the alpha activity concentration .10
9.5 Standard uncertainty of the beta activity concentration .11
9.6 Decision threshold . 12
9.6.1 Decision threshold of the alpha activity concentration. 12
9.6.2 Decision threshold of the beta activity concentration . 12
9.7 Limit of detection . 12
9.7.1 Limit of detection of the alpha activity concentration . 12
9.7.2 Limit of detection of the beta activity concentration . 13
9.8 Limits of the coverage intervals . . 13
9.8.1 Limits of the probabilistically symmetric coverage interval . 13
9.8.2 The shortest coverage interval .14
10 Control of interferences . 14

iii
ISO/DIS 10704:2025(en)
10.1 General .14
10.2 Relative humidity .14
10.3 Geometry of the deposit .16
10.4 Crosstalk .16
10.5 Gamma emitters .16
10.6 Low beta energy .16
10.7 Chlorides .16
10.8 Organic matter.16
10.9 Contamination .17
10.10 Losses of activity .17
10.11 Contribution of the natural radionuclides .17
10.12 Losses of activity .17
11 Test report .18
Annex A (informative) Numerical applications . 19
Bibliography .21

iv
ISO/DIS 10704:2025(en)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO [had/had not] received notice of
(a) patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
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For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee [or Project Committee] , , [name of committee],
Subcommittee SC .
This edition cancels and replaces the edition (ISO :), which has been technically revised.
The main changes are as follows:
— Additional information on the measurement strategy
— Storage of the planchet before measurement in a desiccator is no longer a requirement but a
recommendation; other storage methods are possible
— Correction of formulae 19 and 21
— Introduction of coverage intervals in accordance with ISO 11929-1
— Introduction of a curve showing the kinetic of rehydration of the planchet and the impact on the overall
alpha count rate
— Revision of the ‘test report’ chapter
— Correction of the numerical application
A list of all parts in the ISO series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

v
ISO/DIS 10704:2025(en)
Introduction
Radionuclides are present throughout the environment; thus, water bodies (e.g. surface waters, ground
waters, sea waters) contain radionuclides, which can be of either natural or anthropogenic origin:
3 14 40
— naturally occurring radionuclides, including H, C, K and those originating from the thorium and
210 210 222 226 228 227 232 231 234 238
uranium decay series, in particular Pb, Po, Rn, Ra, Ra, Ac, Th, Pa, U, and U
can be found in water bodies due to either natural processes (e.g., desorption from the soil, runoff by rain
water) or released from technological processes involving naturally occurring radioactive materials (e.g.
mining, mineral processing, oil, gas and production, water treatment and the production and the use of
phosphate fertilisers);
55 59 63 90 99
— anthropogenic radionuclides such as Fe, Ni, Ni, Sr, Tc, transuranic elements (Np, Pu, Am,
60 137
and Cm)and some gamma emitting radionuclides such as Co and Cs can also be found in natural
waters. Small quantities of anthropogenic radionuclides can be discharged from nuclear facilities to the
environment as a result of authorized routine releases. The radionuclides present in liquid effluents
[1]
are usually controlled before being discharged to the environment and water bodies. Anthropogenic
radionuclides used in medical and industrial applications can be released to the environment after use.
Anthropogenic radionuclides are also found in waters due to the contamination from fallout resulting
above-ground nuclear detonations and accidents such as those that occurred at the Chornobyl and
Fukushima nuclear facilities.
Radionuclide activity concentrations in water bodies can vary according to local geological characteristics
and climatic conditions and can be locally and temporally enhanced by releases from nuclear facilities
[2][3]
during planned, existing, and emergency exposure situations . Some drinking water sources can thus
contain radionuclides at activity concentrations that could present a human health risk. The World Health
[4]
Organization (WHO) recommends to routinely monitor radioactivity in drinking waters and to take
proper actions when needed to minimize the health risk.
National regulations usually specify the activity concentration limits that are authorized in drinking
waters, water bodies, and liquid effluents to be discharged to the environment. These limits can vary for
planned, existing, and emergency exposure situations. As an example, during either a planned or existing
-1 -1
situation, the WHO guidance level in drinking water is 0,5 Bq·l for gross alpha activity and 1 Bq·l for gross
[4]
beta activity see NOTES 1 and 2. Compliance with these limits is assessed by measuring radioactivity in
water samples and by comparing the results obtained with their associated uncertainties as specified by
[5]
ISO/IEC Guide 98-3 and ISO 5667-20 .
