1、BRITISH STANDARDBS EN ISO 18412:2006Water quality Determination of chromium(VI) Photometric method for weakly contaminated waterThe European Standard EN ISO 18412:2006 has the status of a British StandardICS 13.060.50g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54
2、g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58BS EN ISO 18412:2006This British Standard was published under the authority of the Standards Policy and Strategy Committee on 29 September 2006 BSI 2006ISBN 0 580 49258 3National fore
3、wordThis British Standard was published by BSI. It is the UK implementation of EN ISO 18412:2006.The UK participation in its preparation was entrusted by Technical Committee EH/3, Water quality, to Subcommittee EH/3/2, Physical chemical and biochemical methods.A list of organizations represented on
4、EH/3/2 can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application.Compliance with a British Standard cannot confer immunity from legal obligations. Amendments issued since publ
5、icationAmd. No. Date CommentsEUROPEAN STANDARDNORME EUROPENNEEUROPISCHE NORMEN ISO 18412August 2006ICS 13.060.50English VersionWater quality - Determination of chromium(VI) - Photometricmethod for weakly contaminated water (ISO 18412:2005)Qualit de leau - Dosage du chrome(VI) - Mthodephotomtrique po
6、ur des eaux faiblement contamines (ISO18412:2005)Wasserbeschaffenheit - Bestimmung von Chrom(VI) -Photometrisches Verfahren fr gering belastetes Wasser(ISO 18412:2005)This European Standard was approved by CEN on 3 August 2006.CEN members are bound to comply with the CEN/CENELEC Internal Regulations
7、 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 St
8、andard 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 stand
9、ards 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.EUROPEA
10、N COMMITTEE FOR STANDARDIZATIONCOMIT EUROPEN DE NORMALISATIONEUROPISCHES KOMITEE FR NORMUNGManagement Centre: rue de Stassart, 36 B-1050 Brussels 2006 CEN All rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN ISO 18412:2006: EForeword The text
11、 of ISO 18412:2005 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 18412:2006 by Technical Committee CEN/TC 230 “Water analysis“, the secretariat of which is held by DIN. This European S
12、tandard 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. According to the CEN/CENELEC Internal Regulations, the nationa
13、l 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, Portu
14、gal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. Endorsement notice The text of ISO 18412:2005 has been approved by CEN as EN ISO 18412:2006 without any modifications. EN ISO 18412:2006Reference numberISO 18412:2005(E)INTERNATIONAL STANDARD ISO18412First edition2005-0
15、6-01Water quality Determination of chromium(VI) Photometric method for weakly contaminated water Qualit de leau Dosage du chrome(VI) Mthode photomtrique pour des eaux faiblement contamines EN ISO 18412:2006ii iiiContents Page Foreword iv Introduction v 1 Scope 1 2 Normative references . 1 3 Interfer
16、ences 1 4 Principle . 2 5 Reagents 2 6 Apparatus. 3 7 Sampling and sample pretreatment 3 8 Procedure. 3 9 Evaluation 4 10 Expression of results 4 11 Test report 5 Annex A (informative) Precision data. 6 EN ISO 18412:2006iv Foreword ISO (the International Organization for Standardization) is a worldw
17、ide 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 th
18、at 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
19、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 r
20、equires 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 18412 was prepared by Tech
21、nical Committee ISO/TC 147, Water quality, Subcommittee SC 2, Physical, chemical and biochemical methods. EN ISO 18412:2006vIntroduction The user should be aware that particular problems could require the specification of additional conditions. EN ISO 18412:2006blank1Water quality Determination of c
22、hromium(VI) Photometric method for weakly contaminated water WARNING Persons using this International Standard should be familiar with normal laboratory practice. This International Standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibi
