SANS 10566-2006 Water quality - Determination of aluminium - Spectrometric method using pyrocatechol violet《水质 铝的测定 邻苯二酚紫光度法》.pdf

1、 Collection of SANS standards in electronic format (PDF) 1. Copyright This standard is available to staff members of companies that have subscribed to the complete collection of SANS standards in accordance with a formal copyright agreement. This document may reside on a CENTRAL FILE SERVER or INTRA

2、NET SYSTEM only. Unless specific permission has been granted, this document MAY NOT be sent or given to staff members from other companies or organizations. Doing so would constitute a VIOLATION of SABS copyright rules. 2. Indemnity The South African Bureau of Standards accepts no liability for any

3、damage whatsoever than may result from the use of this material or the information contain therein, irrespective of the cause and quantum thereof. ISBN 0-626-18552-1 SANS 10566:2006Edition 1 ISO 10566:1994Edition 1SOUTH AFRICAN NATIONAL STANDARD Water quality Determination of aluminium Spectrometric

4、 method using pyrocatechol violet This national standard is the identical implementation of ISO 10566:1994 and is adopted with the permission of the International Organization for Standardization. Published by Standards South Africa 1 dr lategan road groenkloof private bag x191 pretoria 0001 tel: 01

5、2 428 7911 fax: 012 344 1568 international code + 27 12 www.stansa.co.za Standards South Africa SANS 10566:2006 Edition 1 ISO 10566:1994 Edition 1 Table of changes Change No. Date Scope National foreword This South African standard was approved by National Committee StanSA SC 5140.19A, Water Water s

6、ampling and analysis, in accordance with procedures of Standards South Africa, in compliance with annex 3 of the WTO/TBT agreement. INTERNATIONAL STANDARD IS0 10566 First edition 1994-12-15 Water quality - Determination of aluminium - Spectrometric method using pyrocatechol violet Qua/it6 de Ieau -

7、Dosage de Ialuminium - Mgthode par spectromtrie ;i /aide du violet de pyrocatbchol Reference number IS0 10566:1994(E) IS0 10566:1994(E) Foreword IS0 (the International Organization for Standardization) is a worldwide federation of national standards bodies (IS0 member bodies). The work of preparing

8、International Standards is normally carried out through IS0 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 liaiso

9、n with ISO, also take part in the work. IS0 collaborates closely with the International Electrotechnical Commission (I EC) on all matters of electrotechnical standardization. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication

10、 as an International Standard requires approval by at least 75 % of the member bodies casting a vote. International Standard IS0 10566 was prepared by Technical Committee lSO/TC 147, Water quality, Subcommittee SC 2, Physical, chemical, biochemical methods. 0 IS0 1994 All rights reserved. Unless oth

11、erwise 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 the publisher. Intern ational Organization for Standardization Case Postale 56 l CH-121 1 Geneve

12、 20 l Switz Printed in Switzerland 0 IS0 IS0 10566:1994(E) Introduction Aluminium occurs in a variety of types of compounds in nature, and can be found in acid, neutral and alkaline solutions. It can also form colloidal polymeric solutions and gels, as well as flocculant precipitates, all based on a

13、quated positive ions or hydroxylated aluminates. In as addition, fluoride, it can form chloride and complexes with organic sulfate, most but not all aci of ds and which with ions such are soluble. Aluminium can also form lattice compounds with oxygen (and hydroxyl species), silicon, and some metals.

14、 Although insoluble, some of these compounds, notably the clays, micas and zeolites, can be found as fine suspended particles in rivers. Although they contain aluminium, these in- soluble lattice compounds are not usually considered as aluminium com- pounds in the context of the water cycle. The met

15、hod described in this International Standard is restricted to the determination of the aquated cations and other forms of aluminium readily converted to that cationic form by acidification. The pretreatment with nitric acids is identical to that described in other International Standards using spect

16、rometric methods with an electrothermal atomization or in- ductively coupled plasma procedure (methods of preparation). This page intentionally left blank INTERNATIONAL STANDARD 0 ISO IS0 10566:1994(E) Water quality - Determination of aluminium - Spectrometric method using pyrocatechol violet 1 Scop

17、e 1.1 Type of sample The method is applicable to the analysis of potable waters, ground waters, and lightly polluted surface and sea waters. 1.2 Substance determined The method determines filterable (dissolved) and acid-soluble aluminium. 1.3 Range The method includes low range determination up to 1

18、00 pg/l Al with 50 mm cells and high range determi- nation up to 500 pg/l Al with 10 mm cells. The effec- tive range depends on the sensitivity of the spectrometer and can be extended upwards by taking smaller test portions. 1.4 Limit of detection The limit of detection is 2 pg/l when cells of optic

19、al path length 50 mm and a 25 ml test portion are used. 1.5 Sensitivity An aluminium concentration of 100 pg/l gives an absorbance of about 0,20 + 0,05 optical absorption units, using a 25 ml test portion and cells of optical path length 10 mm. 1.6 Precision If not specified, the precision of volume

20、s and masses mentioned in this International Standard is + 1 % of - the value. 2 Normative reference The following standard contains provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publi- cation, the edition indicated was valid.

