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1、 Reference number ISO 16264:2002(E) ISO 2002 INTERNATIONAL STANDARD ISO 16264 First edition 2002-05-15 Water quality Determination of soluble silicates by flow analysis (FIA and CFA) and photometric detection Qualit de leau Dosage des silicates solubles par analyse en flux (FIA et CFA) et dtection p
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5、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. ISO 2002 All rights res
6、erved. 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 ISOs member body in the country of the reque
7、ster. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.ch Web www.iso.ch Printed in Switzerland ii ISO 2002 All rights reserved Copyright International Organization for Standardization Provided by IHS under license with ISO Licen
8、see=NASA Technical Standards 1/9972545001 Not for Resale, 04/20/2007 04:23:29 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 16264:2002(E) ISO 2002 All rights reserved iii Contents Page Foreword.iv Introduction.v 1 Scope1 2 Normative references1 3 General interferences
9、1 4 Principle2 5 Reagents.2 6 Apparatus.4 7 Sampling and sample preparation.7 8 Procedure.7 9 Calculation .9 10 Precision.9 11 Test report10 Bibliography11 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 N
10、ot for Resale, 04/20/2007 04:23:29 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 16264:2002(E) iv ISO 2002 All rights reserved Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies).
11、 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-
12、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
13、3. 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
14、 vote. Attention is drawn to the possibility that some of the elements of this International Standard may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO 16264 was prepared by Technical Committee ISO/TC 147, Water quality, Subcomm
15、ittee SC 2, Physical, chemical, biochemical methods. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/20/2007 04:23:29 MDTNo reproduction or networking permitted without license from IHS
16、-,-,- ISO 16264:2002(E) ISO 2002 All rights reserved v Introduction Further investigation will be necessary to determine whether and to what extent particular problems will require the specification of additional minor conditions. It is absolutely essential that tests conducted according to this Int
17、ernational Standard be carried out by suitably qualified staff. Differentiation is required between flow injection analysis (FIA)1, 2, and continuous flow analysis (CFA) 3. Both methods share the feature of an automatic dosage of the sample into a flow system (manifold) where the analytes in the sam
18、ple react with the reagent solutions on their way through the manifold. The sample preparation may be integrated into the manifold. The reaction product is determined in a flow detector (e.g. photometer). This detector produces a signal from which the concentration of the parameter can be calculated
19、. Methods using flow analysis automate wet chemical procedures and are particularly suitable for processing many analytes in water in large sample series at a high analysis frequency. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Techni
20、cal Standards 1/9972545001 Not for Resale, 04/20/2007 04:23:29 MDTNo reproduction or networking permitted without license from IHS -,-,- Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/2
21、0/2007 04:23:29 MDTNo reproduction or networking permitted without license from IHS -,-,- INTERNATIONAL STANDARD ISO 16264:2002(E) ISO 2002 All rights reserved 1 Water quality Determination of soluble silicates by flow analysis (FIA and CFA) and photometric detection WARNING Persons using this Inter
22、national 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 responsibility of the user to establish appropriate safety and health practices and to ensure complianc
23、e with any national regulatory conditions. 1 Scope This International Standard specifies two methods, i.e. flow injection analysis (FIA) and continuous flow analysis (CFA), for the determination of soluble silicate ions in various types of water (such as ground, drinking, surface, leachate and waste
24、 water). Both methods are applicable to the determination of a mass concentration of silicate (SiO2) ranging from 0,2 mg/l to 20 mg/l (with working ranges 0,2 mg/l to 2,0 mg/l and 2 mg/l to 20 mg/l). Other mass concentration ranges are applicable, provided they cover exactly one decade of concentrat
25、ion units (e.g. 0,02 mg/l to 0,2 mg/l in SiO2). These methods can be made applicable to seawater by changing the sensitivity and by adapting the reagent and calibration solutions to the salinity of the samples. 2 Normative references The following normative documents contain provisions which, throug
26、h reference in this text, constitute provisions of this International Standard. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this International Standard are encouraged to investigate the possibility o
27、f applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC maintain registers of currently valid International Standards. ISO 3696:1987, Water for analytical laborato
28、ry use Specification and test methods ISO 5725-2:1994, Accuracy (trueness and precision) of measurement methods and results Part 2: Basic method for the determination of repeatability and reproducibility of a standard measurement method ISO 8466-1:1990, Water quality Calibration and evaluation of an
29、alytical methods and estimation of performance characteristics Part 1: Statistical evaluation of the linear calibration function 3 General interferences Tannin, large amounts of iron, sulfide and phosphate interfere. The treatment with oxalic acid reduces the interference from tannin and eliminates
