BS ISO 17289-2014 Water quality Determination of dissolved oxygen Optical sensor method《水质 溶解氧的测定 光学传感器法》.pdf

1、BSI Standards PublicationBS ISO 17289:2014Water quality Determinationof dissolved oxygen Opticalsensor methodBS ISO 17289:2014 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 17289:2014.The UK participation in its preparation was entrusted to TechnicalCommittee

2、 EH/3/2, Physical chemical and biochemical methods.A list of organizations represented on this committee can beobtained on request to its secretary.This publication does not purport to include all the necessaryprovisions of a contract. Users are responsible for its correctapplication. The British St

3、andards Institution 2014. Published by BSI StandardsLimited 2014ISBN 978 0 580 76084 6ICS 13.060.50Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of theStandards Policy and Strategy Committee on 31 July 2014.Ame

4、ndments issued since publicationDate Text affectedBS ISO 17289:2014 ISO 2014Water quality Determination of dissolved oxygen Optical sensor methodQualit de leau Dosage de loxygne dissous Mthode optique la sondeINTERNATIONAL STANDARDISO17289First edition2014-07-01Reference numberISO 17289:2014(E)BS IS

5、O 17289:2014ISO 17289:2014(E)ii ISO 2014 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2014All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or post

6、ing on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below or ISOs member body in the country of the requester.ISO copyright officeCase postale 56 CH-1211 Geneva 20Tel. + 41 22 749 01 11Fax + 41 22 749 09 47E-mail copyrighti

7、so.orgWeb www.iso.orgPublished in SwitzerlandBS ISO 17289:2014ISO 17289:2014(E) ISO 2014 All rights reserved iiiContents PageForeword iv1 Scope . 12 Normative references 13 Principle 14 Interferences 25 Reagents 26 Apparatus . 27 Procedure. 37.1 Sampling . 37.2 Measuring technique and precautions to

8、 be taken . 37.3 Calibration 47.4 Determination . 48 Calculation and expression of results . 58.1 Dissolved oxygen concentration 58.2 Dissolved oxygen expressed as percentage saturation 59 Test report . 5Annex A (informative) Physico-chemical data of oxygen in water 7Annex B (informative) Performanc

9、e data 13Bibliography .14BS ISO 17289:2014ISO 17289:2014(E)ForewordISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committe

10、es. 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-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the Inte

11、rnational Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.The procedures used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the dif

12、ferent types of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO sha

13、ll not be held responsible for identifying any or all such patent rights. Details of any patent rights identified during the development of the document will be in the Introduction and/or on the ISO list of patent declarations received (see www.iso.org/patents).Any trade name used in this document i

14、s information given for the convenience of users and does not constitute an endorsement.For an explanation on the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs adherence to the WTO principles in the Technical Barriers to Trade (TBT)

15、 see the following URL: Foreword - Supplementary informationThe committee responsible for this document is ISO/TC 147, Water quality, Subcommittee SC 2, Physical, chemical and biochemical methods.iv ISO 2014 All rights reservedBS ISO 17289:2014INTERNATIONAL STANDARD ISO 17289:2014(E)Water quality De

16、termination of dissolved oxygen Optical sensor methodWARNING 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 responsibility of

17、the user to establish appropriate safety and health practices and to ensure compliance with any national regulatory conditions.IMPORTANT It is absolutely essential that tests conducted in accordance with this International Standard be carried out by suitably trained staff.1 ScopeThis International S

18、tandard specifies an optical method for the determination of dissolved oxygen in water using a sensor working on the basis of fluorescence quenching.Measurement can be made either as a concentration of oxygen in milligrams per litre, percentage saturation (% dissolved oxygen), or both. Depending on

19、the instrument used, detection limits of 0,1 mg/l or 0,2 mg/l can be reached according to the manufacturers manual. Most instruments permit measurement of values higher than 100 %, i.e. supersaturation.NOTE Supersaturation is possible when the partial pressure of oxygen is higher than in air. Especi

