Water quality - Determination of tritium activity concentration - Liquid scintillation counting method (ISO 9698:2010)

ISO 9698:2010 specifies the conditions for the determination of tritium activity concentration in samples of environmental water or of tritiated water using liquid scintillation counting.
The choice of the analytical procedure, either with or without distillation of the water sample prior to determination, depends on the aim of the measurement and the sample characteristics.
Direct measurement of a raw water sample using liquid scintillation counting has to consider the potential presence of other beta emitter radionuclides. To avoid interference with these radionuclides when they are detected, the quantification of tritium will be performed following the sample treatment by distillation. Three distillation procedures are described.
The method is not applicable to the analysis of organically bound tritium; its determination requires additional chemical processing (such as chemical oxidation or combustion).
With suitable technical conditions, the detection limit may be as low as 1 Bq l-1. Tritium activity concentrations below 106 Bq l-1 can be determined without any sample dilution. A prior enrichment step can significantly lower the limit of detection.

Wasserbeschaffenheit - Bestimmung der Aktivitätskonzentration von Tritium - Verfahren mit dem Flüssigszintillationszähler (ISO 9698:2010)

Diese Internationale Norm legt ein Verfahren zur Bestimmung der Aktivitätskonzentration von Tritium in natürlichen Wasserproben oder von tritiiertem Wasser ([3H]H2O) mithilfe eines Flüssigszintillationszählers fest.
Die Auswahl des analytischen Verfahrens, ob mit oder ohne Destillation der Wasserprobe vor der Bestimmung, hängt vom Ziel der Messung sowie von den Eigenschaften der Probe ab (siehe [1], [2], [3]).
Bei der Direktmessung von Rohwasserwasserproben mithilfe des Flüssigszintillationszählers muss das potenzielle Vorhandensein von Beta-Strahlen emittierenden Radionukliden berücksichtigt werden. Um bei Feststellung solcher Radionuklide Störungen mit diesen zu vermeiden, wird die Tritiumquantifizierung nach der Probenbehandlung durch Destillation durchgeführt (siehe [4], [5], [6], [7]). Drei Destillationsverfahren werden in den Anhängen B, D und E beschrieben.
Dieses Verfahren eignet sich nicht für die Analyse von organisch gebundenem Tritium. Diese Bestimmung erfordert weitere chemische Aufarbeitung (wie eine chemische Oxidation oder Verbrennung).
Unter geeigneten technischen Voraussetzungen liegt die Nachweisgrenze bei gerade einmal 1 Bq l-1. Aktivitätskonzentrationen von Tritium unter 106 Bq l-1 können ohne Probenverdünnung bestimmt werden. Eine vorherige Anreicherung kann die Nachweisgrenze beträchtlich senken (siehe [8], [9]).

Qualité de l'eau - Détermination de l'activité volumique du tritium - Méthode par comptage des scintillations en milieu liquide (ISO 9698:2010)

L'ISO 9698:2010 spécifie les conditions de détermination de l'activité volumique du tritium dans des échantillons d'eau environnementale ou d'eau tritiée par comptage des scintillations en milieu liquide.
Le choix du mode opératoire analytique, avec ou sans distillation de l'échantillon d'eau avant la détermination, dépend du but du mesurage et des caractéristiques de l'échantillon.
Le mesurage direct d'un échantillon d'eau brute par comptage des scintillations en milieu liquide doit prendre en compte la présence potentielle d'autres radionucléides émetteurs bêta. Pour éviter des interférences avec ces radionucléides lorsqu'ils sont détectés, la quantification du tritium est effectuée après avoir traité l'échantillon par distillation. Trois modes opératoires de distillation sont décrits.
Cette méthode n'est pas applicable à l'analyse du tritium organiquement lié; sa détermination nécessite un traitement chimique supplémentaire (telle une oxydation chimique ou une combustion).
Dans les conditions techniques adéquates, la limite de détection peut être réduite à 1 Bq l-1. Les activités volumiques du tritium inférieures à 106 Bq l-1 peuvent être déterminées sans dilution de l'échantillon. Une étape d'enrichissement préalable peut abaisser de manière significative la limite de détection.

