1、INTERNATIONAL STANDARD IS0 11041 First edition 1996-04-I 5 Workplace air - Determination of particulate arsenic and arsenic compounds and arsenic trioxide vapour - Method by hydride generation and atomic absorption spectrometry Air des lieux de travail - Dosage de /arsenic pat-ticulaire, des compos&
2、 particulaires de /arsenic et des vapeurs de trioxyde darsenic - M&hode par production dhydrures et spectrom&rie dabsorption atomique Reference number IS0 11041 :I 996(E) IS0 11041:1996(E) Foreword IS0 (the International Organization for Standardization) is a worldwide federation of national standar
3、ds 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 organi
4、zations, 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 cir
5、culated 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 11041 was prepared by Technical Committee ISO/TC 146, Air quality, Subcommittee SC 2, Workplace atmospheres. Annex A of
6、 this International Standard is for information only. Q IS0 1996 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
7、the publisher. International Organization for Standardization Case Postale 56 l CH-1211 Geneve 20 l Switzerland Printed in Switzerland ii INTERNATIONAL STANDARD 0 IS0 IS0 11041:1996(E) Workplace air - Determination of particulate arsenic and arsenic compounds and arsenic trioxide vapour - Method by
8、hydride generation and atomic absorption spectrometry WARNING - Arsenic and arsenic compounds are toxic and are recognized as human carcinogens (see reference 111 in annex A). Avoid any exposure by inhalation. Personal protection (e.g. an effective respirator) must be used in all cases where exposur
9、e to arsenic or arsenic compounds is possible. 1 Scope This International Standard specifies a method for the determination of the mass concentration of particulate arsenic and arsenic compounds and arsenic trioxide vapour in workplace air, using either continuous-flow hydride generation or flow-inj
10、ection-analysis hydride generation and atomic absorption spectrometry. The method is not suitable for determination of arsenic in the form of metal arsenides which decompose in the presence of water or acid (see 10.1). The method is applicable to the determination of masses of approximately 100 ng t
11、o 125 pg of arsenic per sample, for analysis of test solutions prepared using sample solution aliquots in the recommended range (see 9.3.2). The concentration range for arsenic in air, for which this procedure is applicable, is deter- mined in part by the sampling procedure selected by the user. The
12、 method is applicable to personal and fixed- location sampling. A number of transition metals may interfere with the determination of arsenic by hydride generation and atomic absorption spectrometry (see 10.3) this International Standard. At the time of publication, the editions indicated were valid
13、. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to in- vestigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and IS0 maintain registers of currently valid International St
14、andards. IS0 648:1977, Laboratory glassware - One-mark pipettes. IS0 1042:1983, Laboratory glassware - One-mark volumetric flasks. IS0 3585:1991, Borosilicate g/ass 3.3 - Properties. IS0 3696:1987, Water for analytical laboratory use - Specification and test methods. IS0 6955:1982, Analytical spectr
15、oscopic methods - Flame emission, atomic absorption and atomic fluorescence - Vocabulary. IS0 7708:1995, Air quality - Particle size fraction definitions for health-related sampling. IS0 8655-l :-I), Piston and/or plunger operated volumetric apparatus (POVA) - Part 1: Definitions. 2 Normative refere
16、nces The following standards contain provisions which, through reference in this text, constitute provisions of IS0 8655-2:-l), Piston and/or plunger operated volumetric apparatus (POVA) - Part2: Operating considerations. 1) To be published IS0 11041:1996(E) 0 IS0 IS0 8655-3:-l), Piston and/or plung
17、er operated volumetric apparatus (POVA) - Part3: Methods of test. IS0 8655-4:-l), Piston and/or plunger operated volumetric apparatus (POVA) - Part 4: Specifications. IS0 8756:1994, Air quality - Handling of tempera- ture, pressure and humidity data. EN 48211994, Workplace atmospheres - General requ
18、irements for the performance of procedures for the measurement of chemical agents. EN 482, CEN, Brussels, Belgium (1994). EN 1232:-l), Workplace atmospheres - Pumps for personal sampling of chemical agents - Require- men ts and test methods. 3 Principle 3.1 Particulate arsenic and arsenic compounds
19、and arsenic trioxide vapour are collected by drawing a measured volume of air through a cellulose ester membrane filter and a back-up paper pad impregnated with sodium carbonate and mounted in a sampler de- signed to collect the inhalable fraction of airborne par- ticles. 3.2 The cellulose ester mem
