ISO-15517-2003.pdf
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1、INTERNATIONAL STANDARD ISO 15517 First edition 2003-04-15 Reference number ISO 15517:2003(E) ISO 2003 Tobacco Determination of nitrate content Continuous-flow analysis method Tabac Dtermination de la teneur en nitrates Mthode par analyse en flux continu Copyright International Organization for Stand
2、ardization Provided by IHS under license with ISO Licensee=Aramco HQ/9980755100 Not for Resale, 04/23/2007 03:35:51 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 15517:2003(E) ii ISO 2003 All rights reserved PDF disclaimer This PDF file may contain embedded typefaces.
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5、for printing. Every care has been taken to ensure that the file is suitable for use by ISO member bodies. In the unlikely event that a problem relating to it is found, please inform the Central Secretariat at the address given below. ISO 2003 All rights reserved. Unless otherwise specified, no part
6、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 either ISO at the address below or ISOs member body in the country of the requester. ISO copyright office Case postale 56
7、CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Aramco HQ/9980755100 Not for Resale, 04/23/2007 03:35:51 MDTNo repr
8、oduction or networking permitted without license from IHS -,-,- ISO 15517:2003(E) ISO 2003 All rights reserved iii Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standar
9、ds 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 liaison with ISO, also take
10、 part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is
11、to prepare International Standards. 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. Attention is drawn to the possibility
12、 that some 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. ISO 15517 was prepared by Technical Committee ISO/TC 126, Tobacco and tobacco products, Subcommittee SC 2, Leaf tobacco. Copyright Interna
13、tional Organization for Standardization Provided by IHS under license with ISO Licensee=Aramco HQ/9980755100 Not for Resale, 04/23/2007 03:35:51 MDTNo reproduction or networking permitted without license from IHS -,-,- . iv Copyright International Organization for Standardization Provided by IHS und
14、er license with ISO Licensee=Aramco HQ/9980755100 Not for Resale, 04/23/2007 03:35:51 MDTNo reproduction or networking permitted without license from IHS -,-,- INTERNATIONAL STANDARDISO 15517:2003(E) ISO 2003 All rights reserved 1 Tobacco Determination of nitrate content Continuous-flow analysis met
15、hod 1Scope This International Standard specifies a method for the determination of the nitrate content in tobacco by continuous-flow analysis. This method is applicable to manufactured and unmanufactured tobacco. 2Principle An aqueous extract (see below) of the tobacco is prepared and the nitrate co
16、ntent of the extract is determined by reduction of the nitrate ions to nitrite ions with hydrazinium sulfate in the presence of a copper catalyst, followed by reaction with sulfanilamide to form the diazo compound. This is coupled with N-1-naphthyl- ethylenediamine dihydrochloride to form a coloured
17、 complex, which is measured at . If there is any nitrite content, it will be detected and included in the nitrate content result. Collaborative studies have shown that this method gives equivalent results for water and acetic acid extracts. It is recommended that acetic acid extracts should be used
18、if nitrate and reducing substances (see ISO 15153) or reducing carbohydrate analyses (see ISO 15154) are to be carried out simultaneously. 3Reagents All reagents shall be used according to good laboratory practice and existing national regulations. Use distilled water or water of at least equivalent
19、 purity. 3.1Polyoxyethylene lauryl ether (Brij 35 solution) Add 1 litre of water to of Brij 35. Warm and stir until dissolved. 3.2Sodium hydroxide solution (NaOH), p.a. Dissolve of sodium hydroxide in distilled water. Add of Brij 35 solution (3.1) and dilute to 1 litre. 3.3Copper sulfate stock solut
20、ion (CuSO4), p.a. Dissolve of copper(II) sulfate pentahydrate in distilled water and dilute to . 3.4Hydrazinium sulfate/copper sulfate reagent Dissolve the optimum amount of hydrazinium sulfate (N2H6SO4, p.a.) in water. Add of copper sulfate stock solution (3.3) and dilute to 1 litre with water. Sto
21、re in an amber glass bottle. Prepare a fresh solution every month. 3.5Sulfanilamide reagent (NH2C6H4SO2NH2) Add of concentrated orthophosphoric acid (H3PO4, volume fraction , of grade low in nitrate) to approximately of water. Dissolve of sulfanilamide in the solution followed by of N-1-naphthylethy
22、lenediamine dihydrochloride (C10H7NHCH2CH2NH22HCI). 520 nm 5 % 5 % 250 g 8,0 g1 ml 1,20 g100 ml 1,5 ml 25 ml85 % 175 ml2,5 g0,125 g Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=Aramco HQ/9980755100 Not for Resale, 04/23/2007 03:35:51 MDTNo
23、reproduction or networking permitted without license from IHS -,-,- ISO 15517:2003(E) 2 ISO 2003 All rights reserved Dilute to with water and filter through a Whatman No. 401) (or equivalent) filter paper. Store in an amber glass bottle. Prepare a fresh solution every 2 days. 3.6Potassium nitrate (K
24、NO3), p.a. 3.7Standard nitrate solutions 3.7.1Stock solution Weigh, to the nearest , approximately of potassium nitrate (3.6). Dissolve in water and dilute to 1 litre in a volumetric flask. This solution contains approximately of nitrate. Store in a refrigerator. Prepare a fresh solution every month
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