Kakovost vode - Določevanje koncentracije aktivnosti tritija - Metoda štetja s tekočinskim scintilatorjem (ISO 9698:2010)

Ta mednarodni standard opisuje pogoje za določevanje koncentracije aktivnosti tritija v vzorcih okoljske vode ali tritirane vode s štetjem s tekočinskim scintilatorjem. Izbira analitskega postopka z destilacijo ali brez destilacije vzorca vode pred določevanjem je odvisna od cilja merjenja in lastnosti vzorca. Pri neposredni meritvi vzorca neobdelane vode s štetjem s tekočinskim scintilatorjem je treba upoštevati potencialno prisotnost drugih beta oddajnih radionuklidov. Za preprečevanje interference s temi radionuklidi, ko se zaznajo, se po obdelavi vzorca z destilacijo izvede kvantifikacija tritija. V dodatkih B, D in E so opisani trije postopki destilacije. Metoda se ne uporablja za analizo organsko vezanega tritija, ki za določevanje zahteva dodatno kemično predelavo (na primer kemično oksidacijo ali zgorevanje). Pod primernimi tehničnimi pogoji je lahko meja detekcije nizka, in sicer do 1 Bq/l. Koncentracije aktivnosti tritija pod 106 Bq/l se lahko določijo brez redčenja vzorca. Predhodni korak obogatitve lahko znatno zniža mejo detekcije.

General Information

Status
Withdrawn
Publication Date
21-Jul-2015
Withdrawal Date
28-May-2019
Technical Committee
Drafting Committee
Current Stage
9960 - Withdrawal effective - Withdrawal
Completion Date
29-May-2019

RELATIONS

Buy Standard

Standard
EN ISO 9698:2015
English language
32 pages
sale 10% off
Preview
sale 10% off
Preview

e-Library read for
1 day

Standards Content (sample)

SLOVENSKI STANDARD
SIST EN ISO 9698:2015
01-oktober-2015
.DNRYRVWYRGH'RORþHYDQMHNRQFHQWUDFLMHDNWLYQRVWLWULWLMD0HWRGDãWHWMDV
WHNRþLQVNLPVFLQWLODWRUMHP ,62

Water quality - Determination of tritium activity concentration - Liquid scintillation

counting method (ISO 9698:2010)

Wasserbeschaffenheit - Bestimmung der Aktivitätskonzentration von Tritium - Verfahren

mit dem Flüssigszintillationszähler (ISO 9698:2010)

Qualité de l'eau - Détermination de l'activité volumique du tritium - Méthode par

comptage des scintillations en milieu liquide (ISO 9698:2010)
Ta slovenski standard je istoveten z: EN ISO 9698:2015
ICS:
13.060.60 Preiskava fizikalnih lastnosti Examination of physical
vode properties of water
SIST EN ISO 9698:2015 en,de

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

---------------------- Page: 1 ----------------------
SIST EN ISO 9698:2015
---------------------- Page: 2 ----------------------
SIST EN ISO 9698:2015
EUROPEAN STANDARD
EN ISO 9698
NORME EUROPÉENNE
EUROPÄISCHE NORM
July 2015
ICS 13.080; 13.060.60
English Version
Water quality - Determination of tritium activity concentration -
Liquid scintillation counting method (ISO 9698:2010)

Qualité de l'eau - Détermination de l'activité volumique du Wasserbeschaffenheit - Bestimmung der

tritium - Méthode par comptage des scintillations en milieu Aktivitätskonzentration von Tritium - Verfahren mit dem

liquide (ISO 9698:2010) Flüssigszintillationszähler (ISO 9698:2010)
This European Standard was approved by CEN on 16 July 2015.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European

Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national

standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by translation

under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same

status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,

Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,

Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United

Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels

© 2015 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 9698:2015 E

worldwide for CEN national Members.
---------------------- Page: 3 ----------------------
SIST EN ISO 9698:2015
EN ISO 9698:2015 (E)
Contents Page

European foreword .............................................................................................................................................3

---------------------- Page: 4 ----------------------
SIST EN ISO 9698:2015
EN ISO 9698:2015 (E)
European foreword

The text of ISO 9698:2010 has been prepared by Technical Committee ISO/TC 147 “Water quality” of the

International Organization for Standardization (ISO) and has been taken over as EN ISO 9698:2015 by

Technical Committee CEN/TC 230 “Water analysis” the secretariat of which is held by DIN.

This European Standard shall be given the status of a national standard, either by publication of an identical

text or by endorsement, at the latest by January 2016, and conflicting national standards shall be withdrawn at

the latest by January 2016.

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent

rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.

According to the CEN-CENELEC Internal Regulations, the national standards organizations of the following

countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech

Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece,

Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal,

Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom.

Endorsement notice

The text of ISO 9698:2010 has been approved by CEN as EN ISO 9698:2015 without any modification.