21、All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most re- cent edition of the standard indicated below. Mem- bers of IEC and IS0 maintain registers of currently valid International Stan

22、dards. IS0 5667-3: 1994, Water quality - Sampling - Part 3: Guidance on the preservation and handling of samples. 3 Principle For dissolved aluminium, the sample is filtered through membrane filters with 0,45 pm pore size and then acidified with nitric acid to obtain a pH of I,2 to 15 I l For acid-s

23、oluble aluminium, the untreated sample is acidified with nitric acid to obtain a pH of I,2 to 1,5, kept for at least 1 h at room temperature to dissolve the aluminium and then filtered. Aluminium is reacted with pyrocatechol violet at a pH of 5,9 +_ 0,l followed by spectrometric measurement of the r

24、esulting coloured complex at a wavelength of 580 nm (the blue colour is visible only at high alu- minium concentrations). NOTE 1 For other kinds of determination, e.g. digestions, the sample is pretreated accordingly, using nitric acid at a pH of I,2 to I,5 in the final sample. IS0 10566:1994(E) 0 I

25、S0 4 Reagents 4.6 Hexamine buffer solution Use only reagents of recognized analytical grade. En- sure that the aluminium content is negligible com- bared with the smallest concentration to be Dissolve 210 g hexamethylene-tetramine (C6H12N4) in approximately 200 ml of water (4.2). Transfer the sol- u

26、tion to a 500 ml one-mark volumetric flask and make I determined in the samples. up to the mark with water. All reagent solutions shall be free of suspended par- titles (dust) which can interfere with spectrometry. If necessary, filter through a membrane filter of pore size 0,45 pm. Solutions shall

27、be stored in closed plastics laboratory bottles at room temperature, preferably not exposed to bright light. This solution is stable for at least 2 months. NOTE 4 This solution is close to saturation. It should be kept above 15 “C to prevent crystallization. Some brands of hexamine contain dust part

28、icles, in which case the buffer should be filtered after preparation. 4.7 Aluminium stock solution, 1 000 mg/l. 4.1 Nitric acid (HNO$, p = I,40 g/ml, 65 % (V/v). Weigh 100 mg of aluminium foil to a precision of + 0,5 mg. Dissolve the aluminium in a 100 ml one- - mark volumetric flask, using 1 ml of

29、nitric acid (4.1) and a few millilitres of water (4.2). When dissolution is complete, make up to the mark with water. NOTE 5 Commercially available aluminium standard sol- utions may be used. 4.2 Distilled or deionized water which is free from aluminium, i.e. aluminium content below 1 pg/l or below

30、1 % of the range of determination. 4.3 Acidified water Add 4,0 ml of nitric acid (4.1) to 1 000 ml of water (4.2). The solution is stable at room temperature, unless no loss from evaporation occurs. 4.4 Mixed reagent 4.8 Aluminium standard solution, 10 mg/l. Add 1 ,O ml of nitric acid (4.1) to appro

31、ximately 70 ml of water (4.2) in a 200 ml plastics laboratory beaker (5.3). To this solution, add 25,0 g of magnesium sul- fate heptahydrate MgSO,.7H,O, 5,0 g of ascorbic acid (C,H,O,), 0,25 g of 1 ,I 0-phenanthroline monohy- drate C,HsNZ.H,O and 5,0 ml of aluminium standard solution (4.8). Transfer

32、 to a 100 ml one-mark volumetric flask and make up to the mark with water. This solution is stable for one month. Pipette I,00 ml of aluminium stock solution (4.7) into a 100 ml one-mark volumetric flask and make up to the mark with acidified water (4.3). 4.9 Sodium hydrogen carbonate, 2,0 mol/l sol

33、- ution. Dissolve 85 g of sodium hydrogen carbonate (NaHCO,) in about 400 ml of water. Transfer the sol- ution to a 500 ml one-mark volumetric flask and make NOTE 2 Accurate addition of the aluminium standard solution is essential in order to allow a linear calibration at low concentrations. 4.5 Pyr

34、ocatechol violet solution up to the mark with water (4.2). Carefully dissolve 0,050 g of pyrocatechol violet (C, the aluminium content should be below 2 Fg/l. Reserve the plastics ware and optical cells, if possible, solely for aluminium determinations. Re- move all residual aluminium from previous

