1、June 2014 Translation by DIN-Sprachendienst.English price group 14No part of this translation may be reproduced without prior permission ofDIN Deutsches Institut fr Normung e. V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany,has the exclusive right of sale for German Standards (DIN-Normen).ICS 0
2、7.100.20!%2c,“2156409www.din.deDDIN EN ISO 17994Water quality Requirements for the comparison of the relative recovery ofmicroorganisms by two quantitative methods (ISO 17994:2014);English version EN ISO 17994:2014,English translation of DIN EN ISO 17994:2014-06Wasserbeschaffenheit Anforderungen fr
3、den Vergleich der relativen Wiederfindung von Mikroorganismen durchzwei quantitative Verfahren (ISO 17994:2014);Englische Fassung EN ISO 17994:2014,Englische bersetzung von DIN EN ISO 17994:2014-06Qualit de leau Exigences pour la comparaison du rendement relatif des microorganismes par deuxmthodes q
4、uantitatives (ISO 17994:2014);Version anglaise EN ISO 17994:2014,Traduction anglaise de DIN EN ISO 17994:2014-06SupersedesDIN EN ISO 17994:2004-09www.beuth.deIn case of doubt, the German-language original shall be considered authoritative.Document comprises 30 pages05.14 DIN EN ISO 17994:2014-06 2 A
5、 comma is used as the decimal marker. National foreword This document (EN ISO 17994:2014) has been prepared by Technical Committee ISO/TC 147 “Water quality” in collaboration with Technical Committee CEN/TC 230 “Water analysis” (Secretariat: DIN, Germany). The responsible German body involved in its
6、 preparation was the Normenausschuss Wasserwesen (Water Practice Standards Committee), Working Committee NA 119-01-03-03-01 AK Vergleichbarkeit mikrobiolo-gischer Nachweisverfahren of NA 119-01-03 AA Wasseruntersuchung. Designation of the method: Requirements for the comparison of the relative recov
7、ery of microorganisms by two quantitative methods (K 4): Method DIN EN ISO 17994 K 4 The DIN Standards corresponding to the International Standards referred to in this document are as follows: ISO 8199 DIN EN ISO 8199 ISO/TR 13843 DIN V ENV ISO 13843 Expert assistance and specialized laboratories wi
8、ll be required to perform the analyses described in this standard. Existing safety requirements are to be observed. Depending on the objective of the analysis, a check shall be made on a case-by-case basis as to whether and to what extent additional conditions will have to be specified. This standar
9、d has been prepared by the Normenausschuss Wasserwesen (Water Practice Standards Committee) in collaboration with the Wasserchemische Gesellschaft Fachgruppe in der Gesellschaft Deutscher Chemiker (Water Chemistry Society Division of the German Chemical Society). It is part of the series Deutsche Ei
10、nheitsverfahren zur Wasser-, Abwasser- und Schlammuntersuchung (German standard methods for the examination of water, waste water and sludge): Requirements for the comparison of the relative recovery of microorganisms by two quantitative methods (K 4). Standard methods published as DIN Standards are
11、 obtainable from Beuth Verlag GmbH, either individually or grouped in volumes. The standard methods included in the loose-leaf publication entitled Deutsche Einheitsverfahren zur Wasser-, Abwasser- und Schlammuntersuchung will continue to be published by Wiley-VCH Verlag GmbH b) examples and notes h
12、ave been included to make procedures and requirements more comprehensible; c) Clause 1 “Scope” has been rendered more precise and defines the limits of the procedure; d) qualitative methods have been deleted; e) Clause 2 “Normative references” has been supplemented to include ISO 8199; f) Clause 3 “
13、Terms, definitions and symbols” has been revised; g) requirements for the types of samples have been rendered more precise (Subclause 5.3); h) requirements for the number of participating laboratories have been included (Subclause 5.4.1); i) requirements for the number of samples required have been
14、revised (Subclause 5.4.2); j) Clause 6 “Calculations” has been revised; k) evaluation criteria for comparison tests have been revised (Clause 7); l) Annex C (informative) “Derivation of equation for calculation of the number of samples” has been added; m) Annex D “Example of a two-sided evaluation”
15、has been revised; n) the standard has been editorially revised. Previous editions DIN EN ISO 17994: 2004-09 DIN EN ISO 17994:2014-06 4 National Annex NA (informative) Bibliography DIN EN ISO 8199, Water quality General guidance on the enumeration of microorganisms by culture DIN V ENV ISO 13843, Wat