[4]
NOTE 1 If the value is not specified in Annex 6 of Reference , the value has been calculated using the formula
[4] [6] [7]
provided in Reference and the dose coefficient data from References and .
[4] -1
NOTE 2 The guidance level calculated in Reference is the activity concentration with an intake of 2 l∙d of
-1
drinking water for one year, results in an effective dose of 0,1 mSv∙a to members of the public. This is an effective
dose that represents a very low level of risk to human health and which is not expected to give rise to any detectable
[4]
adverse health effects .
This document contains method to support laboratories which need to determine gross alpha activity and
gross beta activity in water samples.
The method described in this document can be used for various types of waters (Clause 1). Minor modifications
such as sample volume and counting time can be made if needed to ensure that the characteristic limit,
decision threshold, detection limit, and uncertainties are below the required limits. This can be done for
several reasons such as emergency situations, lower national guidance limits, and operational requirements.

vi
DRAFT International Standard ISO/DIS 10704:2025(en)
Water quality — Gross alpha and gross beta activity — Test
method using thin source deposit
1 Scope
WARNING — Persons using this document should be familiar with normal laboratory practice. This
document does not purport to address all of the safety problems, if any, associated with its use. It is
the responsibility of the user to establish appropriate safety and health practices.
IMPORTANT — It is absolutely essential that tests conducted according to this document be carried
out by suitably trained staff.
This document specifies a method for the determination of gross alpha and gross beta activity concentration
for alpha- and beta-emitting radionuclides. Gross alpha and gross beta activity measurement is not intended
to give an absolute determination of the activity concentration of all alpha and beta emitting radionuclides
in a test sample, but is a screening analysis to ensure particular reference levels of specific alpha and
beta emitters have not been exceeded. This type of determination is also known as gross alpha and gross
beta index. Gross alpha and gross beta analysis is not expected to be as accurate nor as precise as specific
radionuclide analysis after radiochemical separations.
Maximum beta energies of approximately 0,1 MeV or higher are well measured. It is possible that low energy
3 55 241 14 35 63
beta emitters cannot be detected (e.g. H, Fe, Pu) or can only be partially detected (e.g. C, S, Ni,
210 228
Pb, Ra).
The method covers non-volatile radionuclides, since some gaseous or volatile radionuclides (e.g. radon and
radioiodine) can be lost during the source preparation.
The method is applicable to test samples of drinking water, rainwater, surface and ground water as well as
cooling water, industrial water, domestic and industrial wastewater after proper sampling, sample handling,
and test sample preparation (filtration when necessary and taking into account the amount of dissolved
material in the water).
The method described in this document is applicable in the event of an emergency situation, because the
results can be obtained in less than 1 h. Detection limits reached for gross alpha and gross beta are less
-1 -1
than 10 Bq·l and 20 Bq·l respectively. The evaporation of 10 ml sample is carried out in 20 min followed
by 10 min counting with window-proportional counters. It is the laboratory’s responsibility to ensure the
suitability of this test method for the water samples tested.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 5667-1, Water quality — Sampling — Part 1: Guidance on the design of sampling programmes and sampling
techniques
ISO 5667-3, Water quality — Sampling — Part 3: Preservation and handling of water samples
ISO 9696, Water quality — Gross alpha activity — Test method using thick source
ISO 9697, Water quality — Gross beta activity — Test method using thick source
ISO 11704, Water quality — Gross alpha and gross beta activity — Test method using liquid scintillation counting

ISO/DIS 10704:2025(en)
ISO 11929-1, Determination of the characteristic limits (decision threshold, detection limit and limits of
the coverage interval) for measurements of ionizing radiation — Fundamentals and application — Part 1:
Elementary applications
ISO 11929-2, Determination of the characteristic limits (decision threshold, detection limit and limits of the
coverage interval) for measurements of ionizing radiation — Fundamentals and application — Part 2: Advanced
applications
ISO 11929-3, Determination of the characteristic limits (decision threshold, detection limit and limits of
the coverage interval) for measurements of ionizing radiation — Fundamentals and application — Part 3:
Applications to unfolding methods
ISO 11929-4, Determination of the characteristic limits (decision threshold, detection limit and limits of the
coverage interval) for measurements of ionizing radiation — Fundamentals and application — Part 4: Guidelines
to applications
ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories
ISO 80000-10, Quantities and units — Part 10: Atomic and nuclear physics
ISO/IEC Guide 98-3, Uncertainty of measurement — Part 3: Guide to the expression of uncertainty in
measurement (GUM:1995)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 80000-10 apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— IEC Electropedia: available at http:// www .electropedia .org/
— ISO Online browsing platform: available at http:// www .iso .org/ obp
4 Symbols
Table 1 — Symbols
Symbol Definition Unit
A activity of the calibration source Bq
A activity alpha spiked in sample a, prepared for self-absorption estimation pur- Bq
aα
poses
A activity of the alpha calibration source Bq
α
A activity of the beta calibration source Bq
β
−1
c activity concentration Bq·l
A
# −1
c decision threshold Bq·l
A
⊲ ⊳ −1
c , c lower and upper limits of the probabilistically symmetric coverage interval Bq·l
A A
< > −1
c , c lower and upper limits of the shortest coverage interval Bq·l
A A
f , f self-absorption factor of sample a for α and β, respectively
aα aβ
Φ distribution function of the standardized normal distribution
m mass of the deposit mg
d
m mass of the planchet mg
p
m mass of the planchet and the deposit mg
pd
m mass of the planchet and the filter mg
pf
m mass of the planchet, the filter and the deposit mg
pfd
−1
r , r background count rate from the α and β windows, respectively s
0α 0β
ISO/DIS 10704:2025(en)
TTabablele 1 1 ((ccoonnttiinnueuedd))
Symbol Definition Unit
−1
r self-absorption sample a count rate from the α window s
aα
−1
r , r sample gross count rate from the α and β windows, respectively s
gα gβ
−1
r , r calibration count rate from the α and β windows, respectively s
sα sβ
t background counting time s
t sample counting time s
g
t calibration counting time s
s
−1
U expanded uncertainty calculated by U = k ⋅ u(cA) with k = 1, 2,… Bq·l
−1
u(c ) standard uncertainty associated with the measurement result Bq·l
A
−1
ũ(c ̃ ) standard uncertainty of the estimator cA as a function of an assumed true value Bq·l
A
c ̃_Aof the measurand
-1
w calibration factor L
V volume of test sample L
ε , ε counting efficiency for α and β, respectively
α β
ε , ε counting efficiency of sample a for α and β, respectively
aα aβ
χ alpha-beta crosstalk
T(χ) Uncertainty of the alpha-beta crosstalk
5 Principle
The gross alpha and gross beta activity of the deposit is measured by counting in an alpha- and beta-particle
detector or counting system previously calibrated against alpha- and beta-emitting standards. In order to
obtain a thin and homogeneous deposit directly on a planchet, the sample can be progressively evaporated to
dryness at a temperature below about 85 °C. Alternatively, for the gross alpha determination, radionuclides
can be concentrated via a co-precipitation, the filtered co-precipitate deposited on the planchet being
[8]
measured .
When suspended matter is present, filtration through 0,45 µm filter media is required and the gross alpha
and gross beta activity can also be determined for the material retained on the filter.
IMPORTANT — Gross alpha and gross beta determinations are not absolute determinations of the sample
alpha and beta radioactive contents, but relative determinations referenced to specific alpha and beta
emitters that constitute the standard calibration sources.
6 Chemical reagents and equipment
6.1 Reagents
6.1.1 General
All reagents shall be of recognized analytical grade and shall not contain any detectable alpha and beta
activity, except for radioactive standards solutions.
6.1.2 Standard solutions
6.1.2.1 Alpha standard
The choice of alpha standard depends on the knowledge of the type of radioactive contaminant likely to
be present in the waters being tested. In general, this leads to a choice between naturally occurring and
human-made alpha emitters.
ISO/DIS 10704:2025(en)
Commonly used standards of artificial alpha-emitting radionuclides employed for this purpose are Am
239 239 241
solutions and Pu solutions. When Pu is used, the presence of Pu as an impurity shall be taken into
241 241
account as it leads to growth of Am in prepared standard solutions of sources. When Am is used, take
into account the interferences of its x and γ emission.
NOTE A uranium compound of certified natural or known isotopic composition has one arguable advantage, in
that its specific activity can be calculated from established physical constants and isotopic abundance date which
are independent of the calibration procedures of a particular organization. However, a uranium compound of known
isotopic composition is difficult to obtain. Furthermore, since the energies of the alpha emissions from uranium
isotopes are less than those from the artificial transuranic nuclides, the use of a uranium standard tends to give a high
result for transuranic elements.
6.1.2.2 Beta standard
The choice of beta standard depends on knowledge of the type of radioactive contaminant likely to be
present in the waters being tested.
As a natural material, K as potassium chloride, dried to constant mass at 105 °C, can be used. Standard
solutions of artificial beta-emitting radionuclides 90Sr/Y in equilibrium or Cs are commonly used.
