Water quality - Determination of the threshold odour number (TON) and threshold flavour number (TFN)

This European Standard specifies quantitative methods for determining the TON and TFN of waters and also a qualitative method for determining any abnormal odour and/or flavour. It is essential that the safety remarks in Clause 5 are taken into account.
Two quantitative methods are described:
   a short method applicable when either a sample has no odour and flavour or when the odour and flavour are to be compared with a specified threshold number;
   a full method applicable when the threshold number for the sample is to be determined.
For both quantitative methods, two different methodologies are described:
   unforced choice in the standard;
   forced choice in Annex B.
Both methods are applicable for quantifying the odour and flavour of drinking water and/or migration waters from materials in contact with waters.
NOTE   The choice of the quantitative or qualitative method is depending on the national regulations, and on the type of water to be assessed (raw water, distribution water, migration water ….)

Wasserbeschaffenheit - Bestimmung des Geruchsschwellenwerts (TON) und des Geschmacksschwellenwerts (TFN)

Diese Europäische Norm legt quantitative Verfahren zur Bestimmung des TON und des TFN in Wasser sowie ein qualitatives Verfahren, das bei ungewöhnlichem Geruch und/oder Geschmack angewendet werden kann, fest. Die Warnhinweise in Abschnitt 5 müssen beachtet  werden.
Zwei quantitative Verfahren werden beschrieben:
-   ein Kurzzeitverfahren, anwendbar, wenn entweder die Probe keinen Geruch oder Geschmack besitzt oder wenn der Geruch und der Geschmack mit einem bestimmten Geruchsschwellenwert verglichen werden soll:
-   ein vollständiges Verfahren, anwendbar, wenn der Schwellenwert der Probe zu ermitteln ist.
Für beide quantitative Verfahren werden verschiedene Vorgehensweisen beschrieben:
-   Verfahren der freien Wahl im Hauptteil der Norm;
-   Verfahren der erzwungenen Wahl im Anhang B.
Beide Verfahren sind anwendbar, um Geruch oder Geschmack von Trinkwasser und/oder von Migrationswasser von Materialien im Kontakt mit Trinkwasser zu bestimmen.
ANMERKUNG   Die Auswahl des qualitativen bzw. der quantitativen Verfahren hängt von den nationalen Festlegungen und von der Art des zu untersuchenden Wassers  (Rohwasser, Leitungswasser, Migrationswasser ...) ab.

Qualité de l'eau - Détermination du seuil d'odeur (TON) et du seuil de flaveur (TFN)

La présente Norme européenne prescrit des méthodes quantitatives de détermination du TON et du TFN des eaux, de meme qu'une méthode qualitative de détermination de toute odeur et/ou flaveur anormales. Il est essentiel que les remarques de sécurité mentionnées a l'article 5 soient prises en compte.
Deux méthodes quantitatives sont décrites :
-   une méthode courte, applicable soit si l’échantillon n’a ni odeur ni flaveur, soit si l’odeur et la flaveur doivent etre comparées a un seuil spécifié ;
-   une méthode complete, applicable lorsque le seuil pour l’échantillon doit etre déterminé.
Deux méthodologies différentes sont décrites pour les deux méthodes quantitatives :
-   le choix non forcé dans la présente norme ;
-   le choix forcé dans l'Annexe B.
Les deux méthodes sont applicables pour quantifier l’odeur et la flaveur de l'eau potable et/ou des eaux de migration provenant des matériaux en contact avec des eaux.
NOTE   Le choix de la méthode quantitative ou qualitative dépend des réglementations nationales et du type d'eau a évaluer (eau non traitée, eau de distribution, eau de migration ).

Kakovost vode - Določanje praga vonja (TON - threshold odour number) in praga okusa (TFN - threshold flavour number)

General Information

Status
Published
Publication Date
31-Jan-2007
Technical Committee
Current Stage
6060 - National Implementation/Publication (Adopted Project)
Start Date
01-Feb-2007
Due Date
01-Feb-2007
Completion Date
01-Feb-2007

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2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.Wasserbeschaffenheit - Bestimmung des Geruchsschwellenwerts (TON) und des Geschmacksschwellenwerts (TFN)Qualité de l'eau - Détermination du seuil d'odeur (TON) et du seuil de flaveur (TFN)Water quality - Determination of the threshold odour number (TON) and threshold flavour number (TFN)13.060.60Preiskava fizikalnih lastnosti vodeExamination of physical properties of waterICS:Ta slovenski standard je istoveten z:EN 1622:2006SIST EN 1622:2007en,fr,de01-februar-2007SIST EN 1622:2007SLOVENSKI
STANDARDSIST EN 1622:19981DGRPHãþD



