DIN EN ISO 10523-2012 Water quality - Determination of pH (ISO 10523 2008) German version EN ISO 10523 2012《水质 PH值的测定(ISO 10523-2008) 德文版本EN ISO 10523-2012》.pdf

1、April 2012 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

2、13.060.50!$?“1885828www.din.deDDIN EN ISO 10523Water quality Determination of pH (ISO 10523:2008)English translation of DIN EN ISO 10523:2012-04Wasserbeschaffenheit Bestimmung des pH-Werts (ISO 10523:2008)Englische bersetzung von DIN EN ISO 10523:2012-04Qualit de leau Dtermination du pH (ISO 10523:2

3、008)Traduction anglaise de DIN EN ISO 10523:2012-04SupersedesDIN 38404-5:2009-07www.beuth.deDocument comprises pagesIn case of doubt, the German-language original shall be considered authoritative.2906.12 DIN EN ISO 10523:2012-04 2 A comma is used as the decimal marker. National foreword This standa

4、rd has been prepared by Technical Committee ISO/TC 147 “Water quality” and has been taken over as EN ISO 10523:2012 by Technical Committee CEN/TC 230 “Water analysis” (Secretariat: DIN, Germany). The responsible German body involved in its preparation was the Normenausschuss Wasserwesen (Water Pract

5、ice Standards Committee), Working Committee NA 119-01-03 AA Wasseruntersuchung, Working Group NA 119-01-03-01-17 AK pH-Wert. This standard is part of the series Deutsche Einheitsverfahren zur Wasser-, Abwasser- und Schlamm-untersuchung Anionen (Gruppe D) (German standard methods for the examination

6、of water, waste water and sludge Anions (group D) and describes method C 5. Designation of the method: “Determination of pH (C 5)”: Method DIN EN ISO 10523 C 5 This standard has been published to implement the Water Framework Directive (WFD), Directive 2000/60/EC of the European Parliament and of th

7、e Council of 23 October 2000 establishing a framework for Community action in the field of water policy.1)ATTENTION If the pH value is required for further water-chemical calculations (e.g. for determining the calcit saturation of water in accordance with DIN 38404-10), reporting to two decimal plac

8、es may results are to be taken (e.g. multiple determinations) and explained in the analysis report. The DIN Standards corresponding to the International Standards referred to in this document are as follows: ISO 3696 DIN ISO 3696 ISO 4796-2 DIN EN ISO 4796-2 ISO 5667-3 DIN EN ISO 5667-3 Expert assis

9、tance and specialized laboratories will be required to perform the analysis described in this standard. Existing safety regulations are to be taken into account. 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 cond

10、itions will have to be specified. Standard methods published as DIN Standards are 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 Schlammuntersuchu

11、ng will continue to be published jointly by Wiley-VCH Verlag and Beuth Verlag GmbH. All standard methods relevant to the Abwasserverordnung (Waste Water Regulation) (AbwV1) included in the new Regulation on Section 57, paragraph 1, number 1, of the Gesetz zur Ordnung des Wasserhaushaltes (German Wat

12、er Management Act1) concerning Anforderungen an das Einleiten von Abwasser in Gewsser together with the Abwasserverordnung and the Gesetz zur Ordnung des Wasserhaushalts have been 1) Registered in the DITR database of DIN Software GmbH, obtainable from: Beuth Verlag GmbH, 10772 Berlin. be appropriat

13、e. In such cases, additional measures for assuring the quality (i.e. reliability) of the German standard methods for the examination of water, waste water and sludge DIN EN ISO 10523:2012-04 3 Standards or draft standards bearing the group title “German standard methods for the examination of water,

14、 waste water and sludge” are classified under the following categories (main titles): General information (group A) (DIN 38402) Sensory analysis (group B) (DIN 38403) Physical and physicochemical parameters (group C) (DIN 38404) Anions (group D) (DIN 38405) Cations (group E) (DIN 38406) Substance gr

15、oup analysis (group F) (DIN 38407) Gaseous constituents (group G) (DIN 38408) Parameters characterizing effects and substances (group H) (DIN 38409) Biological-ecological methods of analysis (group M) (DIN 38410) Microbiological methods (group K) (DIN 38411) Test methods using water organisms (group

16、 L) (DIN 38412) Individual constituents (group P) (DIN 38413) Sludge and sediments (group S) (DIN 38414) Bio-assays with microorganisms (group T) (DIN 38415) In addition to the methods described in the DIN 38402 to DIN 38415 series of standards, there are a number of European and International Stand

17、ards available as DIN EN, DIN EN ISO and DIN ISO Standards, which also form part of the collection of German standard methods. Information on Parts of these series of standards that have already been published can be obtained from the offices of the Normenausschuss Wasserwesen, telephone +49 30 2601

18、2448, or from Beuth Verlag GmbH, Burggrafenstr. 6, 10787 Berlin. Amendments This standard differs from DIN 38404-5:2009-07 as follows: a) number and title of the standard have been changed; b) Annex E of DIN 38404-5:2009-07 has been included as an informative national annex; c) the standard has bee