---------------------- Page: 5 ----------------------
SIST EN ISO 9698:2015
---------------------- Page: 6 ----------------------
SIST EN ISO 9698:2015
INTERNATIONAL ISO
STANDARD 9698
Second edition
2010-12-15
Water quality — Determination of tritium
activity concentration — Liquid
scintillation counting method
Qualité de l'eau — Détermination de l'activité volumique du tritium —
Méthode par comptage des scintillations en milieu liquide
Reference number
ISO 9698:2010(E)
ISO 2010
---------------------- Page: 7 ----------------------
SIST EN ISO 9698:2015
ISO 9698:2010(E)
PDF disclaimer

This PDF file may contain embedded typefaces. In accordance with Adobe's licensing policy, this file may be printed or viewed but

shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editing. In

downloading this file, parties accept therein the responsibility of not infringing Adobe's licensing policy. The ISO Central Secretariat

accepts no liability in this area.
Adobe is a trademark of Adobe Systems Incorporated.

Details of the software products used to create this PDF file can be found in the General Info relative to the file; the PDF-creation

parameters were optimized for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In

the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below.

COPYRIGHT PROTECTED DOCUMENT
© ISO 2010

All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,

electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or

ISO's member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2010 – All rights reserved
---------------------- Page: 8 ----------------------
SIST EN ISO 9698:2015
ISO 9698:2010(E)
Contents Page

Foreword ............................................................................................................................................................iv

Introduction.........................................................................................................................................................v

1 Scope......................................................................................................................................................1

2 Normative references............................................................................................................................1

3 Symbols, definitions and units ............................................................................................................2

4 Principle .................................................................................................................................................3

5 Reagents and equipment......................................................................................................................3

6 Sampling and samples..........................................................................................................................5

7 Procedure...............................................................................................................................................6

8 Expression of results............................................................................................................................8

9 Test report............................................................................................................................................10

Annex A (informative) Numerical applications ...............................................................................................12

Annex B (informative) Distillation of large volume sample ...........................................................................14

Annex C (informative) Internal standard methods .........................................................................................17

Annex D (informative) Distillation of small volume sample...........................................................................19

Annex E (informative) Screening method for wet matrices...........................................................................22

Bibliography......................................................................................................................................................24

© ISO 2010 – All rights reserved iii
---------------------- Page: 9 ----------------------
SIST EN ISO 9698:2015
ISO 9698:2010(E)
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.

International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.

The main task of technical committees is to prepare International Standards. Draft International Standards

adopted by the technical committees are circulated to the member bodies for voting. Publication as an

International Standard requires approval by at least 75 % of the member bodies casting a vote.

Attention is drawn to the possibility that some of the elements of this document may be the subject of patent

rights. ISO shall not be held responsible for identifying any or all such patent rights.

ISO 9698 was prepared by Technical Committee ISO/TC 147, Water quality.

This second edition cancels and replaces the first edition (ISO 9698:1989), which has been technically

revised.
iv © ISO 2010 – All rights reserved
---------------------- Page: 10 ----------------------
SIST EN ISO 9698:2015
ISO 9698:2010(E)
Introduction

The tritium present in the environment is of natural origin and man made. As a result of atmospheric nuclear

weapon testing, emissions from nuclear engineering installations, and the application and processing of

isotopes, relatively large amounts of tritium have been released to the environment. Despite the low dose

factor associated to tritium, monitoring of tritium activity concentrations in the environment is necessary in

order to follow its circulation in the hydrosphere and biosphere.
© ISO 2010 – All rights reserved v
---------------------- Page: 11 ----------------------
SIST EN ISO 9698:2015
---------------------- Page: 12 ----------------------
SIST EN ISO 9698:2015
INTERNATIONAL STANDARD ISO 9698:2010(E)
Water quality — Determination of tritium activity
concentration — Liquid scintillation counting method

WARNING — This International Standard 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 and to ensure compliance with any national regulatory conditions.

IMPORTANT — It is absolutely essential that tests conducted according to this International Standard

be carried out by suitably trained staff.
1 Scope

This International Standard specifies the conditions for the determination of tritium activity concentration in

samples of environmental water or of tritiated water ([ H]H O) using liquid scintillation counting.

The choice of the analytical procedure, either with or without distillation of the water sample prior to

determination, depends on the aim of the measurement and the sample characteristics (see References [1],

[2], [3]).