SIST EN 1622:2007



EUROPEAN STANDARDNORME EUROPÉENNEEUROPÄISCHE NORMEN 1622August 2006ICS 13.060.60Supersedes EN 1622:1997
English VersionWater quality - Determination of the threshold odour number(TON) and threshold flavour number (TFN)Qualité de l'eau - Détermination du seuil d'odeur (TON) etdu seuil de flaveur (TFN)Wasserbeschaffenheit - Bestimmung desGeruchsschwellenwerts (TON) und desGeschmacksschwellenwerts (TFN)This European Standard was approved by CEN on 14 July 2006.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the Central Secretariat or to any CEN member.This European Standard exists in three official versions (English, French, German). A version in any other language made by translationunder the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the officialversions.CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania,Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMITÉ EUROPÉEN DE NORMALISATIONEUROPÄISCHES KOMITEE FÜR NORMUNGManagement Centre: rue de Stassart, 36
B-1050 Brussels© 2006 CENAll rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 1622:2006: ESIST EN 1622:2007



EN 1622:2006 (E) 2 Contents Page Foreword.4 Introduction.5 1 Scope.6 2 Normative references.6 3 Terms and definitions.6 4 Principle.8 5 Hazards.8 6 Test environment.8 7 Apparatus and reagents.8 8 Sampling and sample preservation.9 9 Test panel and selected assessors.9 10 Procedure for unforced choice.10 10.1 General.10 10.2 Type of test.10 10.2.1 The triangle test.10 10.2.2 The paired test.10 10.3 Type of method.10 10.3.1 Short method.10 10.3.2 Full method.11 11 Expression of results.13 11.1 The short method.13 11.2 The full method.13 12 Test report.13 Annex A (normative)
Chlorinated water.15 A.1 General.15 A.2 Dechlorination by addition of sodium thiosulfate.15 A.2.1 Preparation of reagent.15 A.2.2 Procedure.15 A.3 Dechlorination by addition of ascorbic acid.15 A.3.1 Preparation of reagent.15 A.3.2 Procedure.15 Annex B (normative)
Forced choice test method.16 B.1 General.16 B.2 Determination of TON and TFN.16 B.3 Expression of results.17 B.3.1 The short method.17 B.3.2 The full method.17 B.3.3 Test report.17 Annex C (normative)
Qualitative simplified procedure.18 Annex D (informative)
Method for the preparation of reference water).19 D.1 Apparatus and reagents.19 D.2 Procedure.19 Annex E (informative)
Selection of the test panel.20 SIST EN 1622:2007



EN 1622:2006 (E) 3 E.1 General.20 E.2 Self-evaluation.20 E.3 Screening test.20 Annex F (informative)
Preparation of dilutions.23 Annex G (informative)
Interlaboratory test by forced choice methodology.24 Bibliography.27
Figures Figure G.1 — Graphical presentation of threshold flavour number; calculated threshold flavour number is 13,5.25
Tables Table 1 — Threshold numbers.13 Table E.1 — Long term constraints form.21 Table E.2 — Test report form for individual candidates.22 Table F.1 —Examples of successive dilutions, xp (10.3. 2.2).23 Table G.1 — Statistical evaluation by forced choice triangle test (TFN), concerning the measurements obtained by 10 selected assessors, for assessment of drinking water (x=2).24 Table G.2 — Measurements on odour and flavour on geosmin solutions (forced choice, triangle test)25 Table G.3 — Measurements on odour and flavour on geosmin solutions (forced choice, paired test).26
SIST EN 1622:2007



EN 1622:2006 (E) 4 Foreword This document (EN 1622:2006) has been prepared 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 February 2007, and conflicting national standards shall be withdrawn at the latest by February 2007. This document supersedes EN 1622:1997. The forced choice test method has been moved into Annex B. Annex C has been added. The standard has been completely editorially revised. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. SIST EN 1622:2007



EN 1622:2006 (E) 5 Introduction This European Standard gives quantitative methods for the determination of the threshold odour number (TON) and the threshold flavour number (TFN). The main methodology (unforced choice) widely used in Europe is described in this European Standard. Another methodology, used by a limited number of member state (forced choice) is described in Annex B. A simplified qualitative method is also described in Annex C. The methods specified in this European Standard are based on the standard methods for sensory analysis. However, some differences are noted, as compared with those methods, due to water specificity. This European Standard is primarily intended to give a quantitative measure of odour and flavour of a water sample at a temperature of 23 °C. NOTE The method can be used to determine the odour and flavour of a water sample at other temperatures but there will be no correlation between results obtained at different temperatures. WARNING — Persons using this European Standard should be familiar with normal laboratory practice. This European 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 European Standard be carried out by suitably trained staff.
SIST EN 1622:2007



