1、 ISO 2013 Water quality Determination of selenium Part 1: Method using hydride generation atomic fluorescence spectrometry (HG-AFS) Qualit de leau Dosage du slnium Partie 1: Mthode par spectromtrie de fluorescence atomique gnration dhydrures (HG-AFS) TECHNICAL SPECIFICATION ISO/TS 17379-1 First edit
2、ion 2013-07-15 Reference number ISO/TS 17379-1:2013(E) ISO/TS 17379-1:2013(E)ii ISO 2013 All rights reserved COPYRIGHT PROTECTED DOCUMENT ISO 2013 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electro
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4、41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ISO/TS 17379-1:2013(E) ISO 2013 All rights reserved iii Contents Page Foreword iv Introduction v 1 Scope . 1 2 Normative references 1 3 Principle 2 4 Interferences 2 5 Reagents and standards 3 6 Ap
5、paratus . 6 7 Sampling and sample preparation 7 7.1 Sampling techniques 7 7.2 Pre-reduction . 7 8 Instrumental set-up 8 9 Procedure. 8 10 Calibration and data analysis 9 10.1 General requirements . 9 10.2 Calculation using the calibration curve . 9 11 Expression of results 9 12 Test report 10 Annex
6、A (informative) Additional information 11 Annex B (informative) Figures .12 Annex C (informative) Performance data .15 ISO/TS 17379-1:2013(E) Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of prep
7、aring 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-governmental, in
8、liaison with ISO, also take part in the work. ISO collaborates closely with the International 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
9、 Directives, Part 1. In particular the different approval criteria needed for the different types of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2, www.iso.org/directives. Attention is drawn to the possibility that s
10、ome 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. Details of any patent rights identified during the development of the standard will be in the Introduction and/or on the ISO list of patent decla
11、rations received, www.iso.org/patents. Any trade name used in this document is information given for the convenience of users of this document and does not constitute an endorsement. Equivalent products can be used if they can be shown to lead to the same results. The committee responsible for this
12、document is ISO/TC 147, Water quality, Subcommittee SC 2, Physical, chemical and biochemical methods. ISO/TS 17379 consists of the following parts, under the general title Water quality Determination of selenium: Part 1: Method using hydride generation atomic fluorescence spectrometry (HGAFS) Part 2
13、: Method using hydride generation atomic absorption spectrometry (HGAAS)iv ISO 2013 All rights reserved ISO/TS 17379-1:2013(E) Introduction This part of ISO/TS 17379 is intended for use by analysts experienced with the handling of trace elements at very low concentrations. Inorganic selenium normall
14、y occurs in two oxidation states; Se(VI) and Se(IV). It is essential to convert all selenium species to the Se(IV) state prior to generating the hydrides. Selenium(VI) does not form a hydride. In natural water sources, selenium compounds generally occur in very small quantities, typically less than
15、1 g/l. Higher concentrations can be found, e.g. in industrial waste water. Selenium occurs naturally in organic and inorganic compounds and can have oxidation states II, 0, IV, and VI. In order to fully decompose all of the selenium compounds, a digestion procedure is necessary. Digestion can only b
16、e omitted if it is certain that the selenium in the sample can form a covalent hydride without the necessity of a pre-oxidation digestion step. The user should be aware that particular problems could require the specification of additional marginal conditions. ISO 2013 All rights reserved v Water qu
17、ality Determination of selenium Part 1: Method using hydride generation atomic fluorescence spectrometry (HG-AFS) 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, associated with its
18、use. It is the responsibility of 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 document be carried out by suitably trained and experienc
19、ed staff. 1 Scope This part of ISO/TS 17379 specifies a method for the determination of selenium. The method is applicable to drinking water, surface water, ground water, and rain water. The application range of this part of ISO/TS 17379 is from 0,02 g/l to 100 g/l. Samples containing selenium at hi