16、er quality Guidance on validation of microbiological methods EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 17994 February 2014 ICS 07.100.20; 13.060.70 Supersedes EN ISO 17994:2004English Version Water quality - Requirements for the comparison of the relative recovery of microorganisms by
17、 two quantitative methods(ISO 17994:2014)Qualit de leau - Exigences pour la comparaison du rendement relatif des microorganismes par deux mthodes quantitatives (ISO 17994:2014) Wasserbeschaffenheit - Anforderungen fr den Vergleich der relativen Wiederfindung von Mikroorganismen durch zwei quantitati
18、ve Verfahren (ISO 17994:2014) This European Standard was approved by CEN on 8 February 2014. 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
19、 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 u
20、nder 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, Forme
21、r 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. CEN-CENELEC Management Centre: Avenue Marnix 1
22、7, B-1000 Brussels 2014 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN ISO 17994:2014 EEUROPEAN COMMITTEE FOR STANDARDIZATIONCOMIT EUROPEN DE NORMALISATIONEUROPISCHES KOMITEE FR NORMUNGContents Page Foreword . 3 Introduction . 4 1
23、 Scope . 5 2 Normative references. 5 3 Terms, definitions and symbols . 5 3.1 Terms and definitions 5 3.2 Symbols and abbreviated terms . 7 4 Principle 7 5 Basic requirements for a comparison study . 8 5.1 General 8 5.2 Description of methods . 8 5.3 Types of samples . 8 5.4 Number of samples and pa
24、rticipating laboratories 9 5.5 Counting and confirming 11 6 Calculations 12 6.1 Preliminary editing of the raw data 12 6.2 Basic relative differences 12 6.3 Half-width of the confidence interval . 13 7 Evaluation . 13 7.1 Preliminary evaluations . 13 7.2 Two-sided evaluation . 14 7.3 One-sided evalu
25、ation . 16 8 Test report . 17 Annex A (informative) Flowchart 18 Annex B (informative) Comparison studies 19 Annex C (informative) Derivation of equation for calculation of the number of samples 21 Annex D (informative) Example of a two-sided evaluation 23 Bibliography 26 DIN EN ISO 17994:2014-06EN
26、ISO 17994:2014 (E) 2Foreword This document (EN ISO 17994:2014) has been prepared by Technical Committee ISO/TC 147 Water quality in collaboration with 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 nation
27、al standard, either by publication of an identical text or by endorsement, at the latest by August 2014, and conflicting national standards shall be withdrawn at the latest by August 2014. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent r
28、ights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. This document supersedes EN ISO 17994:2004. According to the CEN-CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European S
29、tandard: 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,
30、 Spain, Sweden, Switzerland, Turkey and the United Kingdom. Endorsement notice The text of ISO 17994:2014 has been approved by CEN as EN ISO 17994:2014 without any modification. “ ”3DIN EN ISO 17994:2014-06EN ISO 17994:2014 (E)IntroductionThis International Standard specifies criteria and procedures
31、 for comparing the average quantitative results obtained by two microbiological analytical methods, one of which may, but need not, be a standard or reference method.The methods considered are based on counts of colonies or of positive and negative liquid enrichment tubes (MPN).4DIN EN ISO 17994:201
32、4-06EN ISO 17994:2014 (E) 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 pra
33、ctices and to ensure compliance with any national regulatory conditions.IMPORTANT It is absolutely essential that tests conducted in accordance with this document be carried out by suitably qualified staff.1 ScopeThis International Standard specifies an evaluation procedure for comparing two methods
34、 with established performance characteristics according to ISO/TR 13843 and intended for the quantification of the same target group or species of microorganisms.This International Standard provides the mathematical basis for the evaluation of the average relative performance of two quantitative met
35、hods against chosen criteria for the comparison. It does not provide data for assessment of the precision of the methods being compared. It is appropriate that the precision of methods is assessed as part of their performance characterization.This International Standard does not provide methods for