EN 1622:2006 (E) 6 1 Scope This European Standard specifies quantitative methods for determining the TON and TFN of waters and also a qualitative method for determining any abnormal odour and/or flavour. It is essential that the safety remarks in Clause 5 are taken into account. Two quantitative methods are described:  a short method applicable when either a sample has no odour and flavour or when the odour and flavour are to be compared with a specified threshold number;  a full method applicable when the threshold number for the sample is to be determined. For both quantitative methods, two different methodologies are described:  unforced choice in the standard;  forced choice in Annex B. Both methods are applicable for quantifying the odour and flavour of drinking water and/or migration waters from materials in contact with waters. NOTE The choice of the quantitative or qualitative method is depending on the national regulations, and on the type of water to be assessed (raw water, distribution water, migration water ….) 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 7393-2, Water quality — Determination of free chlorine and total chlorine — Part 2: Colorimetric method using N,N-diethyl-1,4-phenylenediamine, for routine control purposes 3 Terms and definitions For the purposes of this European Standard, the following terms and definitions apply. 3.1 odour organoleptic attribute perceptible by the olfactory organ on sniffing certain volatile substances (see ISO 5492) 3.2 flavour complex combination of the olfactory, gustatory and trigeminal sensations perceived during tasting. The flavour may be influenced by tactile, thermal, painful and/or kinaesthetic effects (see ISO 5492) 3.3 threshold odour number (TON) dilution ratio beyond which the diluted sample does not have any perceptible odour ABATON+= (1) where SIST EN 1622:2007



EN 1622:2006 (E) 7 A is the volume of sample; B is the volume of reference water 3.4 threshold flavour number (TFN) dilution ratio beyond which the diluted sample does not have any perceptible flavour ABATFN+= (2) where A is the volume of sample; B is the volume of reference water 3.5 reference water water described as without any perceptible odour and flavour by test panel 3.6 test panel group of selected assessors used to evaluate flavour and odour NOTE For guidance on the selection of the test panel, see Annexes E or G. 3.7 selected assessor assessor chosen for his/her ability to perform a sensory test (see ISO 5492) 3.8 sample water intended for odour and flavour assessment 3.9 triangle test three test samples, two of which are reference water, and the third the sample or a dilution of it, (or two of which are the sample or a dilution of it, and the third one is reference water), are presented to the selected assessors 3.10 paired test two test samples, one is the sample or a dilution of it, and the other is reference water are presented to the selected assessors 3.11 forced choice even if the selected assessor is unable to perceive a difference between the two or three samples, the selected assessor shall chose one sample as having the stronger flavour or odour and record his/her choice 3.12 unforced choice selected assessor recording if he/she notes or does not note a difference between the two or three samples 3.13 migration water test water which has been in contact with a test piece under specified conditions SIST EN 1622:2007



EN 1622:2006 (E) 8 4 Principle The odour and flavour of a water sample are quantitatively assessed by a test panel by comparing that sample and/or dilutions of that sample with a reference water. The odour and flavour of a water sample may also be assessed qualitatively by only one selected assessor or a test panel to detect any abnormal odour and/or flavour. 5 Hazards Care shall be taken to ensure that the samples are safe for selected assessors. If there is any suspicion of the presence of harmful microorganisms or of toxic substances at a toxic concentration, the samples shall not be tested without further precautions being taken. The selected assessors shall be instructed not to swallow any test sample. In case a toxicity risk is suspected, samples should be evaluated for possible risks to the assessors by consideration of previous reports on toxicity tests, made with the sample or samples of similar kind, e.g. by using one of the existing standard methods for aquatic toxicity. In case the risk for presence of human pathogens (bacteria, viruses, parasite eggs) is suspected, it shall be assessed by adequate biological standard methods before conduction of this test. This is not necessary for waters disinfected by chlorinous disinfectants, ozone or UV. 6 Test environment The room used for odour and flavour assessment has to be free from obtrusive draughts and noise and the general environment such that the selected assessors shall perform their task without being influenced by other selected assessors. No air fresheners or room deodorisers shall be used in the room. The room shall be sited away from any activity that could generate interfering odours. The temperature of the room shall be maintained with a system for the regulation of temperature at (23 ± 2) °C. It is advisable that this room is only used for odour and flavour assessment. Suggestions on the design of suitable facilities are given in ISO 8589. 7 Apparatus and reagents 7.1 Glassware, reserved solely for TON and TFN assessment. Glassware shall be cleaned separately from other laboratory items and, when not in use, shall be stored in clean conditions in order to avoid accidental contamination. Sample bottles, tasting glasses and volumetric glassware shall be cleaned before use so that they have no perceptible influence on the result of the assessment. Tasting glasses can be as specified by ISO 3591. NOTE Sample bottles should be of glass and of a suitable capacity. Stoppers should be of glass or polytetrafluoroethene (PTFE) and capable of yielding no headspace in the sample. 7.2 Water bath or incubator, capable of maintaining a homogeneous temperature of (23 ± 2) °C. 7.3 Reference water Reference water (3.5) shall be used for rinsing, dilution and reference. SIST EN 1622:2007



