ISO-11212-3-1997.pdf
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1、STD-IS0 LL212-3-ENGL 1997 M 4851903 0703571 233 INTERNATIONAL STANDARD IS0 11 21 2-3 First edition 1997-03-1 5 Starch and derived products - Heavy metals content - Part 3: Determination of lead content by atomic absorption spectrometry with electrothermal atomization Amidons, fcules et produits driv
2、s - Teneur en mtaux lourds - Partie 3: Determination de la teneur en plomb par spectromtrie dabsorption atomique avec atomisation lectrothermique This material is reproduced from IS0 documents under International Organization for Standardization (60) Copyright License number IHCllCCll996. Not for re
3、sale. No part of these IS0 documents may be reproduced in any form, electronic retrieval system or otherwise, except as allowed in the copyright law of the country of use, or with the prior written consent of IS0 (Case postale 56,1211 Geneva 20, Switzerland, Fax +41 22 734 10 79), IHS or the IS0 Lic
4、ensors members. Reference number IS0 11212-3:1997(E) Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/25/2007 01:09:37 MDTNo reproduction or networking permitted without license from IHS
5、-,-,- STD-IS0 11212-3-ENGL 1997 I Li851903 0703572 1 7 T m IS0 11212-3:1997(E) I 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
6、 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 collaborat
7、es 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 l
8、east 75 % of the member bodies casting a vote. International Standard IS0 1121 2-3 was prepared by Technical Committee ISO/TC 93, Starch (including derivatives and by-products). IS0 11212 consists of the following parts, under the general title Starch and derived products - Heavy metals content - Pa
9、rt I: Determination of arsenic content by atomic absorption spectrometry - Part 2: Determination of mercury content by atomic absorption spectrometry - Part 3: Determination of lead content by atomic absorption spectrometry with electrothermal atomization - Part 4: Determination of cadmium content b
10、y atomic absorption spectrometry with electrothermal atomization Annex A of this part of IS0 11212 is for information only. Q 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, inc
11、luding photocopying and microfilm, without permission in writing from the publisher. International Organization for Standardization Case postale 56 CH-1 21 1 Genve 20 Switzerland Internet central Oiso.ch X.400 c=ch; a400net; p=iso; o=isocs; s=central Printed in Switzerland ii Copyright International
12、 Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/25/2007 01:09:37 MDTNo reproduction or networking permitted without license from IHS -,-,- STDmISO LL232-3-ENGL 1777 4853703 0703573 OOb INTERNATIONAL STANDARD 0
13、 IS0 IS0 11212-3:1997(E) Starch and derived products - Heavy metals content - Part 3: Determination of lead content ,by atomic absorption spectrometry with electrothermal atomization 1 Scope This part of IS0 11212 specifies a method for the determination of the lead content of starch, including deri
14、vatives and by-products, by atomic absorption spectrometry with electrothermal atomization. The number of parameters for the procedure involved in the electrothermal atomization is far larger than in flame atomization; it is thus impossible to propose a comprehensive method likely to ensure the atta
15、inment of satisfactory results on all types of apparatus currently available. Each analyst should therefore optimize the conditions of use of hidher own apparatus on the basis of general or particular instructions. 2 Definition For the purposes of this part of IS0 11212, the following definition app
16、lies. 2.1 lead content: Quantity of lead determined in accordance with the conditions specified in this method and expressed as lead (Pb), in micrograms per kilogram of the product as received. 3 Principle Wet digestion of the organic matrix. Injection of an aliquot portion of digested sample, in th
17、e presence of a matrix modifier, into the furnace of an electrothermal atomization atomic absorption spectrometer. Measurement of the absorbance at a wavelength of 283,3 nm. Determination of the concentration of lead in the sample by means of a calibration curve. 4 Reagents Use only reagents of reco
18、gnized analytical grade and distilled water or water of equivalent purity. 4.1 Nitric acid (pz0 = 1,38 g/ml). 4.2 Hydrogen peroxide, 30 Yo (VW) solution. 1 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 N
19、ot for Resale, 04/25/2007 01:09:37 MDTNo reproduction or networking permitted without license from IHS -,-,- STD-IS0 L12L2-3-ENGL 1777 4851903 0703574 T 4 2 IS0 11212-3:1997(E) I l 4 . 3 Matrix modifier, of the following composition: Ammonium dihydrogen phosphate (NH4)H2P04 Distilled water to make u
20、p to 1 O g 1 O00 ml 4 . 4 Lead standard solution, 1 gA. Standard solutions are commercially available at this concentration. These solutions may be prepared by weighing and dissolving the salt or metal of known purity. 4.5 Calibration solutions Before each series of measurements, prepare from the st
21、andard lead solution (4.4) at least five calibration solutions covering the range of concentrations to be determined. 100 ml of each calibration solution shall contain 7,5 ml of nitric acid (4.1) and 20 ml of the matrix modifier solution (4.3) if the latter is not distributed by the automatic inject
22、ion device. 5 Apparatus All the glassware used shall be previously washed by means of suitable products (such as nitric acid) and rinsed with distilled water to eliminate any trace of lead. Use ordinary laboratory apparatus and, in particular, the following. 5.1 Digestion apparatus (see figure l), m
23、ade of borosilicate glass and consisting of three elements terminating with conical ground joints (5.1.1 to 5.1.3). 5.1.1 Soxhlet extraction tube, of capacity 200 ml, equipped with a stopcock and a lateral tube connected directly to the flask (5.1.3). 5.1.2 Cooling apparatus, 35 cm long, connected t
24、o the top of the Soxhlet extraction tube (5.1.1). 5.1.3 Round-bottom flask, of capacity 250 ml, connected to the lower part of the Soxhlet extraction tube (5.1.1). When the stopcock is open, the device is under reflux; when it is closed, the Soxhlet extraction tube (5.1.1) retains the condensed wate
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