19、n editorially revised. Previous editions DIN 38404-5: 1984-01, 2009-07 published by Beuth Verlag GmbH as a loose-leaf collection Analysenverfahren in der Abwasserverordnung Rechtsvorschriften und Normen (Supplements). DIN EN ISO 10523:2012-04 4 National Annex NA (informative) Calculating the measure

20、ment uncertainty of a pH value NA.1 Measurement uncertainty The factors that influence the uncertainty of a pH measurement are shown in the cause-and-effect diagram below (see Figure NA.1). Key pH(S) pH values of the buffer solutions used to calibrate pH meters S pH(X) pH value of the measuring solu

21、tion X E(S) electrode voltage for the buffer solutions S E(X) electrode voltage for the measuring solution X Figure NA.1 Cause-and-effect diagram for pH measurement A mathematical procedure for combining individual contributions to uncertainty is described in 2 and 4. This National Annex gives an ex

22、ample of the calculation of the uncertainty of a pH measurement. NA.2 Determining the pH value by means of two-point calibration Calculate the pH value of the measuring solution, pH(X), and the practical slope k using Equations (NA.2) to (NA.3). (S1)(S2)(S1)(X)pH(S1) pH(S2)pH(S1)pH(X)EEEE(NA.1) pH(S

23、1)pH(S2)(S1)(S2)EEk(NA.2) DIN EN ISO 10523:2012-04 5 Solve Equation (NA.1) for pH(X). (S1)(S2)(S1)(X)pH(S1)pH(S2)pH(S1)pH(X)EEEE(NA.3) where pH(S1) is the pH value of buffer solution S1; pH(S2) is pH value of buffer solution S2; E(X) is the electrode voltage in measuring solution X; E(S1) is the ele

24、ctrode voltage in S1; E(S2) is the electrode voltage in S2. Estimate the standard uncertainty for each source of uncertainty 10, 11, 12. Calculate the square of the combined standard uncertainty uc(pH(X), Equation (NA.4), by multiplying the standard uncertainties uiby the sensitivity coefficients (p

25、artial derivatives with respect to the input quantities) ci, Equations (NA.5) to (NA.9) 2. 22222(pH(S2)(pH(S2)(pH(S1)(pH(S1)pH(X)( ucucuc 222222)X(X)()2S(S2)()1S(S1)( EuEcEuEcEuEc (NA.4) NA.3 Sensitivity coefficients The sensitivity coefficient cidescribes the extent to which the result is dependent

26、 on the value of the relevant input quantity. (S1)(S2)(S1)(X)1pH(S1)pH(X)(pH(S1)EEEEc(NA.5) (S1)(S2)(S1)(X)pH(S2)pH(X)(pH(S2)EEEEc(NA.6) 2(S1)(S2)(S1)(X)pH(S1)pH(S2)(S1)(S2)pH(S1)pH(S2)S1)(pH(X)(S1)(EEEEEEEEc(NA.7) 2(S1)(S2)(S1)(X)pH(S1)pH(S2)S2)(pH(X)(S2)(EEEEEEc(NA.8) (S1)(S2)pH(S1)pH(S2)(X)(pH(X)

27、X)(EEEEc(NA.9) DIN EN ISO 10523:2012-04 6 NA.4 Example A manually adjusted pH meter was used to measure the pH value. The pH electrode and pH meter were calibrated and adjusted in accordance with 9.2. The certified buffers S1 and S2 were used for calibration, the standard uncertainty of the buffers

28、 was u(xi) 0,01. The measurement temperature was 24,5 C. The expected range of pH values for a waste water sample was 6,5 to 7,5. Measuring equipment Resolution of pH value reading 0,01 Resolution of voltage reading 1 mV Resolution of temperature measurement 0,1 K Stability criterion 0,05 pH/min Ele

29、ctrode combination electrode with ceramic diaphragm Measurement values Calibration pH(S1) 4,01 E(S1) 175 mV (voltage measured for buffer S1) pH(S2) 6,87 E(S2) 7 mV (voltage measured for buffer S2) Measurement E(X) 52 mV (waste water sample) The practical slope k and pH value for the sample pH(X) are

30、 calculated using Equations (NA.2) and (NA.3). The measured data give the following values: k 58,7 mV and pH(X) 6,1 The certificates for the buffer solutions and the pH meter used, as well as the repeatability of the measurements, result in the standard uncertainties summarized in Table NA.1. The se

31、nsitivity coefficients are calculated using Equations (NA.5) to (NA.9). From this it follows that the pH value of the waste water sample under investigation is pH(X) 6,1 0,1. DIN EN ISO 10523:2012-04 7 Table NA.1 Standard uncertainties Quantity Value Standard uncertainty Sensitivity coefficient Unce

32、rtainty contribution Uncertainty contribution xiu(xi) ciui(y)2 u(xi)2 2ic ui(y) % pH(S1) 4,01 0,01 0,268 7,17 1060,4 pH(S2) 6,87 0,01 0,73 5,36 1052,8 E(S1) 175 mV 2 mV 0,004 61/mV 8,30 1054,3 E(S2) 7 mV 2 mV 0,013 1/mV 6,20 10432,3 E(X) 52 mV 2 mV 0,017 1/mV 1,16 10360,2 Measured value pH(X) 6,10 T