20、gher concentrations than the application range can be analysed following appropriate dilution. The method is unlikely to detect organoselenium compounds. The sensitivity of this method is dependent on the operating conditions selected. 2 Normative references The following documents, in whole or in p
21、art, are normatively referenced in this document and are indispensable for its application. 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 laboratory use Sp
22、ecification and test methods ISO 5667-1, Water quality Sampling Part 1: Guidance on the design of sampling programmes and sampling techniques ISO 5667-3, Water quality Sampling Part 3: Preservation and handling of water samples ISO 5667-5, Water quality Sampling Part 5: Guidance on sampling of drink
23、ing water from treatment works and piped distribution systems ISO 5667-6, Water quality Sampling Part 6: Guidance on sampling of rivers and streams ISO 5667-8, Water quality Sampling Part 8: Guidance on the sampling of wet deposition ISO 5667-11, Water quality Sampling Part 11: Guidance on sampling
24、of groundwaters 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 15587-1, Water quality Digestion for the determination of selected elements in water Part 1:
25、Aqua regia digestion TECHNICAL SPECIFICATION ISO/TS 17379-1:2013(E) ISO 2013 All rights reserved 1 ISO/TS 17379-1:2013(E) 3 Principle An aliquot of sample is treated with concentrated hydrochloric acid (5.2). Se(VI) is pre-reduced to Se(IV) by gently refluxing in 6 mol/l HCl for 1 h. Care is necessa
26、ry to avoid any losses of volatile selenium components. A suitable apparatus is shown in Figure B.3. The sample solutions are then treated with sodium tetrahydroborate to generate the covalent gaseous hydride (SeH 2 ). The hydride and excess hydrogen are swept out of the generation vessel in the bat
27、ch mode and out of the gas/liquid separator in the the continuous mode into an atomizer suited for atomic fluorescence measurements (e.g. a chemically generated hydrogen diffusion flame). The hydride is atomized and the resulting atoms excited by an intense selenium light source, the resulting fluor
28、escence is detected by atomic fluorescence spectrometry after isolation by an interference filter that transmits the selenium fluorescence at a wavelength, = 196,0 nm. The procedure is automated by means of an auto sampler and control software. 4 Interferences The hydride generation technique is pro
29、ne to interferences by transition and easily reducible metals. For the majority of natural water samples, this type of interference should not be significant. The user should carry out recovery tests on typical waters and also determine the maximum concentrations of potentially interfering elements,
30、 using appropriate methods. If such interferences are indicated, the level of interferences should be assessed by performing spike recoveries. However, the atomic fluorescence technique has a high linear dynamic range and a very low detection limit. In most cases, any interferences can be removed by
31、 a simple dilution step. The reaction conditions set out in this part of ISO/TS 17379 have been chosen so that any interferences are reduced to a minimum. It is important that the light source does not contain any significant amount of other hydride-forming elements (e.g. arsenic, antimony, telluriu
32、m) that emit fluorescent radiation over the bandpass of the interference filter used in the detector, if these elements are present in the sample. Measurements carried out using the procedures in this part of ISO/TS 17379 do not generally suffer from interferences due to quenching within the ranges
33、of interest. Interference studies on a number of elements have been conducted and are shown in Table 1. It can be seen that tellurium causes a significant positive bias and that gold, silver and copper cause a significant negative bias. However, these elements are unlikely to be present at the teste
34、d levels in the vast majority of water samples. Interferences can be indicated by the irregularity of the signal peak shape. Usually the interference can be removed by diluting the samples, this dilution should not reduce the concentration of the analyte lower than the limit of quantification. Table