20、ally in case of strong algae growth, supersaturation up to 200 % and more is possible.If waters with a saturation higher than 100 % are measured, it is essential to make arrangements to prevent the outgassing of oxygen during the handling and measurement of the sample. Similarly, it is important tha

21、t the transport of oxygen into the sample is prevented if the saturation is below 100 %.The method is suitable for measurements made in the field and for continuous monitoring of dissolved oxygen as well as measurements made in the laboratory. It is one of the preferred methods for highly coloured a

22、nd turbid waters, and also for analysis of waters not suitable for the Winkler titration method because of iron- and iodine-fixing substances, which can interfere in the iodometric method specified in ISO 5813.The method is suitable for drinking waters, natural waters, waste waters, and saline water

23、s. If used for saline waters such as sea or estuarine waters, a correction for salinity is essential for concentration measurement of oxygen.2 Normative referencesThe following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For

24、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 laboratory use Specification and test methods3 PrincipleOptical sensors that measure luminescence/fluorescence lif

25、etime or luminescence/fluorescence phase shift are normally composed of a luminophore or fluorescent dye situated in a sensor cap, a light source e.g. a light emitting diode (LED), and a photodetector. The pulsed or modulated light from the source causes excitation of the luminophore, which is quenc

26、hed in the presence of oxygen. The photodetector converts the resulting light emission into an electrical signal that can be sampled and processed to ISO 2014 All rights reserved 1BS ISO 17289:2014ISO 17289:2014(E)compute the phase shift or fluorescence or luminescence lifetime. This phase shift or

27、excitation lifetime is used to quantify dissolved oxygen concentrations.Temperature has two different influences. The first influence relates to the variation of the quenching process of the membrane with the temperature. So the primary signal of the probe has to be compensated with a built-in tempe

28、rature sensor. State-of-the-art meters are able to do this automatically. The second influence is given by the sample and the temperature dependence of the solubility of oxygen in it. Also salinity can have a significant effect.For calculating the percentage of saturation of samples being in contact

29、 with an atmosphere, it is necessary to take the atmospheric pressure into account. This can be performed manually or by implementing a pressure sensor for automatic compensation.Most sensors have a second LED to be used as internal reference for compensation purposes.4 InterferencesNo interferences

30、 in waters as described in Clause 1.5 ReagentsDuring analysis (i.e. for calibration), use only reagents of analytical grade.5.1 Water, grade 2, as specified in ISO 3696.5.2 Sodium sulfite, anhydrous, Na2SO3, or heptahydrate, Na2SO37H2O.5.3 Cobalt(II) salt, for example cobalt(II) chloride hexahydrate

31、, CoCl26H2O.5.4 Ascorbic acid.5.5 Sodium hydroxide solution, NaOH, c = 1 mol/l.5.6 Nitrogen gas, N2, purity 99,995 % or better.6 Apparatus6.1 Measuring instrument, comprising the following components.6.1.1 Measuring probe.Probe designs vary in the wavelength of the excitation light and the luminopho

32、re or fluorescent dye.6.1.2 Meter to show the mass concentrations of dissolved oxygen directly and/or percentage saturation with oxygen.6.2 Thermometer, graduated to at least 0,5 C.NOTE Commonly, a temperature sensor is integrated into the instrument.6.3 Barometer, graduated to 1 hPa.NOTE Usually, t

33、he barometer is integrated into the instrument.2 ISO 2014 All rights reservedBS ISO 17289:2014ISO 17289:2014(E)7 Procedure7.1 Sampling7.1.1 GeneralNormally, the oxygen concentration shall be measured directly on-site in the water body to be analysed.If direct measuring in the water body is not possi

34、ble, the measuring can also take place in a gastight connected flow-through device or immediately after fit for purpose sampling as a discrete sample.Any discrete sampling procedure will result in a higher measurement uncertainty.While filling the sample vessel during sampling, oxygen uptake or oxyg

35、en stripping shall be minimized. Sample transfer shall occur without any turbulence, i.e. by maintaining a laminar flow.7.1.2 Dip sampling (e.g. surface waters)Take the sample by carefully and slowly dipping the sample vessel.7.1.3 Sampling using faucetsConnect an inert sampling tube gastight to the

