ISO TS 15923-2-2017 Water quality - Determination of selected parameters by discrete analysis systems - Part 2 Chromium(VI) fluoride total alkalinity total hard.pdf

1、 ISO 2017 Water quality Determination of selected parameters by discrete analysis systems Part 2: Chromium(VI), fluoride, total alkalinity, total hardness, calcium, magnesium, iron, iron(II), manganese and aluminium with photometric detection Qualit de leau Dtermination de paramtres slectionns par d

2、es systmes danalyse discrte Partie 2: Chrom(VI), fluorure, alcalinit totale, duret totale, calcium, magnsium, fer, (fer(II), manganse et aluminium avec dtection photomtrique TECHNICAL SPECIFICATION ISO/TS 15923-2 Reference number ISO/TS 15923-2:2017(E) First edition 2017-10 ISO/TS 15923-2:2017(E)ii

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5、2 749 09 47 copyrightiso.org www.iso.org ISO/TS 15923-2:2017(E)Foreword iv Introduction v 1 Scope . 1 2 Normative references 1 3 Terms and definitions . 1 4 Principle 2 5 Interferences 2 6 Reagents 2 7 Apparatus . 2 8 Sampling and sample preparation 3 9 Calibration 3 9.1 Calibration function 3 9.2 C

6、alibration validity check 4 10 Procedure. 4 11 Calculation 4 12 Expression of results 4 13 Test report . 4 Annex A (normative) Correction for inherent colour . 6 Annex B (normative) Chromium(VI) 7 Annex C (normative) Fluoride . 9 Annex D (normative) Total alkalinity .12 Annex E (normative) Total har

7、dness .14 Annex F (normative) Calcium .17 Annex G (normative) Magnesium .19 Annex H (normative) Iron(II) and iron (total) 21 Annex I (normative) Manganese 24 Annex J (normative) Aluminium 28 Bibliography .31 ISO 2017 All rights reserved iii Contents Page ISO/TS 15923-2:2017(E) Foreword ISO (the Inte

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14、wing URL: www.iso.org/iso/foreword.html. This document was prepared by Technical Committee ISO/TC 147, Water quality, Subcommittee SC 2, Physical, chemical and biochemical methods. A list of all parts in the ISO 15923 series can be found on the ISO website.iv ISO 2017 All rights reserved ISO/TS 1592

15、3-2:2017(E) Introduction Many photometric determinations can be automated with a discrete analysis system. With a single instrument, a large number of different parameters can be determined, and a different combination can be specified for each sample. Working with small volumes requires less sample

16、 material and reagent. Samples that fall outside the normal range of measurement can either be automatically diluted or analysed using a different measuring range. ISO 2017 All rights reserved v Water quality Determination of selected parameters by discrete analysis systems Part 2: Chromium(VI), flu

17、oride, total alkalinity, total hardness, calcium, magnesium, iron, iron(II), manganese and aluminium with photometric detection 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, associ

18、ated with its use. It is the responsibility of the user to establish appropriate safety and health practices. IMPORTANT It is absolutely essential that tests conducted in accordance with this document be carried out by suitably qualified staff. 1 Scope This document specifies methods for the automat

19、ic determination of chromium(VI), fluoride, total alkalinity, total hardness, calcium, magnesium, iron, iron(II), manganese and aluminium with photometric determination using a discrete analysis system. The field of application is water (ground, potable, surface, waste, eluates and boiler water). Th

20、e method can also be applied to marine waters with matrix matching of standard and control solutions. Note that some parameters, notably iron, manganese and aluminium and possibly chromium(VI), calcium and magnesium may not be completely quantified if the sample contains particulates. Samples can be

21、 digested in acid, as long as the buffering capacity of the reaction mixture is not exceeded. Such procedures are beyond the scope of this document, which is best suited to the determination of dissolved metals following on-site filtration. 2 Normative references The following documents are referred

22、 to in the text in such a way that some or all of their content constitutes requirements 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 3696, Water for analytical la

23、boratory use Specification and test methods ISO 8466-1, Water quality Calibration and evaluation of analytical methods and estimation of performance characteristics Part 1: Statistical evaluation of the linear calibration function ISO 8466-2, Water quality Calibration and evaluation of analytical me

24、thods and estimation of performance characteristics Part 2: Calibration strategy for non-linear second-order calibration functions 3 Terms and definitions No terms and definitions are listed in this document. ISO and IEC maintain terminological databases for use in standardization at the following a

25、ddresses: ISO Online browsing platform: available at https:/ /www.iso.org./obp IEC Electropedia: available at http:/ /www.electropedia.org/ TECHNICAL SPECIFICATION ISO/TS 15923-2:2017(E) ISO 2017 All rights reserved 1 ISO/TS 15923-2:2017(E) 4 Principle A discrete analysis system is an automated syst

26、em for spectrophotometric and turbidimetric determinations. The colour reactions take place in reaction cells, which may be cuvettes, in an incubator. For each determination, a separate reaction cell is used. Pre-set volumes of the sample and the reagents are pipetted into the cells and mixed. Follo

27、wing the incubation period, the absorbance of the solution is measured at the wavelength applicable to the determination. Depending on which instrument is used, measurement is achieved by passing the cuvettes through the photometer or by transferring the measuring solution from the reaction cells to

28、 a photometer with a flow-through cell. The specific chemistry for each parameter is given in the relevant annex. 5 Interferences Particles present in the sample can lead to blockages and will interfere with the photometric measurement. Filtration of samples containing particles through a 0,45 m mem