EN 1622:2006 (E) 9 NOTE Reference water can be tap water, mineral bottled water, or prepared according to Annex D. Preferably it should be appropriate to the area and where possible similar in mineral character to the type of water being tested. 7.4 Cleaning liquids; use one of the following cleaning liquids for glassware. 7.4.1 Non-perfumed biodegradable laboratory detergent 7.4.2 Hydrochloric acid, c(HCl) ≈ 2 mol/l. 7.4.3 Hydrogen peroxide, w(H2O2), approximately 3 %. NOTE Other cleaning liquids such as acetic acid can be used before the rinsing procedure of the glassware, provided they yield glassware free from interfering taste and odour. 8 Sampling and sample preservation Collect the samples (with no headspace) in the clean, well stoppered sample bottles (7.1). Keep the samples cool and in the absence of light during transportation and storage. If storage is necessary, store in a refrigerator at (4 ± 2) °C. Storage time shall be as short as possible, in no case longer than 72 h, and be specified with the result. 9 Test panel and selected assessors A test panel shall consist of at least three selected assessors (3.7) for unforced choice (see Clause 10 and eight selected assessors (3.7) for forced choice (see Annex B). For the simplified qualitative method (see Annex C), only one selected assessor may perform the assessment. NOTE 1 When a new test panel is started, the selected assessors will be untrained but will undergo training with flavours and odours to increase their precision. It is accepted that after a period of training and experience, the test panel will become both more selective and more precise than the general population. NOTE 2 Guidance on training the selected assessor is given in Annex E. New selected assessors shall be introduced to the odour and flavour test method by an experienced selected assessor or consultant. Selected assessors shall have gained experience in the method before being integrated into regular test panel sessions. Selected assessors shall be willing to serve, and shall be disqualified if they suffer from allergy or of unusual sensitivity. It is desirable that the sensitivities in a test panel to odour and flavour do not differ widely. The performance of individual selected assessors and test panels shall be monitored. This shall be done by interlaboratory tests depending on the laboratory objectives. NOTE 3 If the laboratory has to determine TON/TFN for approving drinking water materials, the need for interlaboratory test seems obvious. Intra-laboratory exercises on a regular basis may also be carried out with the use of a common spiking tasty or odorous solution. This can be done as a part of interlaboratory quality control of the panellists. This need is not obvious if the laboratory is only checking for the presence/absence of abnormal taste or odour. The precision of the result is dependant on the test panel size. NOTE 4 Even if it is desirable to have a minimum of 5 selected assessors for a paired test and a minimum of 6 for a triangle test, this is not realistic for most water laboratories and utilities. The present standard can be used with a smaller number of panellists for unforced choice, provided the response of the panel is homogenous (see criteria in 10.3.1.4 and in 10.3.2.4). SIST EN 1622:2007



EN 1622:2006 (E) 10 See Annexes E and G for information. 10 Procedure for unforced choice 10.1 General The principle of the method is to quantify the odour and flavour of a sample by the use of a test panel, comparing sample or dilution of it with the reference water. A coordinator organises the activities of the test panel. Before testing, samples of chlorinated water shall be de-chlorinated according to the procedure described in Annex A. 10.2 Type of test 10.2.1 The triangle test Three samples (3.8) two of which are reference water (7.3) and the third the sample or a dilution of it (or two are a sample or a dilution of it and the third is a reference water) are presented simultaneously to the selected assessors. The selected assessors shall select the sample perceived as different. 10.2.2 The paired test Two samples (3.8) one of which is reference water (7.3) and the second the sample or a dilution of it are presented simultaneously to the selected assessors. The selected assessors shall select the sample perceived to have the stronger odour and flavour. 10.3 Type of method 10.3.1 Short method 10.3.1.1 Applicability This short method is applicable when either a sample has no odour and flavour or for compliance of odour and flavour with a specified level. Only one dilution is prepared. 10.3.1.2 Test procedure Prepare a dilution of the water sample to be evaluated using reference water (7.3), according to the threshold of interest. Adjust the temperature of this dilution and one reference water (for paired test) or two reference waters (for triangle test) at (23 ± 2) °C by placing them in a temperature controlled device (7.2). In order to avoid unnecessary quantity of glassware, only one large flask per sample can be used for all selected assessors. An appropriate volume shall be prepared in order that all the selected assessors could have a sufficient volume for the assessment of odour and flavour. NOTE Instead of the preliminary preparation of the dilutions in flasks, intended for comparison with reference water, another equivalent procedure can be applied. The selected assessor(s) can prepare in a measuring cylinder the appropriate dilution just before the odour and flavour assessment. The sample or dilution of it should be compared directly with the reference water. SIST EN 1622:2007