20、brane filter, back-up paper pad and collected sample are wet-ashed using nitric acid, sulfuric acid and hydrogen peroxide. The nitric acid and hydrogen peroxide are removed by boiling on a hotplate until dense, white fumes of sulfur trioxide are evolved, and the sample solution is then allowed to co
21、ol and diluted to a given volume with water. NOTE 1 The wet-ashing procedure specified in 8.2.2 is based upon a NIOSH procedure (see reference I21 in annex A) which has been modified to avoid taking the sample solution to dryness. 3.3 A test solution is prepared by transferring an aliquot of the sam
22、ple solution to a volumetric flask, together with appropriate volumes of dilute sulfuric acid, concentrated hydrochloric acid and potassium iodide solution, and diluting to volume with water. 3.4 The test solution is reacted with sodium tetra- hydroborate solution in a continuous-flow hydride genera
23、tion system or flow-injection-analysis hydride generation system to liberate arsine and hydrogen. These gaseous products are separated from the reaction liquid in a gas/liquid separator and carried by an inert purge gas into a silica or quartz absorption cell. This absorption cell is mounted in the
24、optical path of an atomic absorption spectrometer equipped with an arsenic hollow cathode lamp or electrodeless dis- charge lamp, and it is heated either electrically or by an oxidizing air/acetylene flame. NOTE 2 This international Standard describes the use of two types of hydride generation syste
25、m. Continuous flow systems function by pumping a continuous stream of test solution to the mixing piece, and such systems generate a constant atomic absorption signal. Flow injection analysis systems inject a discrete volume of test solution, and produce a transient atomic absorption signal. 3.5 Abs
26、orbance measurements are made at 197,2 nm or 193,7 nm, and results are obtained by the analytical-curve technique (see IS0 6955:1982, sub- clause 6.1 .l), or the analyte addition technique (see IS0 6955:1982, subclause 6.1.3). 4 Reactions 4.1 In most workplace situations where exposure to arsenic ca
27、n occur (e.g. in the refining of base metals, welding and other hot metal processes) a significant proportion of the arsenic is present in the form of arsenic trioxide vapour (see reference 131 in annex A). This vapour is collected by reaction with sodium carbonate on an impregnated back-up paper pa
28、d. As,O, + Na,CO, + 2NaAs0, + CO, 4.2 The majority of arsenic compounds which are commonly found in samples of workplace air are con- verted to soluble arsenate ions (AsO$-1 by the wet- ashing procedure specified in 8.2.2. However, if there is any doubt about the effectiveness of this procedure for
29、dissolution of particulate arsenic compounds which could be present in the test atmosphere, investigate before proceeding with the method (see 10.2). 4.3 Prior to hydride generation (see 4.4) arsenate ions (AsO,s-1 are reduced to arsenite ions (AsO,-) by reaction with potassium iodide (see 8.2.4). A
30、sO,s- + 2l- + 4H+ + AsO,- + I2 + 2H,O This reduction is necessary since pentavalent arsenic gives a lower analytical response than trivalent arsenic because it is less rapidly converted to arsine. 4.4 Hydride generation occurs as a result of the reaction between trivalent arsenic and nascent hydro-
31、gen produced by the action of hydrochloric acid on sodium tetrahydroborate solution. BH,- + H + 3HzO + H,BO, + 8H . . . (1) AsOz- + H+ + 6H + ASH, + 2H20 . . . (2) 1) To be published. Q IS0 IS0 11041:1996(E) 4.5 Arsenic atoms are produced from arsine by the action of heat in a silica or quartz absor
32、ption cell, heated either by a lean air/acetylene flame or elec- trically. 5 Reagents During the analysis, use only reagents of analytical grade, and only water as specified in 5.1. 5.1 Water, complying with the requirements for IS0 3696 grade 2 water (electrical conductivity less than 0,l mS/m and
33、resistivity greater than 0,Ol MSLm at 25 “C). 5.2 Sodium carbonate, 1 mol/l solution in 5 % WV) glycerol solution. Weigh IO,6 g of sodium carbonate (NazCOs) into a 250 ml beaker (6.2.1 .l). Add 5 ml of glycerol and 50 ml of water (5.1) and swirl to dissolve. Quantita- tively transfer the solution to
34、 a 100 ml one-mark volumetric flask (6.2.1.51, dilute to the mark with water, stopper and mix thoroughly. 5.3 Hydrochloric acid (HCI), concentrated P=- 1,18 g/ml, 35 % (m/m) to 36 % (m/m). The concentration of arsenic shall be less than 0,Ol ug/ml. WARNING - Concentrated hydrochloric acid is corrosi