36、the verification of method performance characterization in a single laboratory.2 Normative referencesThe following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated
37、references, the latest edition of the referenced document (including any amendments) applies.ISO 8199, Water quality General guidance on the enumeration of micro-organisms by cultureISO/TR 13843, Water quality Guidance on validation of microbiological methods3 Terms, definitions and symbols3.1 Terms
38、 and definitionsFor the purposes of this document, the following terms and definitions apply.3.1.1 General terms3.1.1.1comparison trialinterlaboratory method comparison that involves laboratories which perform paired measurements on several of their own samples with two different methods5DIN EN ISO
39、17994:2014-06EN ISO 17994:2014 (E)3.1.1.2not-different methodmethod considered quantitatively not different to another method when the mean difference between their confirmed counts and stipulated difference lie between predetermined stipulated limits, taking into account all sources of variationNot
40、e 1 to entry: This difference can be assessed by the average relative difference of their confirmed counts.3.1.1.3predetermined stipulated limitpermitted average difference (based on a “confidence interval” designated 2L to +2L) between results obtained by each method, based on professional practice
41、s or regulatory requirementsNote 1 to entry: Reference 1 suggests that, in international and interlaboratory method performance tests, a limit of 2L = 10 % for setting the “confidence interval” be the predetermined stipulated limit for drinking water, and this has been widely used. However, for envi
42、ronmental waters, such as bathing waters, Reference 2 proposes a predetermined stipulated limit of 2L = 20 %.3.1.1.4reference methodmethod of analysis internationally recognized by experts or by agreement between the partiesNote 1 to entry: As a rule, the reference method is a standard or a commonly
43、 used method.3.1.1.5standard measurement uncertaintymeasurement uncertainty expressed as a standard deviationSOURCE: ISO/IEC Guide 99:2007 (3), 2.303.1.1.6trial methodany method which is to be tested for comparison with a reference method3.1.2 Specific terms3.1.2.1countobserved number of objectsEXAM
44、PLE Colonies or cells of microorganisms, plaques of bacteriophagesNote 1 to entry: In this International Standard, the result of an MPN estimation is also considered to be a count.3.1.2.2presumptive countcolony count or most probable number (MPN) estimate based on the number of colonies or fermentat
45、ion tubes that have an outward appearance that is interpreted as typical of a target organism3.1.2.3confirmed countpresumptive count multiplied by the confirmation coefficient3.1.2.4relative differenceRDdifference between two results, a and b, measured on a relative (natural logarithmic) scale6DIN E
46、N ISO 17994:2014-06EN ISO 17994:2014 (E) 3.2 Symbols and abbreviated termsA (symbol for the idea of) trial methoda test result by method Aaitest result (confirmed count) of method A in sample iB (symbol for the idea of) reference methodb test result by method Bbitest result (confirmed count) of meth
47、od B in sample ii subscript indicating a seriesk coverage factor used for calculating the confidence intervalL smallest microbiologically significant mean relative difference between the results by methods A and BMPN most probable number quantitative methodn number of sampless experimental standard
48、deviation of the relative difference (standard uncertainty)s2experimental variancesxstandard deviation of the relative difference (standard uncertainty) of the meanW half-width of the confidence intervalx relative differencexivalue of the relative difference between aiand biin sample ixarithmetic me
49、an of xi(i = 1,2 n)xLvalue of the relative difference at the lower confidence limit, derived by subtracting the value of the half-width of the confidence interval from the meanxUvalue of the relative difference at the upper confidence limit, derived by adding the value of the half-width of the confidence interval to the meanX2experimental Poisson index of dispersiony conditional variable used in computing the number of samples for comparison testing4 PrincipleT