23、lity of the user to establish appropriate safety and health practices and to ensure compliance with any national regulatory conditions. Care should be taken in handling potassium dichromate due to its carcinogenicity. IMPORTANT It is absolutely essential that tests conducted according to this standa
24、rd be carried out by suitably trained staff. 1 Scope This International Standard specifies a method for the determination of chromium(VI) in drinking water in mass concentrations between 2 g/l and 50 g/l. For the determination of higher concentrations, the sample is diluted prior to analysis. The me
25、thod may also be applied to weakly polluted ground and surface water, provided the matrix does not contain interfering reducing agents. This method has not been verified for estuarine water and seawater, so the user is responsible for the validation of the method for these matrices. The photometric
26、determination of chromium(VI) in waste water is carried out according to ISO 11083, Water quality Determination of chromium(VI) Spectrometric method using 1,5-diphenylcarbazide. 2 Normative references The following referenced documents are indispensable for the application of this document. For date
27、d references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 3696, Water for analytical laboratory use Specification and test methods ISO 5667-1, Water quality Sampling Part 1: Guidance on the design of sa
28、mpling programmes ISO 5667-2, Water quality Sampling Part 2: Guidance on sampling techniques ISO 5667-3, Water quality Sampling Part 3: Guidance on the preservation and handling of samples ISO 8466-1, Water quality Calibration and evaluation of analytical methods and estimation of performance charac
29、teristics Part 1: Statistical evaluation of the linear calibration function ISO 8466-2, Water quality Calibration and evaluation of analytical methods and estimation of performance characteristics Part 2: Calibration strategy for non-linear second-order calibration functions 3 Interferences Reducing
30、 agents in the sample may lead to negative bias for the chromium(VI) concentration. Concentrations of sulfide up to 0,2 mg/l do not interfere. EN ISO 18412:20062 Oxidizing agents for disinfection in drinking water production, such as chlorine, chlorine dioxide, ozone and hydrogen peroxide, do not in
31、terfere with the method, provided their mass concentration does not exceed the concentrations given in Table 1. Table 1 Mass concentrations of disinfection agents not producing significant interference under the given measuring conditions Concentration Disinfectant mg/l Chlorine 0,6 Chlorine dioxide
32、 0,4 Hydrogen peroxide 0,2 Ozone 0,1 4 Principle Chromium(VI) oxidizes 1,5-diphenylcarbazide to 1,5-diphenylcarbazone which forms a red-violet complex with chromium. The relationship between the absorbance of the complex and the chromium(VI) concentration is linear. The maximum absorbance is measure
33、d at 540 nm. 5 Reagents Use only reagents of recognized analytical grade. 5.1 Water, complying with grade 1 as defined in ISO 3696, or distilled water or water of equivalent purity. 5.2 Sulfuric acid, (H2SO4) 1,81 g/ml. 5.3 Orthophosphoric acid, (H3PO4) 1,71 g/ml. 5.4 Acid mixture, H2SO4/H3PO4. Into
34、 a 500 ml volumetric flask introduce about 200 ml of water (5.1). Add 27 ml of sulfuric acid (5.2) and 33 ml of orthophosphoric acid (5.3), mix and dilute to volume with water (5.1). 5.5 Propanone (acetone), C3H6O. 5.6 Diphenylcarbazide (DPC reagent), 1 % solution in acetone (5.5). Dissolve 1 g of 1
35、,5-diphenylcarbazide (C13H14N4O) in 100 ml of acetone (5.5). Stored in a brown bottle in a refrigerator, + 2C to + 8C, the reagent is stable for about 1 week. 5.7 Potassium chromate stock solution, Cr(VI) = 1 g/l. In a 1 000 ml volumetric flask, dissolve 3,735 g K2CrO4in water (5.1) and dilute to vo
36、lume with water (5.1). The solution is, when stored at room temperature, stable for at least 1 year. 5.8 Potassium chromate standard solution I, Cr(VI) = 100 mg/l. Pipette 50 ml of potassium chromate stock solution (5.7) into a 500 ml volumetric flask, and dilute to volume with water (5.1). EN ISO 1