6.1.3 Wetting or surfactant agents
6.1.3.1 Vinyl acetate
6.1.4 Volatile organic solvents
6.1.4.1 Ethyl alcohol
6.1.5 Ultrapure water, with a resistivity of more than 18,2 MΩ cm at 25 °C and total organic carbon
−1
less than 1 μg∙l
6.1.6 Specific reagents for alpha-emitting radionuclides co-precipitation
-1
6.1.6.1 Ammonium hydroxide solution, c(NH OH) = 6 mol·l
-1
6.1.6.2 Nitric acid, concentrated, c(HNO ) = 15,8 mol·l
-1
6.1.6.3 Sulfuric acid solution, c(H SO ) = 1 mol·l
2 4
6.1.6.4 Iron carrier, solution of 5 mg of iron per milliltre
6.1.6.5 Barium carrier, solution of 5 mg of barium per millilitre
6.2 Equipment
6.2.1 Laboratory equipment for direct evaporation
Usual laboratory apparatus to store and prepare the sample as specified in ISO 5667-3.
A hot plate, an automatic evaporator or any other appropriate apparatus.

ISO/DIS 10704:2025(en)
6.2.2 General equipment
6.2.2.1 Filters, of pore size 0,45 µm
6.2.2.2 Planchet (counting trays)
The planchet shall be lipped and of stainless steel. The diameter of the planchet is determined taking
account of the detector diameter and source holder dimensions of the counter used. In the specific case of
co-precipitation, an annular support is used to fix the filter on to a filter holder or on to the planchet.
As the source, test portion and standard, is spread directly on to the planchet for evaporation, it is easier to
produce an even deposit on a roughened metal surface; sand blasting or chemical etching can be applied for
this purpose, alternatively, a rippled planchet can be used.
6.2.3 Special equipment for alpha-emitting radionuclide co-precipitation
6.2.3.1 Hot plate with stirring equipment
6.2.3.2 Infrared lamp
6.2.3.3 Vacuum filtration system
6.2.3.4 Filters, of pore size 0,45 µm
6.2.4 Measurement equipment
6.2.4.1 Alpha-beta counter
Gross alpha and gross beta activity can be measured using either a silicon surface barrier (SSB) detector or a
proportional counter (windowless). Ion-implanted Si detectors and window-proportional counters (between
−2 −2
80 µg·cm to 400 µg·cm ) may also be used. Gross alpha and gross beta activity can also be counted using
a silver-activated zinc sulfide scintillation screen and plastic scintillation detector, respectively.
7 Sampling
Sample, handle and store water samples in accordance with ISO 5667-1 and ISO 5667-3. Additional
information on sampling of different types of waters can be found in the relative parts of the ISO 5667
[9] [10] [11] [12] [13] [14] [15]
series ISO 5667-4 ISO 5667-5 ISO 5667-6 ISO 5667-7 ISO 5667-8 ISO 5667-10 ISO 5667-11
[16]
ISO 5667-14 .
The laboratory sample is not usually acidified as the test portion is directly evaporated on the planchet.
Acidification minimizes the loss of radioactive material from solution by adsorption on the wall of the vial,
but is done after filtration, as otherwise it desorbs radioactive material already adsorbed on the particulate
material and, also, increases the salt content of the test sample, and thus the thickness of the deposit. If
necessary, concentrated nitric acid can be used (it is recommended to avoid hydrochloric acid).
8 Procedure
8.1 Preliminary
Calculate the volume of laboratory sample for gross alpha measurement, i.e. the volume of the test portion,
−2
in order to produce a deposit with a surface density lower than 5 mg·cm on the planchet. For deposits of
−2
surface density below 5 mg·cm , self-absorption phenomena can be neglected for gross beta measurement
137 [17]
except when using low energy beta emitter such as Cs for calibration .

ISO/DIS 10704:2025(en)
When using the same deposit for the simultaneous gross alpha and gross beta measurement, the planchet
surface density limit for alpha activity determinations applies.
8.2 Source preparation
IMPORTANT — Due to the ingrowth of radon decay products over time, the results are dependent on the
time elapsed between sample preparation and measurement. For comparison purposes, it is recommended
that the measurement be performed at the same time after the preparation of the sample.
8.2.1 Preparation of planchet
Degrease planchets (6.2.3.2) using a solvent or a surfactant to ensure that the test portion is well distributed
over the entire surface and consequently that there is a deposit of uniform surface density bonded to the
planchets. Some suppliers degrease planchets at the end of a cycle of fabrication and deliver, on demand, a
certificate of attestation.