36、 faucet and insert the sampling tube all the way down to the bottom of the sampling vessel. Allow the water to overflow up to at least three times the volume of the vessel capacity.NOTE A sampling vessel can be filled with water before the measurement of the oxygen concentration, provided that turbu

37、lence is avoided.7.1.4 Sampling with pumpsOnly water-displacing submersible pumps should be used. Pumps, which function according to the principle of air displacement, are not suitable. Fill up the sample vessel starting with the bottom, using a sampling tube, and discharge the water over an overflo

38、w. During sample transfer, the volume flow rate shall be controlled in order to guarantee a mainly laminar flow. Allow the water to overflow up to at least three times the volume of the vessel capacity.7.2 Measuring technique and precautions to be takenThe measuring system shall be in a proper state

39、 as outlined in the manufacturers instructions. For example: the sensor cap shall not be damaged; small scratches mostly do not matter (refer to manual); the system has to be calibrated when necessary (refer to manual).When a measurement is performed, ensure that the sample flows past the sensor cap

40、 with sufficient velocity to obtain a homogenous sample and a rapid reading. This can be achieved by natural streaming, movement of the sensor, or stirring e.g. with a magnetic stirrer (refer to manual).Take care that there is no exchange of oxygen from a gas reservoir to the sample or vice versa. T

41、herefore avoid formation of any air bubbles in the samples that are measured in a vessel. When measuring on-site, do not generate any air bubbles, as these can affect the signal.For storing and maintenance of the probe, consult the manufacturers manual. ISO 2014 All rights reserved 3BS ISO 17289:201

42、4ISO 17289:2014(E)7.3 Calibration7.3.1 GeneralThe procedure is described in 7.3.2 to 7.3.3, but it is also necessary to consult the manufacturers instructions.Calibration at air saturation should be checked daily and after relevant changes of ambient conditions (i.e. temperature or pressure).7.3.2 C

43、hecking the zeroIf necessary, check and, if possible, adjust the zero setting of the instrument by immersing the probe in 1 l of water to which the equivalent of 1 g or more sodium sulfite is added (5.2) (the solution is usable after adequate reaction time, when a stable reading is achieved). About

44、1 mg of cobalt(II) salt (5.3) can be added to increase the reaction rate. Alternatively, 100 ml of an alkaline ascorbic acid solution can be used. The alkaline ascorbic acid solution is prepared by dissolving 2 g ascorbic acid (5.4) and 25 ml 1 mol/l NaOH (5.5) in 85 ml deionised water in a suitable

45、 vessel with stopper (for total 110 ml volume). Start stirring slowly; wait 3 min before use. Use a reagent that is applicable for checking the zero according to the manufacturers manual.WARNING Water soluble cobalt(II) salts are toxic to humans and to aquatic life. Handling with care is necessary.N

46、OTE 1 Typical reaction times without cobalt(II) are 20 min, with cobalt(II) 5 min, and with alkaline ascorbic acid 30 min.The zero checking and setting, if possible, can also be performed by using a pure nitrogen (5.6) atmosphere.NOTE 2 Dry conditions are possible according to some manufacturers man

47、uals.Modern probes typically achieve a stable response within some minutes. However, different probes can have different response rates and the manufacturers instruction should be consulted. If stirring is required according to the manufacturers manual, carry out the stirring in such a way thata) th

48、e response time is minimized andb) no oxygen from the atmosphere is mixed in.7.3.3 Calibration at saturationPerform the calibration in an applicable container according to the manufacturers manual. Simple and effective calibration is possible in water vapour saturated air.Replace the sensor cap when

49、 the instrument can no longer be calibrated, when the meter software does not accept the sensor cap response, or when the response becomes unstable or slow (see the manufacturers instructions).NOTE Values can be checked by the Winkler titration (see ISO 5813).7.4 DeterminationCarry out the determination on the water to be analysed according to manufacturers instructions.Gently agitate the sample, e.g. by stirring (see 7.2), if recommended by the manufacturer. Check the influencing variables like sample temperature,