EN 1622:2006 (E) 11 10.3.1.3 Assessment of the sample Each selected assessor shall assess the sample and its dilution by comparing it with reference water (7.3) independently and without knowledge of the results obtained by other selected assessors. Remove the sample, sample dilution and the reference water from the water bath or incubator. For TON assessment, ask each of the selected assessor to shake each flask (and/or measuring cylinder) thoroughly, remove the stopper, smell, replace the stopper and record his/her decision. All the selected assessors will perform the TON assessment on the same flask (and/or measuring cylinder). For TFN assessment, ask each of the selected assessor to transfer a suitable volume of water in his/her own glass, and to hold it in the mouth for several seconds before discharging it without swallowing, before recording his/her decision. If the selected assessor is unable to perceive a difference between the sample or its dilution and the reference water, the selected assessor shall note it. This individual TON or TFN is less than the dilution proposed. NOTE Care should be taken to ensure that the length of the session does not fatigue the selected assessor and cause a lowering of sensitivity. It can be helpful between samples for the selected assessor to eat a water biscuit to recover sensitivity of flavour. The precision of the result is dependant on the size of the test panel and the range of the individual results. 10.3.1.4 Determination of Threshold Number If there is no perceived difference between the sample dilution and the reference water, describe the result as less than the threshold number. There shall be a minimum of three selected assessors contributing a score. If at least 66 % of the selected assessors agree, the test is valid. If not, the test shall be repeated or completed by an additional selected assessor. When necessary, when the result is greater to the specified threshold, the full method (10.3.2) shall be used to quantify the threshold number of the sample. 10.3.2 Full method 10.3.2.1 Applicability The full method is applicable when the threshold number for a sample is to be determined. A series of successive dilutions are prepared and assessed. Make a preliminary evaluation of the threshold number and then prepare a minimum of three dilutions around this expected threshold number with reference water (7.3). If the selected assessor is unable to perceive a sample as different, the last dilution where a difference was perceived represents his/her individual TON or TFN for this sample. 10.3.2.2 Test procedure Prepare a series of clearly labelled dilutions of the sample with reference water (7.3) in the series px where SIST EN 1622:2007



EN 1622:2006 (E) 12 x
is the ratio of the concentration of successive dilutions in the series; p is a series of whole numbers, 0, 1, 2, . i…, indicating the position of each dilution in the test series. The value of x shall be between 1,3 and 3 (see Annex F). NOTE This test procedure gives a dilution series where the concentrations form a geometric progression, i.e. the ratio of the concentrations of each pair of successive dilutions is constant. The use of a geometric series ensures that the change in perceived level of odour or flavour is equal between successive dilutions. Maintain the temperature of all the dilutions and reference water (7.3) in a temperature controlled water bath or incubator (7.2). 10.3.2.3 Assessment of samples Each selected assessor shall assess the samples independently and without knowledge of the results obtained by other selected assessors. Remove the sample or sample dilution and the reference water from the water bath or incubator. For TON assessment, ask each of the selected assessor to shake each flask (or measuring cylinder) thoroughly, remove the stopper, smell, replace the stopper and record his/her decision. All the selected assessors may perform the TON assessment on the same flask. Are more than 4 selected assessors active, the laboratory shall check that the TON of the last group of the assessors is equivalent to the TON of the first group of assessors. For TFN assessment, ask each of the selected assessor to t
...