29、brane filter is recommended. Particles can also be removed by settlement, centrifugation or dialysis. If the sample is filtered prior to analysis, the fraction of any of the parameters that is adsorbed onto the surface of particles will not be measured. Inherent colour or turbidity of the sample can

30、 interfere with the analysis. Two possible procedures to correct for any inherent colour are described in Annex A. A reliable procedure for the correction of turbidity cannot really be given. The Beer-Lambert law does not apply to turbid solutions. Furthermore, many chromogenic reagents and coloured

31、 complexes are adsorbed on particles. Interferences specific to each parameter are discussed in the relevant annex. 6 Reagents Reagents for each parameter are specified in Annexes B to J. Use only reagents of recognized analytical grade, unless otherwise specified in the relevant annex. Dry all soli

32、d reagents to constant weight at (105 5) C, provided that they are thermally stable. Store the dried solid in an exsiccator before weighing. Reagent volumes specified in Annexes B to J may be adjusted to suit local requirements or different instrument specifications. For many of the reagents, calibr

33、ation and control standards specified in this document, commercial preparations are available and it is quite acceptable to use them provided that manufacturers instructions relating to storage and stability are followed. 6.1 Water, complying with the specification for grade 1 as defined in ISO 3696

34、. 7 Apparatus 7.1 Discrete analysis system, generally consisting of the following components. 7.1.1 Sample injection device, for automated or manual operation. 7.1.2 Sample container. 7.1.3 Reagent container, refrigerated or not.2 ISO 2017 All rights reserved ISO/TS 15923-2:2017(E) 7.1.4 Incubator w

35、ith temperature control, capable of maintaining a constant temperature. 7.1.5 Visible wavelength detector, e.g. spectrophotometer, suitable for a wavelength range usually between 400 nm and 880 nm. 7.1.6 Control and data processing unit. 7.1.7 Recording device, e.g. PC with software for data acquisi

36、tion and evaluation. 7.2 Routine laboratory apparatus, including 7.2.1 Balance, capable of measuring to 0,000 1 g. 7.2.2 Oven. 7.2.3 Exsiccator. 7.2.4 Glassware, including volumetric flasks and beakers. 7.2.5 Autopipettes, capable of dispensing volumes from 50 l to 500 l. 8 Sampling and sample prepa

37、ration Use clean vessels for sampling. Turbidity or particulates interfere with spectrophotometric detection. Using an appropriate filtration apparatus, clarify any samples containing particles by filtering through a 0,45 m membrane (settlement, centrifugation or dialysis may also be used). To avoid

38、 contamination by the filter membrane, discard the first few millilitres of filtrate. ISO 5667-3 offers guidance on the preparation and storage of samples. However, the stability of some of the parameters covered by this document may vary according to conditions such as the pH and other constituents

39、 present in the sample. Stability trials should be carried out locally for each matrix type. The guidance in ISO 5667-3 for preservation of samples for iron, manganese, aluminium, calcium and magnesium recommends acidifying the sample to between pH 1 and 2, but this may not be appropriate for discre

40、te analysis methods where pH is critical, e.g. calcium and manganese. In such cases, it is important to ensure that the buffering capacity of the reaction mixture is not exceeded. Fluoride is stable for at least one month with no pre-treatment. For chromium(VI), best practice is to analyse the sampl

41、e as soon as possible after sampling. ISO 18412 2recommends a maximum of 4 d refrigerated storage, but ISO 23913 3specifies storage for no more than 24 h at 2 C to 5 C. Prepare a sample of water (6.1) in the same way as the sample, to be used as a blank. Prepare a control standard solution from the

42、primary control standard containing a level of analyte similar to the samples. Run it as a sample at appropriate intervals in the batch, according to local requirements. A minimum interval of once every 20 samples is recommended. Instructions for preparing a primary control standard are given in Ann

43、exes B to J. 9 Calibration 9.1 Calibration function When the analytical system is first evaluated and at intervals afterwards, establish a calibration function for each parameter (see ISO 8466-1 or ISO 8466-2) as follows. ISO 2017 All rights reserved 3 ISO/TS 15923-2:2017(E) Using the primary calibr

44、ation standard, prepare an appropriate series of calibration solutions (Annexes B to J). Use water (6.1) as a zero concentration calibration solution. Analyse the calibration solutions according to Clause 9 and the instrument manufacturers instructions. Confirm the validity of the data obtained, and

45、 use to calculate the regression line as specified in ISO 8466-1 or ISO 8466-2. During the analysis, verify the continuing validity of the established calibration function by analysing an appropriate calibration standard solution, at regular intervals according to local accuracy requirements, or at

46、least at the end of the batch. Recalibrate, if necessary. It is recommended that calibration verification is carried out using a calibration solution in the upper third of the calibration range. 9.2 Calibration validity check If the full calibration function is not established daily, carry out an in

47、itial calibration validity check by analysing two calibration standard solutions in the lower and upper third of the calibrated working range (see Clause 10). Verify the continuing validity of the established calibration function as described in 9.1. 10 Procedure Set up the discrete analysis system

48、according to the instrument manufacturers instructions. Calibrate the system according to Clause 9 and the instrument manufacturers instructions. Prepare the samples according to Clause 8 and Annexes B to J. A consistent incubation temperature and time are essential for the stability of the absorban

49、ce measurements. Measure the absorbance of the samples using the instrument manufacturers recommended instructions. Measure the blank according to Annex A and the instrument manufacturers instructions. If the absorbance of a sample exceeds that of the top calibration solution, dilute the sample using water (6.1), or reduce the sample intake by an appropriate factor to bring it into the upper half of the calibration range, and reanalyse. If necessary, subtract the absorbance of the blank from that