Direct measurement of a raw water sample using liquid scintillation counting has to consider the potential

presence of other beta emitter radionuclides. To avoid interference with these radionuclides when they are

detected, the quantification of tritium will be performed following the sample treatment by distillation (see

References [4], [5], [6], [7]). Three distillation procedures are described in Annexes B, D and E.

The method is not applicable to the analysis of organically bound tritium; its determination requires additional

chemical processing (such as chemical oxidation or combustion).

With suitable technical conditions, the detection limit may be as low as 1 Bq l . Tritium activity concentrations

6 −1

below 10 Bq l can be determined without any sample dilution. A prior enrichment step can significantly

lower the limit of detection (see References [8], [9]).
2 Normative references

The following referenced documents are indispensable for the application 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: Guidance on the preservation and handling of water

samples

ISO 5667-14, Water quality — Sampling — Part 14: Guidance on quality assurance of environmental water

sampling and handling
ISO 80000-10, Quantities and units — Part 10: Atomic and nuclear physics

ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories

© ISO 2010 – All rights reserved 1
---------------------- Page: 13 ----------------------
SIST EN ISO 9698:2015
ISO 9698:2010(E)

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)
3 Symbols, definitions and units

For the purposes of this document, the definitions, symbols and units defined in ISO 80000-10,

ISO/IEC Guide 98-3 and ISO/IEC Guide 99, as well as the following symbols, apply.

Maximum energy for the beta emission, in kilo-electronvolts
max
V Volume of test sample, in litres
m Mass of test sample, in kilograms
Mass density of the sample, in grams per litre
c Activity concentration, in becquerels per litre
a Activity per unit of mass, in becquerels per kilogram
A Activity of the calibration source, in becquerels
t Background counting time, in seconds
t Sample counting time, in seconds
t Calibration counting time, in seconds
n Number of repetitions
r Background count rate in the repetition i, per second
r Mean background count rate for i repetitions, per second
r Sample count rate in the repetition i, per second
r Mean sample count rate for i repetitions, per second
r Calibration count rate, per second
Detection efficiency

Efficiency measured for each of the working standards to elaborate the quench curve

f Quench factor

u(c ) Standard uncertainty associated with the measurement result, in becquerels per litre

Expanded uncertainty, calculated by U = k ⋅ u(c ) with k = 1, 2,…, in becquerels per litre

Decision threshold, in becquerels per litre
Detection limit, in becquerels per litre
Lower and upper limits of the confidence interval, in becquerels per litre
cc,
A A
2 © ISO 2010 – All rights reserved
---------------------- Page: 14 ----------------------
SIST EN ISO 9698:2015
ISO 9698:2010(E)
4 Principle

The test portion is mixed with the scintillation cocktail in a counting vial to obtain a homogeneous medium.

Electrons emitted by tritium transfer their energy to the scintillation medium. Molecules excited by this process

return to their ground state by emitting photons that are detected by photodetectors.

The electric pulses emitted by the photodetectors are amplified, sorted (in order to remove random events)

and analysed by the electronic systems and the data analysis software. The count rate of these photons

allows the determination of the test portion activity, after correcting for the background count rate and

detection efficiency.

In order to determine the background count rate, a blank sample is prepared in the same way as the test

portion. The blank sample is prepared using a reference water of the lowest activity available, also sometimes

called “dead water”.

The detection efficiency is determined with a sample of a standard of aqueous tritium (calibration source), or a

dilution of this standard with water for the blank, measured in the same conditions as the test portion.

The conditions to be met for the blank sample, the test portion and the calibration source are the following:

⎯ same type of counting vial;
⎯ same filling geometry;
⎯ same ratio between test portion and scintillation cocktail;
⎯ temperature stability of the detection equipment;
⎯ value of quench indicating parameter included in calibration curve.

IMPORTANT — Quench correction: If the measurement results are affected by particular conditions of

chemical quenching, it is recommended that a quench curve be established. It is important to choose

a suitable chemical quenching agent for the type of quenching suspected in the sample.

NOTE For high activity and highly quenched samples, it may be practical to use an internal standard method, as

described in Annex C.
5 Reagents and equipment
Use only reagents of recognized analytical grade.
5.1 Reagents
5.1.1 Water for the blank

The water used for the blank shall be as free as possible of chemical impurities to avoid quenching, of

radioactive impurities (see Reference [10]) and with an activity concentration of tritium negligible in

comparison with the activities to be measured.