SLOVENSKI oSIST prEN 1622:2005

PREDSTANDARD
februar 2005
Kakovost vode - Določanje praga/indeksa vonja in praga/indeksa okusa
Water quality - Determination of the threshold odour number (TON) and threshold
flavour number (TFN)
ICS 13.060.20 Referenčna številka
oSIST prEN 1622:2005(en;fr;de)
©  Standard je založil in izdal Slovenski inštitut za standardizacijo. Razmnoževanje ali kopiranje celote ali delov tega dokumenta ni dovoljeno

---------------------- Page: 1 ----------------------
EUROPEAN STANDARD
DRAFT
prEN 1622
NORME EUROPÉENNE

EUROPÄISCHE NORM

December 2004
ICS Will supersede EN 1622:1997
English version
Water quality - Determination of the threshold odour number
(TON) and threshold flavour number (TFN)
Qualité de l'eau - Détermination du seuil d'odeur (TON) et Wasserbeschaffenheit - Bestimmung des
du seuil de flaveur (TFN) Geruchsschwellenwerts (TON) und des
Geschmacksschwellenwerts (TFN)
This draft European Standard is submitted to CEN members for enquiry. It has been drawn up by the Technical Committee CEN/TC 230.

If this draft becomes a European Standard, 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.

This draft European Standard was established by CEN 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 Management Centre has the same
status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,
Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia,
Slovenia, Spain, Sweden, Switzerland and United Kingdom.

Warning : This document is not a European Standard. It is distributed for review and comments. It is subject to change without notice and
shall not be referred to as a European Standard.


EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

Management Centre: rue de Stassart, 36  B-1050 Brussels
© 2004 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN 1622:2004: E
worldwide for CEN national Members.

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prEN 1622:2004 (E)
Contents Page
Foreword.3
Introduction .4
1 Scope .5
2 Normative references .5
3 Terms and definitions .5
4 Principle.7
5 Hazards .7
6 Test environment.7
7 Apparatus and reagents.7
8 Sampling and sample preservation .8
9 Test panel and selected assessors.8
10 Procedure for unforced choice .9
11 Expression of results .12
12 Test report .13
Annex A (normative) Chlorinated water .14
Annex B (normative) Forced choice test method.15
Annex C (normative) Qualitative simplified procedure.17
Annex D (informative) Method for the preparation of reference water .18
Annex E (informative) Selection of the test panel.19
Annex F (informative) Preparation of dilutions .22
Annex G (informative) Example of forced choiced methodology - Interlaboratory tests .23
2

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prEN 1622:2004 (E)
Foreword
This document (prEN 1622) has been prepared by Technical Committee CEN/TC 230 “Water analysis”, the
secretariat of which is held by DIN.
This document is currently submitted to the CEN Enquiry.
This document will supersede EN 1622:1997.

3

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prEN 1622:2004 (E)
Introduction
This European Standard gives quantitative methods for the determination of the threshold odour number
(TON) and the threshold flavour number (TFN). The main methodology (unforced choice) widely used in
Europe is described in the standard.
Another methodology, used by a limited number of member state (forced choice) is described in Annex B.
A simplified qualitative method, is also described in Annex C.
The methods specified in this European Standard are based on the standard methods for sensory analysis.
However, some differences are noted, as compared with those methods, due to water specificity.
This European Standard is primarily intended to give a quantitative measure of odour and flavour of a water
sample at a temperature of 25 °C.
NOTE The method can be used to determine the odour and flavour of a water sample at other temperatures but
there will be no correlation between results obtained at different temperatures.
WARNING — Persons using this European Standard should be familiar with normal laboratory
practice. This 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 European Standard be
carried out by suitably trained staff.
4

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prEN 1622:2004 (E)