35、determi- nations by cleaning all plastics ware and optical cells by filling with, or soaking in, acidified water (4.3) overnight. Do not use detergent or chromic acid. 5.6 pH-metre. 5.7 Microlitre pipettes, with disposable tips. 6 Sampling and samples See IS0 5667-3. Collect samples in polyethylene

36、bottles. Clean the sample bottles and filtration device according to the procedure described in clause 5. 6.1 Filtrable aluminium Immediately after sampling, filter the sample through a membrane filter (5.2). Acidify the filtrate by adding 0,30 ml of nitric acid (4.1) per 100 ml of sample. 6.2 Acid-

37、soluble aluminium Add 0,30 ml of nitric acid (4.1) per 100 ml of sample. The pH shall be I,2 to 1,5, if not, add more acid. Store for at least 1 h at room temperature and filter the sample through a membrane filter (5.2). For special purposes other pretreatment procedures may be used (see clause 7).

38、 NOTE 8 Failure of proper acidification of the sample leads to incorrect results because the pH during reaction and The most important interference with micro- determinations of aluminium is the release of alu- minium from the surface of the vessels used for sampling and handling. In particular, alu

39、minium is easily leached from most items of glassware. Thus, glassware shall not be used for aluminium determi- nations in the range below 50 pg/l Al. It is strongly recommended to use only plastics laboratory ware pretreated as described in clause 5. Fluoride ions form stable complexes with alumini

40、um, thus preventing the formation of the aluminium- pyrocatechol violet complex. The resulting negative bias interferes especially at low aluminium concen- trations. This effect is almost totally eliminated by the addition of magnesium ions (see 4.4) which form relatively strong complexes with fluor

41、ide. Iron forms a coloured complex with pyrocatechol vio- let. Interference effects caused by iron are minimized by reduction to the ferrous state followed by com- plexing with I,1 0-phenanthroline. This iron complex gives rise to a very small absorbance at 580 nm. I,0 mg/l of iron is equivalent to

42、0,05 pg/l of alu- minium. Coloured compounds, inorganic as well as organic, that give an absorbance at 580 nm generally interfere with this determination, when absorbance exceeds 0,050 cm- I. An oxidative digestion can destroy the coloured species and allow proper determination. Humic substances and

43、 other organic compounds with complexing properties can interfere. Interference is evident when addition of aluminium to the sample gives a smaller increase in absorbance than expected for that additional amount. This kind of interference is eliminated by digestion with H,O, and HNO,. 8 Procedure De

44、pending on the cell path length and sensitivity of the spectrometer, the procedure comprises two ranges: a low level range up to 100 pg/l Al with 50 mm cells; a high level range up to 500 pg/l Al with 10 mm cells. IS0 10566:1994(E) 0 IS0 of each ac idif ied n at a wavelength (4.3) as a reference of

45、580 nm against 8.1 Test portions water Take a test portion volume of 25 ml from samples 6.1 or 6.2. In order to accommodate higher aluminium concentrations, use smaller test portions and adjust the volume to 25 ml by the addition of acidified water (4.3) and note the dilution factorf (see clause 9).

46、 Use cells of an optical path length that is appropriate and sensitivity. for the selected range Measure of the sa the blan k and standard solutions with cells me size. 8.2 Calibration solutions Read the absorbance A, of each standard of sample. 8.2.1 Preparation of high range calibration solutions

47、(e.g. 500 pg/l Al with 10 mm cells) 8.5 Plotting the calibration graph Pipette 0 ml (blank), I,00 ml, 2,00 ml, 3,00 ml, 4,00 ml and 5,00 ml respectively of the aluminium standard solution (4.8) into a series of 100 ml one- mark volumetric flasks (5.4). Make up to the mark with acidified water (4.3).

48、 These solutions contain 0 pg/l (blank), 100 pg/l, 200 pg/l, 300 pg/l, 400 pg/l and 500 pg/l Al respectively. Plot a calibration graph with the mass concentrations of aluminium PAI on the abscissa and the correspond- ing absorbance A, of the standards on the ordinate. The slope of the calibration cu

49、rve is a measure of the sensitivity of the method, in litres per milligram. The intersection with the ordinate is the absorbance of the sample (calculated blank) without the addition of alu- minium in the standard solution. 8.2.2 Preparation of low range calibration solutions (e.g. 50 pg/l Al with 50 mm cells) The blank and the slope shall be checked from time to time, in accordance with good analytical quality control practice, especially when new batches of re- agents are used. Pipette, for example, 0 ml (blank), 100 J.LI, 200 1, 300 1, 400 1 and 500 JLI respectively of