37、8412:20063Prepare the standard solution on the day of use. 5.9 Potassium chromate standard solution II, Cr(VI) = 4 mg/l. Pipette 20 ml of potassium chromate standard solution (I) (5.8) into a 500 ml volumetric flask, and dilute to volume with water (5.1). Prepare the solution on the day of use. 6 Ap
38、paratus Usual laboratory apparatus and the following. 6.1 Volumetric flasks, of nominal volume 50 ml, 500 ml or 1 000 ml. 6.2 Volumetric pipettes, of nominal volume 25 ml, 40 ml or 50 ml. 6.3 Automatic pipette, nominal value 500 l. 6.4 Photometer, equipped with cells of optical path length 50 mm, or
39、 filter photometer. 7 Sampling and sample pretreatment Take samples as specified in ISO 5667-1, ISO 5667-2 and ISO 5667-3. Store the samples in the refrigerator and analyse them within 4 days after sampling. The sample should not contain more than 50 g/l of chromium(VI). Dilute the sample appropriat
40、ely if the concentration is 50 g/l. 8 Procedure 8.1 Measurement Pipette 40 ml of the sample into a 50 ml volumetric flask. Add 4 ml of acid mixture (5.4), swirl to mix, add 500 l of DPC reagent (5.6), and mix again. Dilute to volume with water (5.1) (absorbance A1, see Clause 9). Treat a blank for e
41、ach batch of samples in the same way, by replacing the 40 ml of sample by 40 ml of water (5.1) (absorbance A2, see Clause 9). If the absorbance A2exceeds 0,005, take the necessary steps to reduce the blank (e.g. by preparing new reagents). For compensation of a possible absorbance of the sample, pre
42、pare an additional sample by pipetting 40 ml of the sample into a 50 ml measuring flask, add 4 ml of the acid mixture, but omit the addition of DPC reagent, swirl and dilute to volume with water (5.1) (absorbance A3, see Clause 9). Let the samples stand for 5 min to 20 min and, using the photometer
43、(6.4), measure the absorbance at 540 nm against water (5.1) in the reference cell. NOTE If other sample volumes are used, the volumes of the reagents need to be adjusted appropriately. EN ISO 18412:20064 8.2 Calibration according to the standard calibration procedure For a working range of 5 g/l to
44、50 g/l, proceed, for example, as follows: Into five 50 ml volumetric flasks, pipette between 50 l and 500 l (equidistant concentration steps) of the potassium chromate standard solution II (5.9). Add water (5.1) to complete to about 40 ml. Add, to each flask, 4 ml of the acid mixture (5.4), and swir
45、l thoroughly to mix. Then add, to each flask, 500 l of DPC reagent (5.6) and swirl to mix. Dilute to volume with water (5.1). After 5 min to 20 min, measure the absorbance in a photometer (6.4) at 540 nm against water (5.1) in the reference cell. From the measurements, evaluate the linear regression
46、 line as specified in ISO 8466-1. Check the calibration graph regularly, especially when new batches of reagents are used. If a linear regression line is not achieved, it is also possible to evaluate as specified in ISO 8466-2 (non-linear second-order calibration function). 9 Evaluation Calculate th
47、e mass concentration of chromium(VI), expressed in micrograms per litre (g/l), in the water sample using Equation (1): 123A AAb= (1) where is the mass concentration, in micrograms per litre (g/l), of chromium (VI); A1is the absorbance of the sample at 540 nm; A2is the absorbance of the blank at 540
48、nm; A3is the absorbance of the sample without added DPC at 540 nm; b is the sensitivity, i.e. the slope of the calibration curve, in litres per microgram (l/g). The evaluation refers to a sample volume of 40 ml. Deviating sample volumes or dilutions need appropriate correction. 10 Expression of resu
49、lts Values are rounded to the appropriate number of significant figures (e.g. 1 g/l). EXAMPLE Chromium(VI) = 5 g/l; Chromium(VI) = 12 g/l. EN ISO 18412:2006511 Test report The test report shall include at least the following information: a) a reference to this International Standard (ISO 18412); b) identification of the sample; c) results according to Clause 10; d) sample pretreatment, if applicable; e) any deviation from this procedure and information on all circumstances that may ha