Planchets that are not to be used immediately should be stored in a desiccator to prevent any modification
by ambient atmosphere in the laboratory. If the planchet are not kept in a desiccator before measurement,
they must be stored away from any dust or other atmospheric particles. After measurement, it is preferable
not to stack them one on top of the other in case a subsequent check is required.
Weigh the planchets before use, and record the mass, m . If a co-precipitation method is used, weigh the
p
filter (6.2.2.1) with the planchet before use, and record the mass, m .
pf
Avoid reuse of planchets to minimize cross-contamination. If the planchets are reused, their freedom from
contamination shall be demonstrated.
8.2.2 Evaporation
Transfer the test portion on to the planchet using automatic or non-automatic equipment with a known
uncertainty (pipette, water distribution system) and carefully evaporate to dryness.
The residue deposited should form a thin layer of uniform surface density to limit self-absorption phenomena
and to ensure similarity with the calibration source geometry.
After cooling the planchets to ambient temperature, weigh them and record the mass, m . The mass
pd
deposited, m , is given by Formula (1)
d
(1)
If hygroscopic salt deposit is expected, refer to 10.2.
To minimize any loss by spitting, maintain the temperature below about 85 °C over the entire planchet
surface to avoid any overheated areas.
Before evaporating the test portion to dryness on the planchet, pre-evaporation can be performed with
appropriate equipment (6.2.1).
A homogeneous deposit is best achieved on etched or sandblasted planchets. If the deposit is not
homogeneously spread, add a wetting agent or surfactant (6.1.3).
8.2.3 Co-precipitation
The recommended working volume is 500 ml.
If a test portion of lower volume is to be analysed, make up to 500 ml with water.
If a test portion of higher volume is to be analysed, concentrate it by evaporation (6.2.1) to 500 ml.
Adjust the pH of the working volume to 7,0 ± 0,5.

ISO/DIS 10704:2025(en)
Add 20 ml of sulfuric acid (6.1.6.3) and boil for 5 min on a hot plate while stirring.
At a temperature of approximately 50 °C, add 1 ml of the barium carrier solution (6.1.6.5) and stir for 30 min.
The barium sulfate precipitates.
Then add 1 ml of the iron carrier solution (6.1.4.1).
Adjust the pH with ammonium hydroxide, (6.1.6.1) drop by drop until iron(III) hydroxide precipitates.
Continue stirring for 30 min.
Filter (6.2.3.4) the co-precipitates.
Place the filter on to the identified planchet and fix it by an annular support to avoid deformation while drying.
Dry at moderate temperature.
After cooling the planchet and the filter to ambient temperature, weigh them and record their mass, mpfd.
Determine the mass deposited, m , using Formula (2):
d
(2)
[8]
NOTE Radium, polonium and actinides co-precipitate quantitatively with barium sulfate or iron(III) hydroxide .
8.3 Counting stage
Following evaporation (8.2.2) or co-precipitation (8.2.3), if the counting is not performed immediately the
planchet with the deposit can be stored in a desiccator.
The measurement of the residue activity on the planchet is performed by counting for an appropriate
duration to reach the required characteristic limits and depending on the test portion and background
count rates.
The counting strategy is based on the objective of the measurement, which depends on the potential
spectrum being monitored, regulatory requirements and the need for reproducible measurements. A short
time after evaporation is often used by laboratories. If the sample contains a high level of radon-222 activity,
it may be advisable not to count the sample immediately after evaporation. If the sample is particularly
rich in radium 226, a measurement carried out just after evaporation will take place at a time when the
activity in the planchet increases significantly. In such a situation, a two-day delay could lead to a significant
increase in activity. In addition, measurement after evaporation on a planchet according to ISO 10704 will
not be comparable to that achieved by direct measurement using liquid scintillation (ISO 11704). In the case
of a cross-test, the two laboratories must agree on these aspects beforehand. As part of a proficiency test or
interlaboratory test, the organiser must give precise instructions on the time between measurement and
evaporation. To monitor natural radionuclides ingrowth or decay (see 10.11), counting procedures should be
repeated periodically over a period of one month. If specific counting condition is applied, it is recommended
to mention it in the report.
When the counting strategy is defined, the laboratory shall apply it systematically for comparison purposes.
8.4 Background and blank determination
Measure the background activity using a clean planchet (6.2.2.2) under conditions representative of the
measurement method. Repeated co
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