EN ISO 12020:2000

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.WURPHWULMVNDWasserbeschaffenheit - Bestimmung von Aluminium - Verfahren mittels Atomabsorptionsspektrometrie (ISO 12020:1997)Qualité de l'eau - Dosage de l'aluminium - Méthodes par spectrométrie d'absorption atomique (ISO 12020:1997)Water quality - Determination of aluminium - Atomic absorption spectrometric methods (ISO 12020:1997)13.060.50VQRYLExamination of water for chemical substancesICS:Ta slovenski standard je istoveten z:EN ISO 12020:2000SIST EN ISO 12020:2000en01-december-2000SIST EN ISO 12020:2000SLOVENSKI
STANDARDSIST ISO 12020:19981DGRPHãþD

INTERNATIONAL STANDARD IS0 12020 First edition 1997-03-O 1 Water quality - Determination of aluminium - Atomic absorption spectrometric methods Qualit6 de I’eau - Dosage de I’aluminium - M&hodes par spectromk trie d’absorption atomique Reference number IS0 12020: 1997(E) SIST EN ISO 12020:2000

IS0 12020:1997(E) Foreword IS0 (the international Organization for Standardization) is a worldwide federation of national standards bodies (IS0 member bodies). The work of preparing 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 liaison with ISO, also take part in the work. IS0 collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. 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 vote. International Standard IS0 12020 was prepared by Technical Committee lSO/TC 147, Water Quality, Subcommittee SC 2, Physical, chemical and biochemical methods. Annexes A and B of this International Standard are for information only. 0 IS0 1997 All rights reserved. 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 the publisher. International Organization for Standardization Case postale 56 l CH-1211 Geneve 20 l Switzerland Internet central @ iso.ch x.400 c=ch; a=40Onet; p=iso; o=isocs; s=central Printed in Switzerland ii SIST EN ISO 12020:2000

0 IS0 IS0 12020: 1997(E) Introduction Aluminium may be present in water in ionic or complex form. It may be dissolved or finely dispersed. Even with the digestion described in 2.5.3, silicates and oxidic aluminium compounds may not in all cases be quantitatively covered by these methods. Clause 2 refers to the determination of aluminium by flame atomic absorption spectrometty (AAS); in clause 3 a graphite furnace AAS method is described. SIST EN ISO 12020:2000

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INTERNATIONAL STANDARD o IS0 IS0 12020:1997(E) Water quality - Determination of aluminium - Atomic absorption spectrometric methods 1 Scope This International Standard describes two atomic absorption spectrometric (AAS) methods for the determination of aluminium in water. 1.1 Flame AAS The flame AAS method (clause 2) is applicable for the determination of aluminium in water in mass concentrations from 5 mg/l to 100 mg/l. Higher concentrations may be determined after an appropriate dilution of the sample. Careful evaporation of the sample, acidified with nitric acid, may be used to extend the working range of the method to lower concentrations as long as no precipitation is observed. NOTE - If the linear range of the instrument is sufficiently large, concentrations < 5 mg/l may be determined with this method; otherwise the determination needs to be carried out in the graphite furnace, as described in clause 3. If the determination of the total content of aluminium is required, a digestion of the sample according to 2.5.3 is necessary. Silicates and aluminium oxide compounds may, however, not be quantitatively determined with this digestion procedure. 1.2 Graphite furnace The graphite furnace AAS method (clause 3) is applicable for the determination of aluminium in waters and waste waters in mass concentrations from 10 pg/l to 100 pg/l applying a dosing volume of 20 ~1. The working range can be shifted to higher concentrations either by dilution of the sample or by using a smaller sample volume. 2 Determination of aluminium by atomic absorption spectrometry in a nitrous oxide/acetylene flame 2.1 Interferences The following ions can interfere with the flame AAS method, if the concentrations listed below are exceeded: Sulfate 10 000 mg/l Chloride 10 000 mg/l Phosphate I 10 000 mg/l I Sodium I 10 000 mg/l I Potassium I 10 000 mg/l 1 Magnesium Calcium 10 000 mg/l 10 000 mg/l Iron Nickel 10 000 mg/l 10 000 mg/l Cobalt I 10 000 mg/l -1 Cadmium I 3 000 mg/l I Lead 10 000 mg/l SIST EN ISO 12020:2000