33、otal 1,90 103100 Combined standard uncertainty uc(y) ui(y)21/20,045 Expanded uncertainty U(pH(X) 2 uc(y) 0,1 NA.5 Determining the pH value by means of multi-point calibration 7, 8 Calibration is carried out using at least three, and usually five buffer solutions which cover the range of pH values fo

34、r the unknown solutions. Multi-point calibration is used to determine the practical slope of the electrode, and to test the quality of the reference buffer solutions and the general condition of the electrode. Determine the practical slope and the zero point of the electrode, as well as the associat

35、ed uncertainty, from the slope and the -intercept . Multi-point calibration is used for pH measurement when a high level of accuracy can be achieved, e.g. in well-defined laboratory systems or for well-characterized water. The following text presents the necessary mathematical equations and explains

36、 their use. Calculate the reference line with a slope and y-intercept and their associated uncertainties sand s, respectively, using Equations (NA.10) to (NA.13): iiiiiiiiniEiiiEi222)()()pH()pH()()pH()pH()()pH(NA.10) iiiiiiiniEiiEin22)()()pH()pH()()pH()()pH(NA.11) yDIN EN ISO 10523:2012-04 8 iiiinst

37、s2m2e)()(pH)pH()pH(1(NA.12) iists2me)( pH)pH(NA.13) with iin)pH(1pHmand 2)()pH()()( )(2eniEiiEiEsiiiThe factor t stands for the Students distribution t, the confidence level and n 2 degrees of freedom. 0,025 is assumed for . The value is taken from the relevant statistical tables. When calibrating w

38、ith five reference solutions t 3,18. The factor n represents the number of buffer solutions used. These equations correspond to the normal equations of classical regression and thus the usual assumptions of linear regression apply. Determine pH(X) from the parameters of the regression line, the slop

39、e and -intercept , and from the electrode voltage in the unknown solution, E(X), using Equation (NA.14). E (X)pH(X)(NA.14) Its uncertainty (which only contains the contribution from the scatter of the potentials of the reference solutions) is given by Equation (NA.15). gngistgssi11pH)pH(pHpH(X)pHpH(

40、X)(pH)(pH)212m2memuo(NA.15) with 22m2e2pH)pH(/iistg(NA.16) yDIN EN ISO 10523:2012-04 9 Numerically, s(pH)oand s(pH)uare somewhat different. For most measurements of the pH value this difference should only be noticeable in terms of insignificant decimal places. The term g in (NA.16) is very small (1

41、03to 104). Therefore, the leading term, (pH(X) pHm) g, may be neglected because the pH value is given to no more than two significant figures. Then s(pH)o s(pH)u s(pH). The value s(pH) roughly corresponds to the expanded uncertainty U with a coverage factor of k 2. NA.6 Example Measured values (n 5)

42、 pH(1) 4,01; E(1) 182,3 mV pH(2) 4,66; E(2) 140,5 mV pH(3) 7,00; E(3) 2,7 mV pH(4) 9,01; E(4) 113,2 mV pH(5) 10,01; E(5) 171,3 mV E(X) 100,0 mV The following totals are calculated from this: 34,69)pH(i27,50pH)pH(2m)( i6,94pHmmV41,0)(iE 329,991)()pH( )( iEi 268,18)pH(2i mV76,13895)(2iE3,18250,05;tCal

43、culate the mean -intercept of the reference line: mV415,51203,401268,18)(5329,99)1(34,6941,00)(268,18 )(Input quantities yDIN EN ISO 10523:2012-04 10 The mean slope is pHmV71,58)69,34()18,2685()0,4169,34()99,3291(52)(The standard deviation seis 53,23)99,329171,5800,4151,415(76,13895esThe 95 % level

44、of confidence (corresponds to the expanded standard uncertainty U) for the y-intercept is mV11,2427,50(6,94)0,22,533,182and for the slope 1,5327,502,533,18 An electrode voltage of 100,0 mV was measured in the solution with the unknown pH value. Thus pH(X) is calculated as follows: 5,3558,71415,51100

45、0pH(X) For the uncertainties s(pH)oand s(pH)uthe following apply 42221083,650,2753,2/71,5818,3gfor a 95 % confidence interval. 0,0741 0,0011,0051,0027,506,94)(5,3558,712,533,18106,836,94)(5,35(pH)(pH)24uossThe first term (5,35 6,94) 104 0,001 1 can be neglected. Thus, for the pH measurement this li

46、near regression equation can be simplified to s(pH)o s(pH)u s(pH) 0,071,0051,0027,506,94)(5,3558,712,533,18(pH(X)2Us(pH) corresponds to the expanded measurement uncertainty (k 2), so that U(pH(X) 0,07. 53.150.2753.218.3 DIN EN ISO 10523:2012-04 11 NOTE The multitude of numerical operations involved

47、in this, especially the subtraction of large numbers as products, makes these calculations sensitive to rounding errors. (For instance, the calculation of this example using a computer which uses single precision arithmetic gives a value of se 1,925 and g 3,961 104). It has been shown that the calculation of the standard deviation is particul