1 Scope
This European Standard specifies quantitative methods for determining the TON and TFN of waters and also
a qualitative method for determining any abnormal odour and/or flavour. It is essential that the safety remarks
in Clause 5 are taken into account.
Two quantitative methods are described:
 a short method applicable when either a sample has no odour and flavour or when the odour and flavour
are to be compared with a specified threshold number;
 a full method applicable when the threshold number for the sample is to be determined.
For both quantitative methods, two different methodologies are described:
 unforced choice in the standard,
 forced choice in Annex B.
Both methods are applicable for quantifying the odour and flavour of drinking water and/or migration waters
from materials in contact with waters.
NOTE The choice of the quantitative or qualitative method is depending on the national regulations, and on the type
of water to be assessed ( raw water, distribution water, migration water ….)
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 3591, Sensory analysis — Apparatus — Wine-tasting glass.
ISO 5492, Sensory analysis — Vocabulary.
ISO 8589, Sensory Analysis — General guidance for the design of test rooms.
ISO 7393-2, Water quality — Determination of free chlorine and total chlorine — Part 2: Colorimetric method
using N,N-diethyl-1,4-phenylenediamine, for routine control purposes.
3 Terms and definitions
For the purposes of this European Standard, the following terms and definitions apply.
3.1
odour
organoleptic attribute perceptible by the olfactory organ on sniffing certain volatile substances (see ISO 5492)
3.2
flavour
complex combination of the olfactory, gustatory and trigeminal sensations perceived during tasting. The
flavour may be influenced by tactile, thermal, painful and/or kinaesthetic effects (see ISO 5492)
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3.3
threshold odour number (TON)
dilution ratio beyond which the diluted sample does not have any perceptible odour
A + B
TON = (1)
A
where
A is the volume of sample;
B is the volume of reference water.
3.4
threshold flavour number (TFN)
dilution ratio beyond which the diluted sample does not have any perceptible flavour
A + B
TFN = (2)
A
where
A is the volume of sample;
B is the volume of reference water.
3.5
reference water
the water described as without any perceptible odour and flavour by individual selected assessor
3.6
test panel
a group of selected assessors used to evaluate flavour and odour
NOTE For guidance on the selection of the test panel, see Annexes E or G.
3.7
selected assessor
assessor chosen for his/her ability to perform a sensory test (see ISO 5492)
3.8
sample
water intended for odour and flavour assessment
3.9
triangle test
three test samples, two of which are reference water, and the third the sample or a dilution of it
3.10
paired test
two test samples, one is the sample or a dilution of it, and the other is reference water
3.11
forced choice
even if the selected assessor is unable to perceive a difference between the two or three samples, the
selected assessor shall chose one sample as having the greater flavour or odour and record his/her choice
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3.12
unforced choice
the selected assessor shall record if he/she notes or does not note a difference between the two or three
samples
4 Principle
The odour and flavour of a water sample are quantitatively assessed by a test panel by comparing that
sample and/or dilutions of that sample with a reference water.
The odour and flavour of a water sample may also be assessed qualitatively by only one selected assessor or
a test panel to detect any abnormal odour and/or flavour.
5 Hazards
Care shall be taken to ensure that the samples are safe for selected assessors. If there is any suspicion of the
presence of harmful microorganisms or of toxic substances at a toxic concentration, the samples shall not be
tested without further precautions being taken.
Depending on the type of sample being tested, the selected assessors shall be instructed not to swallow any
test sample.
6 Test environment
The room used for odour and flavour assessment has to be free from obtrusive draughts and noise and the
general environment such that the selected assessors shall perform their task without being influenced by
other selected assessors.
No air fresheners or room deodorisers shall be used in the room. The room shall be sited away from any
activity that could generate interfering odours. The temperature of the room shall be maintained with a system
for the regulation of temperature at (23 ± 2) °C. It is advisable that this room is only used for odour and flavour
assessment. Suggestions on the design of suitable facilities are given in ISO 8589.
7 Apparatus and reagents
7.1 Glassware, reserved solely for TON and TFN assessment.
Glassware shall be cleaned separately from other laboratory items and, when not in use, shall be stored in
clean conditions in order to avoid accidental contamination.
Sample bottles, tasting glasses and volumetric glassware shall be cleaned before use so that they have no
perceptible influence on the result of the assessment.
Tasting glasses can be as specified by ISO 3591.
NOTE Sample bottles should be of glass and of a suitable capacity. Stoppers should be of glass or
polytetrafluoroethene (PTFE) and capable of yielding no headspace in the sample.
7.2 Water bath or incubator, capable of maintaining an homogeneous temperature of (23 ± 2) °C.
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7.3 Reference water
Odour and flavour free water used for rinsing, dilution and reference, preferably appropriate to the area and
where possible similar in mineral character to the type of water being tested.
NOTE Reference water can be tap water, mineral bottled water, or prepared according to Annex D.
7.4 Cleaning liquids; use one of the following cleaning liquids for glassware.
7.4.1 Non-perfumed biodegradable laboratory detergent
7.4.2 Hydrochloric acid, c(HCl) ≈ 2 mol/l.
7.4.3 Hydrogen peroxide, w(H O ), approximately 3 %.
2 2
NOTE Other cleaning liquids such as acetic acid can be used before the rinsing procedure of the glassware, provided
they yield glassware free from interfering taste and odour.
8 Sampling and sample preservation
Collect the samples (with no headspace) in the clean, well stoppered sample bottles (7.1). Keep the samples