35、ve, and hydrochloric acid vapour is irritant. Avoid exposure by contact with the skin or eyes, or by inhalation of fumes. Personal protective equipment (e.g. gloves, face shield or safety spec- tacles, etc.) must be used when working with the concentrated or diluted hydrochloric acid, and concentrat
36、ed hydrochloric acid must be used in a fume hood. The vapour pressure of hydrochloric is high, therefore beware of pressure build-up in stoppered flasks when preparing acid/water mixtures. 5.4 Hydrochloric acid, diluted 1 + 1. Pour approximately 900 ml of water (5.1) into a 2 000 ml one-mark volumet
37、ric flask (6.2.1.5). Carefully add 1 000 ml of concentrated hydrochloric acid (5.3) to the flask and swirl to mix. Allow to cool, dilute to the mark with water, stopper and mix thoroughly. NOTE 3 This is used as the solvent blank, as defined in IS0 6955:1982, subclause 5.4.2, but in this Internation
38、al Standard the solvent blank is referred to as the acid blank. 5.5 Hydrochloric acid, diluted 1 + 4. Pour approximately 700 ml of water (5.1) into a 1 000 ml one-mark volumetric flask (6.2.1.5). Carefully add 200 ml of concentrated hydrochloric acid (5.3) to the flask and swirl to mix. Allow to coo
39、l, dilute to the mark with water, stopper and mix thoroughly. 5.6 Nitric acid (HNOs), concentrated, P“ I,42 g/ml, 69 % (m/m) to 71 % (m/m). The concentration of arsenic shall be less than 0,Ol pg/ml. WARNING - Concentrated nitric acid is corrosive and oxidizing, and nitric acid fumes are irritant. A
40、void exposure by contact with the skin or eyes, or by inhalation of fumes. Personal protective equipment (e.g. gloves, face shield or safety spec- tacles, etc.) must be used when working with the concentrated or diluted nitric acid, and concen- trated nitric acid must be used in a fume hood. 5.7 Sul
41、furic acid (HzS041, concentrated, P = I,84 g/ml, about 98 % (m/m). The concentration of arsenic shall be less than 0,05 pg/ml. WARNING - Concentrated sulfuric acid is corros- ive and causes burns. Avoid exposure by contact with the skin or eyes. Personal protective equip- ment (e.g. gloves, face shi
42、eld or safety spectacles, etc.) must be used when working with the con- centrated or diluted sulfuric acid. Fumes produced by heating concentrated sulfuric acid are irritant, and this operation must therefore be carried out in a fume hood. Caution must be exercised if adding water to sulfuric acid,
43、since this reacts violently with water (acid/water mixtures must be prepared by adding acid to water). 5.8 Hydrogen peroxide (H2021, approximately 30 % (m/m) solution. The concentration of arsenic shall be less than 0.01 pg/ml. WARNING - Hydrogen peroxide is corrosive and oxidizing. Avoid exposure b
44、e contact with the skin or eyes. Personal protective equipment (e.g. gloves, face shield or safety spectacles, etc.) must be used when working with protective equipment hydrogen peroxide. 5.9 Potassium iodide, 100 g/l solution. Weigh IO,0 g of potassium iodide (KI) into a 250 ml beaker (6.2.1.1). Ad
45、d 50 ml of water (5.1) and swirl to dissolve. Quantitatively transfer the solution to a 100 ml one-mark volumetric flask (6.2.1.51, dilute to the mark with water, stopper and mix thoroughly. Prepare a fresh solution each month. 5.10 Sulfuric acid, diluted 1 + 9. Carefully add 25 ml of concentrated s
46、ulfuric acid (5.7) to 200 ml of water (5.1) in a 1 litre beaker. Swirl to mix, allow to cool and quantitatively transfer to a 250 ml one-mark volumetric flask (6.2.1.5). Dilute to the mark with water, stopper and mix thoroughly. 3 IS0 11041:1996(E) 5.11 Arsenic stock standard solution, correspond- i
47、ng to 1 000 mg of As per litre. ide (NaOH) pellets into a 1 litre beaker (6.2.1 .l). Add 200 ml of water (5.1) and swirl to mix. Quantitatively transfer the solution to a 1 000 ml one-mark volu- 5.11.1 Use a commercially available arsenic standard solution at a concentration of 1 000 mg/l. Observe t
48、he metric flask (6.2.1.5), filtering through a membrane manufacturers expiry date or recommended shelf-life. filter using a suction filtration apparatus (6.2.6). Dilute to the mark with water (5.1), stopper and mix thoroughly. Prepare a fresh solution daily. Alternatively, prepare an arsenic standar
49、d solution according to the procedure specified in 5.11.2. 5.11.2 Accurately weigh 1,320 g + 0,001 g of arsenic trioxide (As2031 into a 50 ml beaker (6.2.1 .l), add 10 ml of concentrated hydrochloric acid. (5.3), cover with a watch glass (6.2.1.2) and heat to approximately 150 “C on the hotplate (6.2.5) in a fume hood until dis- solution is complete. Remove the beaker from the hotplate, allow to cool, quantitatively transfer the sol- ution to a 1 000 ml one-mark volumetric flask (6.2.1.51, dilute to the mark with hydrochloric acid diluted 1 + 1 (5.41, stopper and mix thoroughly. This so