30、interference from phosphate provided the mass concentrations are 150 mg/l, treat the samples with boric acid. High concentrations of oxidizing agents are destroyed by adding 1 mol/l of sodium sulfite solution prior to analysis. If the sample contains large concentrations of sulfide, e.g. 5 mg/l, spe
31、cial provisions are necessary. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/20/2007 04:23:29 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 16264:2002(E
32、) 2 ISO 2002 All rights reserved 4 Principle 4.1 FIA method The sample is injected into a carrier stream of water by means of a valve. An acidic solution of heptamolybdate is added to the sample and reacts with silicates and phosphates to form molybdosilicate and molybdophosphoric acid. The latter i
33、s destroyed by oxalic acid. The molybdosilicate is then reduced to molybdenum blue using a tin(II) chloride solution. The result is expressed in milligrams of SiO2 per litre of water. 4.2 CFA method An acidic solution of heptamolybdate is added to the sample and reacts with silicates and phosphates
34、to form molybdosilicate and molybdophosphoric acid. The latter is destroyed by oxalic acid. The molybdosilicate is then reduced to molybdenum blue using ascorbic acid. The result is expressed in milligrams of SiO2 per litre of water. 5 Reagents Use analytical grade chemicals unless otherwise specifi
35、ed. Check the silicate blank value of the water and of the reagents (8.2.1). Carefully degas all reagent solutions, e.g. by vacuum filtration or by purging with helium (about 1 min). Use only polyethene or polypropene laboratory ware (flasks, beakers and pipettes) for the preparation and storage of
36、the samples (see clause 7), water (5.1) and the solutions 5.8, 5.9 and 5.10. 5.1 Water, complying with purity grade 1 of ISO 3696. 5.2 Sulfuric acid (H2SO4), (H2SO4) = 1,84 g/ml. 5.3 Molybdate solution, (see R1 in Figures 1 and 2). In a 1 000 ml volumetric flask, dissolve (30 0,3) g of hexaammonium
37、heptamolybdate tetrahydrate, (NH4)6Mo7O244H2O, in about 800 ml of water (5.1). Add 15 ml of sulfuric acid (5.2) and dilute to volume with water. The solution may be stored for up to 3 months at room temperature. Discard the solution if precipitation or coloration occurs. 5.4 Oxalic acid solution, (s
38、ee R2 in Figures 1 and 2). In a 1 000 ml volumetric flask, dissolve (44 0,4) g of oxalic acid dihydrate, C2H2O42H2O, in about 800 ml of water (5.1) and dilute to volume with water. The solution may be stored up to 3 months at room temperature. 5.5 Tin(II) chloride reagent, for the determination of s
39、ilicate by FIA (see R3 in Figure 1). Slowly add 28 ml of sulfuric acid (5.2) to 800 ml water (5.1) in a 1 000 ml volumetric flask. Dissolve (240 2) mg of tin(II) chloride dihydrate, SnCl22H2O, and (2 0,02) g of hydrazine sulfate, N2H6SO4, in this solution. Cool to room temperature and dilute to volu
40、me with water. The solution is stable for 1 month if stored at (4 2) C. 5.6 Ascorbic acid solution, for the determination of silicate using CFA (see R3 in Figure 2). Dissolve (4 0,04) g of ascorbic acid, C6H8O6, in about 80 ml of water (5.1) and dilute to 100 ml with water. Prepare the solution fres
41、hly before use. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/20/2007 04:23:29 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 16264:2002(E) ISO 2002 All
42、rights reserved 3 5.7 Surfactant solutions for CFA systems: 5.7.1 Surfactant solution I, for a working range I (0,2 mg/l to 2,0 mg/l; see C in Figure 2). In a 1 000 ml volumetric flask, dissolve (10 0,1) g of sodium dodecyl sulfate, NaC12H25O4S, in about 800 ml of water (5.1) and dilute to volume wi
43、th water. The solution may be stored for up to 6 months at room temperature. 5.7.2 Surfactant solution II, for working range II (2 mg/l to 20 mg/l; see B in Figure 2). In a 1 000 ml volumetric flask, dissolve (1 0,01) g of sodium dodecyl sulfate, NaC12H25O4S, in about 800 ml of water (5.1) and dilut
44、e to volume with water. The solution may be stored for up to 6 months at room temperature. 5.8 Alkaline silicate solution, containing 0,500 0 g/l, expressed as SiO2 (e.g. SiCl4 in 0,1 mol/l of sodium hydroxide solution, NaOH, or sodium metasilicate nonahydrate, Na2SiO3 9H2O). The solution is stable
45、for 6 months if stored at room temperature. NOTE A typical procedure for preparing the alkaline silicate solution from silicium tetrachloride, SiCl4 is the following. While cooling intensively, dissolve (1,415 0,001) g of SiCl4 for synthesis (commercially available). In small portions in about 900 m
46、l of 0,1 mol/l sodium hydroxide solution, NaOH. Dilute to volume with 0,1 mol/l sodium hydroxide solution. 5.9 Silicate stock solution, = 50 mg/l (expressed as SiO2). In a 1 000 ml volumetric flask, dilute 100 ml of alkaline silicate solution (5.8) with water (5.1) and dilute to volume with water. T
47、he solution is stable for 6 months if stored at room temperature. 5.10 Calibration solutions. Prepare at least five calibration solutions by diluting the silicate stock solution (5.9) with water (5.1) for the required range. The concentrations of the solutions shall be distributed equidistantly over
48、 the corresponding working range (see ISO 8466-1). Tables 1 and 2 give examples for the preparation of ten calibration solutions for the working ranges I (0,2 mg/l to 2,0 mg/l) and II (2 mg/l to 20 mg/l SiO2). Table 1 Typical preparation scheme of silicate calibration solutions for working range I (0,2 mg/l to 2,0 mg/l SiO2) Volume (ml) of silicate stock solution (5.9) diluted to 1 000 ml 4 8 12 16 20 24 28 32 36 40 Mass concentration of calibration s