IS0 12020: 1997(E) 0 IS0 Silicate 200 mg/l Fluoroborate Titanium 2 000 mg/l 1 000 mg/l Fluoride I 3 000 mg/lV I 1) This concentration is applicable for strongly acidic samples or measuring solutions with pH c 1. In less acidic solutions precipitation may occur. The total salt content of the measuring solution should not exceed 15 g/l, or its electrical conductivity should not be higher than 2 000 mS/m. For samples whose matrix influence is unknown, the conductivity should be investigated and compensated for, if possible, for example by dilution of the sample or by application of the method of standard additions. 2.2 Principle Acid is added to the water sample which is then aspirated into a nitrous oxide/acetylene flame of an atomic absorption spectrometer. The absorbance is measured at a wavelength of 309,3 nm and the aluminium content calculated. 2.3 Reagents 2.3.1 General requirements Use only reagents of at least recognized analytical grade quality and double-distilled water or water of equivalent purity. The aluminium content of the water or the reagents used shall be negligibly low, compared with the lowest concentration of aluminium to be determined. 2.3.2 Hydrochloric acid, &Cl = 1 ,I6 g/ml. 2.3.3 Nitric acid, PHNo~ = I,40 g/d 2.3.4 Hydrogen peroxide (dihydrogen dioxide), WH202 = 30 %. 2.3.5 Caesium chloride solution, pcs = 20 g/l. Dissolve 25,3 g of CsCl in 100 ml of HCI (2.3.2) and make up to 1 000 ml with water (2.3.1). 2.3.6 Aluminium stock solution, PAI = 1 000 mg/l. Dissolve 1,000 g of aluminium, minimum purity 99,9 % or band, in a graduated flask, nominal capacity 1 000 ml, in approximately 15 ml of hydrochloric acid (2.3.2) and make up to volume with water (2.3.1). Alternatively, prepare the solution with a commercially available aluminium standard which contains (1,000 +, 0,002) g Al. 2.3.7 Aluminium standard solution, PAI = 100 mg/l. Pipette 100 ml of the aluminium stock solution (2.3.6) into a 1 OOO-ml graduated flask, add 10 ml of nitric acid (2.3.3), and make up to volume with water (2.3.1). 2.3.8 Aluminium calibration solutions. In accordance with the aluminium concentration expected in the sample, prepare at least five calibration solutions from the aluminium standard solution (2.3.7). For the working range of 5 mg/l to 50 mg/l, proceed, for example, as follows. a) Pipette, into a series of IOO-ml graduated flasks, 5 ml, 10 ml, 20 ml, 30 ml and 50 ml of the aluminium standard solution (2.3.7); 2 SIST EN ISO 12020:2000

0 IS0 IS0 12020:1997(E) b) add 2 ml of caesium chloride solution (2.3.5); c) acidify each of these solutions with 1 ml of nitric acid (2.3.3); d) make up to volume with water and mix. The calibration solutions contain 5 mg/l, 10 mg/l, 20 mg/l, 30 mg/l or 50 mg/l of aluminium, respectively. Prepare the calibration solutions on the day of use. NOTE - It is advantageous to use additional calibration solutions in the main part of the working range. 2.3.9 Blank solution. Pipette 1 ml of nitric acid (2.3.3) into a IOO-ml graduated flask, and make up to volume with water. If the sample is to be digested or evaporated to a smaller volume, the blank solution shall be submitted to the same pretreatment (2.53). 2.3.10 Zeroing solution. Use water (2.3.1) as zeroing solution. The blank solution (2.3.9) may also be used to zero the instrument, provided the aluminium content of the blank solution is negligibly low. The zeroing solutions shall not be stored in bottles made of polyolefins (see 2.5.1). 2.4 Apparatus 2.4.1 Atomic absorption spectrometer, with background correction and radiation source for the determination of aluminium. 2.4.2 Gas supply with nitrous oxide and acetylene; the residual pressure of the acetylene tanks shall never fall below 500 kPa. The nitrous oxide/acetylene supply should be designed to allow high supply quantities. 2.4.3 Graduated flasks, nominal capacities IO ml, 100 ml and 1 000 ml. 2.4.4 One-mark pipettes, nominal capacities 5 ml, IO ml, 20 ml, 30 ml and 50 ml. 2.4.5 Microlitre pipette or diluter. 2.4.6 Silica glass beaker, nominal capacity 250 ml. 2.4.7 Heating appliance, e.g. electric heating plate. 2.4.8 Membrane filtration device, with membrane filters of pore size 0,45 Frn. 2.5 Sampling and sample preparation 2.5.1 General requirements Clean the glassware immediately before use with warm dilute nitric acid, c(HN0,) = 0,2 mol/l, and thoroughly rinse with water (2.3.1). Check incoming batches of pipette tips and one-way vessels for possible aluminium contamination. Collect the samples in bottles made of an appropriate plastics material. Bottles made of polyolefins shall not be used because they may contain traces of aluminium. Clean the sample containers as specified for glassware. SIST EN ISO 12020:2000

0 IS0 IS0 12020: 1997(E) 2.5.2 Pretreatment for the determination of dissolved aluminium a) Filter the water sample as soon as possible after sample collection (2.5.1) through a membrane filter, pore size 0,45 pm. b) Acidify the filtrate with 1 ml of nitric acid (2.3.3) per 1 000 ml of water sample for stabilization. C) The resulting pH shall be < 2, otherwise add more acid. 2.5.3 Pretreatment for the digestion procedure a) Immediately after sample collection, add 1 ml of nitric acid (2.3.3) per 1 000 ml of sample. b) The resulting pH shall be < 2, otherwise add more acid. ) In a silica glass beaker add 1 ml of nitric acid (2.3.3) and 1 ml of hydrogen peroxide (2.3.4) to 100 ml of the homogenized sample and evaporate to a moist residue. To prevent losses, do not evaporate the water sample to complete dryness. ) Take up the moist residue with 1 ml of nitric acid (2.3.3) and a small quantity of water (2.3.1), and make up to 100 ml. Treat the blanks in the same way. 2.5.4 Preparation of the measuring solution a) Place 20 ml of the water sample, pretreated as described in 2.5.2 or 2.5.3, in a 25-ml graduated flask. Add 2 ml of caesium chloride solution (2.3.5), mix well and make up to volume with water (2.3.1). b) Treat the blank solution and the calibration solutions in exactly the same way. 2.6 Procedure a) Prior to the measurement, set the operating parameters of the atomic absorption spectrometer in accordance with the manufacturer’s operating manual. b) Zero the instrument by aspirating the zeroing solution (2.
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