cool and in the absence of light during transportation and storage. If storage is necessary, store in a
refrigerator at (4 ± 2) °C. Storage time shall be as short as possible, in no case longer than 72 h, and be
specified with the result.
9 Test panel and selected assessors
A test panel shall consist of at least three selected assessors (3.7) for unforced choice (see Clause 10 and
eight selected assessors (3.7) for forced choice (see Annex B).
For the simplified qualitative method (see Annex C), only one selected assessor may perform the assessment.
NOTE 1 When a new test panel is started, the selected assessors will be untrained but will undergo training with
flavours and odours to increase their precision. It is accepted that after a period of training and experience, the test panel
will become both more selective and more precise than the general population.
NOTE 2 Guidance on training the selected assessor is given in Annex E.
New selected assessors shall be introduced to the odour and flavour test method by an experienced selected
assessor or consultant. Selected assessors shall have gained experience in the method before being
integrated into regular test panel sessions.
Selected assessors shall be willing to serve, and shall be disqualified if they suffer from allergy or of unusual
sensitivity. It is desirable that the sensitivities in a test panel to odour and flavour do not differ widely.
The performance of individual selected assessors and test panels shall be monitored. This shall be done by
interlaboratory tests depending on the laboratory objectives.
NOTE 3 If the laboratory has to determine TON/TFN for approving drinking water materials, the need for interlaboratory
test seems obvious. Intralaboratory exercises on a regular basis may also be carried out with the use of a common spiking
tasty or odorous solution. This can be done as a part of interlaboratory quality control of the panellists.
This need is not obvious if the laboratory is only checking for the presence/absence of abnormal taste or
odour.
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The precision of the result is dependant on the test panel size.
See Annexes E and G for information.
10 Procedure for unforced choice
10.1 General
The principle of the method is to quantify the odour and flavour of a sample by the use of a test panel,
comparing sample or dilution of it with the reference water. A coordinator organises the activities of the test
panel.
Before testing, samples of chlorinated water shall be dechlorinated according to the procedure described in
Annex A.
10.2 Type of test
10.2.1 The triangle test
Three samples (3.8 ) two of which are reference water (7.3) and the third the sample or a dilution of it are
presented simultaneously to the selected assessors. The selected assessors shall select the sample
perceived as different.
10.2.2 The paired test
Two samples (3.8 ) one of which is reference water (7.3) and the second the sample or a dilution of it are
presented simultaneously to the selected assessors. The selected assessors shall select the sample
perceived to have the greater odour and flavour.
10.3 Type of method
10.3.1 Short method
10.3.1.1 Applicability
This short method is applicable when either a sample has no odour and flavour or for compliance of odour and
flavour with a specified level. Only one dilution is prepared.
10.3.1.2 Test procedure
Prepare a dilution of the water to be evaluated using reference water (7.3), according to the threshold of
interest. Adjust the temperature of this dilution and one reference water (for paired test) or two reference
waters (for triangle test) at (23 ± 2) °C by placing them in a temperature controlled device (7.2).
Alternatively, in order to avoid unnecessary quantity of glassware, only one large flask per sample can be
used for all the selected assessors, instead of a set of flasks and glasses per selected assessor, sample
dilution and reference water.
An appropriate volume shall be prepared in order that all the selected assessors could have a sufficient
volume for the assessment of odour and flavour.
NOTE Instead of the preliminary preparation of the dilutions in flasks, intended for comparison with reference water,
another equivalent procedure can be applied. The selected assessor(s) can prepare in a measuring cylinder the
successive appropriate dilutions just before the odour and flavour assessment. The sample or dilution of it should be
compared directly with the reference water.
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10.3.1.3 Assessment of samples
Each selected assessor shall assess the samples by comparing them with reference water (7.3)
independently and without knowledge of the results obtained by other selected assessors.
Remove the sample or sample dilution and the reference water from the water bath or incubator.
For TON assessment, ask each of the selected assessor to shake each flask (and/or measuring cylinder)
thoroughly, remove the stopper, smell, replace the stopper and record his/her decision.
All the selected assessors will perform the TON assessment on the same flask (and/or measuring cylinder).
For TFN assessment, ask each of the selected assessor to transfer a suitable volume of water in his/her own
glass, and to hold it in the mouth for several seconds before discharging it without swallowing, before
recording his/her decision.
If the selected assessor is unable to perceive one of the samples or a dilution of it as different, the selected
assessor shall note it. This individual TON or TFN is less than the dilution proposed.
NOTE Care should be taken to ensure that the length of the session does not fatigue the selected assessor and
cause a lowering of sensitivity. It can be helpful between samples for the selected assessor to eat a water biscuit to
recover sensitivity of flavour.
The precision of the result is dependant on the size of the test panel, the range of the individual results, the
range of the dilutions chosen.
10.3.1.4 Evaluation
If there is no perceived difference between the sample and the reference water at this dilution, describe the
result as less than the threshold number. There shall be a minimum of three selected assessors contributing a
score.
If at least 67 % of the selected assessors agree, the test is valid
 if the required level of agr
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