For example, a water sample with a low tritium activity concentration can be obtained from (deep)

subterranean water kept in a well-sealed borosilicate glass bottle in the dark at a controlled temperature

(ISO 5667-3). This blank water sample shall be kept physically remote from any tritium-containing material

(see Clause 4, important notice). Determine the tritium activity concentration (t = 0), in Bq l , of this water and

note the date (t = 0) of this determination (see Clause 4, Note).
© ISO 2010 – All rights reserved 3
---------------------- Page: 15 ----------------------
SIST EN ISO 9698:2015
ISO 9698:2010(E)

It is advisable to keep an adequate quantity of blank water in stock and to make small working amounts from it

for immediate use, as required. Contamination with tritium (e.g. from water vapour in the air and from tritium

sources such as luminous watches and gas chromatographs) or other radioactive species should be avoided.

As the activity is becoming non-negligible for activities around 1 Bq l , it is necessary to use a blank water

measured to ensure the “absence” of tritium. The tritium activity concentration in the blank water can be

determined by enrichment followed by liquid scintillation counting or from the measurement of He by mass

spectrometry. Preferably use blank water with a tritium activity concentration of less than 0,5 Bq l .

When the volume of blank water is sufficiently large, e.g. 10 l to 20 l, and well-sealed, tritium activity

concentration will remain stable for years, although it is advisable to determine the tritium activity

concentration at predetermined intervals, e.g. every year.
5.1.2 Calibration source solution

In order to avoid cross-contamination, prepare, in a suitable location which is remote from the area where the

tritium analyses are to be carried out, weigh and pour into a weighed volumetric flask (for example, 100 ml)

the requisite quantity of a concentrated tritium ([ H]H O) standard solution, so that the tritium activity

concentration will generate sufficient counts to reach the required measurement uncertainty after dilution with

blank water and thorough mixing. Calculate the tritium activity concentration of the resulting calibration source

solution (t = 0). Note the date at which the standard solution was made up (t = 0).

The tritium activity concentration of the calibration source solution at time t at which the samples are

measured must be corrected for radioactive decay.
5.1.3 Scintillation solution

The scintillation cocktail is chosen according to the characteristics of the sample to be analysed and according

to the properties of the detection equipment (see Reference [11]).

It is recommended to use a good hydrophilic scintillation cocktail, especially for the measurement of usual

environmental water.

The characteristics of the scintillation cocktail must allow the mixture to be homogeneous and stable.

For the direct measurement of raw waters containing particles in suspension, it is recommended that a

scintillation cocktail leading to a gel-type mixture be used.
It is recommended to:

⎯ store in the dark and, particularly just before use, avoid exposure to direct sunlight or fluorescent light in

order to prevent interfering luminescence;

⎯ comply with the storage conditions specified by the scintillation cocktail supplier.

The mixtures (scintillation cocktail and test sample) should be disposed of as chemical waste, and, depending

on the radioactivity, may require disposal as radioactive waste.
5.1.4 Quenching agent

The following are examples of chemical quenching agents: nitric acid, acetone, organochloride compounds,

nitromethane.
NOTE Some quenching agents are dangerous or toxic.
4 © ISO 2010 – All rights reserved
---------------------- Page: 16 ----------------------
SIST EN ISO 9698:2015
ISO 9698:2010(E)
5.2 Equipment

Laboratory equipment, such as pipettes and balances, shall be employed that enables the expected/agreed

data quality objectives to be achieved, as well as the quantification of the uncertainty attached to the

measurement.

NOTE Control of the quantity of liquid scintillation cocktail used in source preparation is essential to achieve

consistent data quality.
5.2.1 Liquid scintillation counter

Liquid scintillation counter, preferably with an automatic sample transfer. Operation at constant temperature is

recommended following the manufacturer's instructions. Depending on the limit of detection to be reached, a

liquid scintillation counter with a low-level configuration may be needed. The method specified in this

International Standard relates to the widely used liquid scintillation counters with vials that hold about 20 ml.

When other vials are used with appropriate counters, the described method shall be adapted accordingly.

5.2.2 Counting vials

Different types of scintillation vials exist, manufactured using a range of materials. The most common are

glass vials and polyethylene vials. Glass vials allow visual inspection of the scintillation medium, but have an

inherent background, due to the presence of K. However, some organic solvents contained in scintillation

cocktails diffuse through the polyethylene, accelerating the degradation of the mixture.