35、 1 Interference study for selenium Interfering substance Concentration of interfering sub- stance Se recovery mg/l 2 g/l Se 10 g/l Se Thallium nitrate Tl(Ill) 20 98,4 3,1 97,2 1,6 Strontium nitrate Sr(II) 20 101,6 1,2 97,0 1,5 Zinc nitrate Zn(II) 1 99,9 1,8 102,4 0,8 Diammonium silicon hexafluoride
36、Si(IV) 1 96,7 2,7 98,8 1,82 Aluminium nitrate Al(III) 1 95,2 3,0 97,2 0,5 Calcium chloride Ca(II) 200 97,4 0,9 97,0 3,3 Sodium chloride Na(I) 200 98,0 1,0 95,0 0,62 ISO 2013 All rights reserved ISO/TS 17379-1:2013(E) Interfering substance Concentration of interfering sub- stance Se recovery mg/l 2 g
37、/l Se 10 g/l Se Potassium bromide K(I) 200 94,9 3,8 99,6 1,1 Indium nitrate In(III) 1 93,3 1,7 98,9 2,0 Barium nitrate Ba(II) 1 96,6 1,5 96,6 1,6 Magnesium oxide Mg(II) 1 98,9 2,4 97,0 0,9 Cadmium nitrate Cd(II) 1 99,4 0,5 90,1 0,9 Ammonium dihydrogenphosphate P(V) 1 98,0 1,9 96,9 3,4 Sodium fluorid
38、e F(I) 1 97,4 1,1 97,8 2,7 Gold chloride Au(Ill) 0,1 89,3 3,1 83,1 5,4 Gold chloride Au(llI) 1 46,2 4,1 76,8 6,4 Ortho-boric acid B(III) 1 99,1 1,9 101,4 2,1 Iron(II) nitrate Fe(II) 1 96,9 2,7 97,4 4,9 Lead(II) nitrate Pb(II) 1 99,2 2,5 97,9 0,9 Bismuth nitrate Bi(III) 1 105,0 4,8 95,6 1,7 Tin nitra
39、te Sn(IV) 1 93,8 6,1 97,8 1,5 Ammonium molybdate Mo(II) 1 95,7 2,3 97,0 1,3 Germanium chloride Ge(IV) 1 100,7 3,1 98,0 0,6 Mercury nitrate Hg(II) 1 99,4 3,7 99,7 3,9 Arsenic(III) oxide As(III) 1 99,4 2,5 97,7 7,3 Chromium(III) nitrate Cr(III) 1 95,9 2,0 98,6 1,5 Cobalt nitrate Co(II) 1 93,2 1,6 97,4
40、 1,7 Silver nitrate Ag(I) 1 78,2 6,5 72,0 0,8 Nickel(II) nitrate Ni(II) 1 95,0 3,6 97,1 1,9 Telluric acid Te(IV ) 0,01 104,0 1,8 98,8 1,8 Telluric acid Te(IV ) 0,1 110,0 5,0 105,2 1,0 Telluric acid Te(IV ) 1 123,5 0,5 108,6 1,0 Antimony oxide Sb(III) 0,01 98,6 0,8 99,1 0,3 Antimony oxide Sb(III) 0,0
41、5 89,3 3,1 98,5 2,1 Antimony oxide Sb(III) 0,1 95,8 2,2 100,4 1,1 Copper sulfate Cu(II) 0,1 98,5 1,5 96,4 0,0 Copper sulfate Cu(II) 0,2 93,4 1,9 100,8 2,5 Copper sulfate Cu(II) 0,5 94,5 0,5 98,3 1,9 Copper sulfate Cu(II) 1 82,2 2,3 85,1 5,4 Copper sulfate Cu(II) 2 79,8 2,4 98,8 1,8 Gold chloride Au(
42、I) 0,1 89,3 3,1 83,1 5,4 5 Reagents and standards During the analysis, unless otherwise stated, use only reagents of recognized analytical grade.Table 1 (continued) ISO 2013 All rights reserved 3 ISO/TS 17379-1:2013(E) Reagents may contain selenium as an impurity. All reagents should have selenium c
43、oncentrations below that which would result in a selenium blank value for the method being above the lowest level of interest. 5.1 Water, complying with grade 1 as defined in ISO 3696, for all sample preparation and dilutions. 5.2 Hydrochloric acid, (HCl) = 1,16 g/ml. 5.3 Hydrochloric acid, c(HCl) =
44、 1 mol/l. 5.4 Sodium tetrahydroborate, NaBH 4 , available as pellets. 5.5 Sodium hydroxide, NaOH. 5.6 Sodium tetrahydroborate solution, (NaBH 4 ) = 13 g/l. Prepare appropriate quantities on day of use (13 g/l has proven suitable for the system illustrated in Annex B) and do not keep in a closed cont
45、ainer because of pressure build-up due to hydrogen evolution. NOTE 1 The concentration of NaBH 4is dependent on the hydride generator manifold and flow rate conditions. See recommendations of the manufacturer. NOTE 2 Suitably stored sodium tetrahydroborate pellets have a shelf-life of 6 months. NOTE
46、 3 See Clause 8. 5.7 Nitric acid, (HNO 3 ) = 1,40 g/ml. NOTE Nitric acid is available both as (HNO 3 ) = 1,40 g/ml w(HNO 3 ) = 650 g/kg and (HNO 3 ) = 1,42 g/ml w(HNO 3 ) = 690 g/kg. Prepare a nitric acid cleaning mixture by diluting nitric acid (HNO 3 ) = 1,40 g/ml with an equal volume of water (5.
47、1) by carefully adding the acid to the water. 5.8 Reagent blank. For each 1 000 ml, prepare a solution containing (300 3) ml of hydrochloric acid (5.2). Dilute to volume with water (5.1). On the continuous flow system, the reagent blank solution is run as background. Since the blank solution may con
48、tain detectable trace levels of selenium, it is important that the same reagents be used for both sample and standard preparation, as well as for preparation of the reagent blank. The analyte signal is superimposed on this signal once the sample is introduced into the measurement cycle. The selenium
49、 concentration of the blank solution should be less than the lower level of interest. 5.9 Selenium standard solutions. 5.9.1 Selenium stock solution A, Se(IV) = 1 000 mg/l. Use a quantitative stock solution with a traceable Se(IV) content of (1 000 2) mg/l. This solution is considered to be stable for