Other types of vials exist:

⎯ glass vials with low level of K, will exhibit a lower background than “normal” glass vials;

⎯ for the determination of very low tritium concentration, the use of polytetrafluoroethylene (PTFE) vials or

polyethylene vials with an inner layer of PTFE on the inside vial wall is strongly recommended. Diffusion

of organic solvents is then slower through PTFE than through polyethylene. These vials are used for long

counting times with very low-level activity to be measured.

Generally, the vials are single use. If the vial is reused, it is necessary to apply an efficient cleaning procedure.

To prevent interfering luminescence, the counting vials should be kept in the dark and should not be exposed

to direct sunlight or fluorescent light, particularly just before use.

Toluene-based scintillation solutions may physically distort polyethylene and should therefore not be used in

combination with polyethylene counting vials. Diffusion of organic solvents into and through the polyethylene

walls is also a serious drawback of polyethylene vials.
6 Sampling and samples
6.1 Sampling
Conditions of sampling shall conform to ISO 5667-1.

It is not advised to acidify the sample due to the high chemical quench caused by acids, and the potential

presence of tritium in the acid, as specified in ISO 5667-3.

It is important that the laboratory receive a representative sample, unmodified during the transport or storage

and in an undamaged container. It is recommended to use a glass flask and to fill it to the maximum, to

minimize tritium exchange with the atmospheric moisture.

For low level activity measurements, it is important to avoid any contact between sample and atmosphere

during the sampling.
© ISO 2010 – All rights reserved 5
---------------------- Page: 17 ----------------------
SIST EN ISO 9698:2015
ISO 9698:2010(E)
6.2 Sample storage

If required, the sample shall be stored in compliance with ISO 5667-3. If the storage duration exceeds that

specified in ISO 5667-3, it is advisable to store the samples in glass flasks.
7 Procedure
7.1 Sample preparation
7.1.1 Direct procedure

Measurement of the test sample is generally performed on raw water without removal of suspended matter. If

the activity of a filtered or centrifuged sample is to be measured, the removal of suspended matter shall be

performed as soon as possible after the sampling (see ISO 5667-3).
7.1.2 Distillation
Examples of distillation procedures are given in Annexes B, D and E.
Distillation shall avoid isotopic fractionation (see Reference [12]).

Distillation or any other physic-chemical treatment of water is not appropriate for simultaneous measurement

of tritium and C.
7.2 Preparation of the sources to be measured

Known quantity of test sample and scintillation cocktail are introduced into the counting vial.

After closing the vial, it shall be thoroughly shaken to homogenize the mixture.

The vial identification shall be written on the top of the vial stopper. The storage time depends upon the

scintillation mixture, the mixture stability and the nature of the sample. It is recommended to perform the

measurement as soon as any photoluminescence or static electricity effects have become negligible, e.g.

after 12 h.

In order to reduce photoluminescence effects, it is recommended that the above mentioned operations take

place in dimmed light (preferably light from an incandescent source or red light); in addition, direct sunlight or

fluorescent light should be avoided.
7.3 Counting procedure

The measurement conditions (measurement time, blank sample, number of cycles or repetitions) will be

defined according to the uncertainty and detection limit to be achieved.
7.3.1 Control and calibration

Statistical control of the detection system shall be monitored by measurement of suitable reference

background and reference sources usually provided by the equipment supplier, for example in compliance

[13]
with ISO 8258 .

The measurement of the blank sample is performed before each analysis or each series of sample

measurement in representative conditions of each type of measurement (Clause 4).

The detection efficiency is determined with a sample of a standard of aqueous tritium (calibration source), or a

dilution of this standard with water for the blank, measured in the same conditions as the test portion.

6 © ISO 2010 – All rights reserved
---------------------- Page: 18 ----------------------
SIST EN ISO 9698:2015
ISO 9698:2010(E)

Using direct measurement, it is essential to generate a quench curve for each type of water measured. The

quench curve is valid only for:
⎯ a given type of measurement equipment;
⎯ a given type of scintillation cocktail;
⎯ a given ratio of scintillation cocktail and test sample.

The quench curve is obtained with a series of working standards (10 for example), presenting different

quench. The matrix of the working standards is representative of matrix of the samples to be measured (same

scintillation liquid, same ratio scintillation liquid-test sample). The working standards may be prepared as

follows:

⎯ similar quantity of certified standard tritiated water solution in each vial; the activity of the certified

standard must be sufficient for the counting ratio to be defined with a known statistical precision, even in

the case of a strong quench;

⎯ the standard is completed with reference water until the volume of test sample is reached;

⎯ the scintillation cocktail is added to obtain the
...

Questions, Comments and Discussion

Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.