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1、BRITISH STANDARD BS ISO 15517:2003 Tobacco Determination of nitrate content Continuous-flow analysis method ICS 65.160 ? Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 03:29:38 GMT+00:00 2006, Uncontrolled Copy, (c) BSI BS ISO 15517:2003 This British Standard was published under the authorit
2、y of the Standards Policy and Strategy Committee on 11 October 2004 BSI 11 October 2004 ISBN 0 580 44559 3 National foreword This British Standard reproduces verbatim ISO 15517:2003 and implements it as the UK national standard. The UK participation in its preparation was entrusted to Technical Comm
3、ittee AW/40, Tobacco and tobacco products, which has the responsibility to: A list of organizations represented on this committee can be obtained on request to its secretary. Cross-references The British Standards which implement international publications referred to in this document may be found i
4、n the BSI Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of British Standards Online. This publication does not purport to include all the necessary provisions of a contract. Users are responsi
5、ble for its correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the
6、UK interests informed; monitor related international and European developments and promulgate them in the UK. Summary of pages This document comprises a front cover, an inside front cover, the ISO title page, pages ii and iii, a blank page, pages 1 to 7 and a back cover. The BSI copyright notice dis
7、played in this document indicates when the document was last issued. Amendments issued since publication Amd. No. DateComments Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 03:29:38 GMT+00:00 2006, Uncontrolled Copy, (c) BSI INTERNATIONAL STANDARD ISO 15517 First edition 2003-04-15 Referenc
8、e number ISO 15517:2003(E) OSI 2003 Tobacco Determination of nitrate content Continuous-flow analysis method Tabac Dtermination de la teneur en nitrates Mthode par analyse en flux continu BS ISO 15517:2003 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 03:29:38 GMT+00:00 2006, Uncontrolled C
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14、fieldun, na, Mon Nov 27 03:29:38 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ISO 15513002:7)E( ISO 3002 r llAithgs reservde iii Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing Internati
15、onal Standards 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 IS
16、O, also take 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 co
17、mmittees is 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
18、 possibility 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. BS IS
19、O 15517:2003BS ISO 15517:2003 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 03:29:38 GMT+00:00 2006, Uncontrolled Copy, (c) BSI blank BS ISO 15517:2003 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 03:29:38 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ANRETNIITOTS LANDNADRAISO 155130
20、02:7)E( ISO 3002 r llAithgs reservde 1 Tobacco Determination of nitrate content Continuous-flow analysis method 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 unm
21、anufactured tobacco. 2Principle An aqueous extract (see below) of the tobacco is prepared and the nitrate content 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 fo
22、rm the diazo compound. This is coupled with N-1-naphthyl- ethylenediamine dihydrochloride to form a coloured 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 equiva
23、lent results for water and acetic acid extracts. It is recommended that acetic acid extracts should be used 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 goo
24、d laboratory practice and existing national regulations. Use distilled water or water of at least equivalent 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 hydr
25、oxide in distilled water. Add of Brij 35 solution (3.1) and dilute to 1 litre. 3.3Copper sulfate stock solution (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 sulfat
26、e (N2H6SO4, p.a.) in water. Add of copper sulfate stock solution (3.3) and dilute to 1 litre with water. Store 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 n
27、itrate) to approximately of water. Dissolve of sulfanilamide in the solution followed by of N-1-naphthylethylenediamine 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 BS ISO 15517:2003 Licensed Copy: sheffieldun sheffieldun, na
28、, Mon Nov 27 03:29:38 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ISO :71551(3002)E 2 ISO 3002 All rithgs reresvde 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 (KNO3
29、), 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. 3
30、.7.2Working standards From the stock solution (3.7.1), produce a series of at least five calibration solutions whose concentrations cover the range expected to be found in the samples (e.g. to of nitrate). Calculate the exact concentration for each standard. Store in a refrigerator. Prepare fresh so
31、lutions every 2 weeks. If acetic acid (five times) is to be used to extract the nicotine from the test sample in 5.2, the working standards (3.7.2) shall be made from the stock solution every 2 weeks using acetic acid instead of water. 4Apparatus Usual laboratory apparatus and, in particular, the fo
32、llowing items. 4.1Continuous flow analyser consisting of sampler, dialyser, heating bath, delay coils, colorimeter (or equivalent) with filter(s), and recorder. See Annex B for an example of a suitable layout. 5Procedure 5.1Preparation of samples for analysis Prepare the tobacco samples for analysis
33、 by grinding (the sample should totally pass through a sieve) and determine the moisture content. If the tobacco is too wet for grinding, it may be dried at a temperature not exceeding . Any contamination from nitrate and nitrite ions shall be minimized. 5.2Test portion Weigh, to the nearest , appro
34、ximately of the tobacco in a dry conical flask. Add of distilled water from a dispenser. Stopper the flask and shake for . 1)Whatman No. 40 is an example of a suitable product available commercially. This information is given for the convenience of the users of this International Standard and does n
35、ot constitute an endorsement by ISO of this product. 250 ml 0,000 1 g3,3 g 2 mg/ml 10g/ml200g/ml 5 % 5 % 520 nm 1 mm 40 C 0,1 mg250 mg50 ml25 ml 30 min BS ISO 15517:2003 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 03:29:38 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ISO 15513002:7)E( ISO 3
36、002 r llAithgs reservde 3 5.3Preparation of test extract Filter the extract through a Whatman No. 40 (or equivalent) filter paper. Reject the first few millilitres of the filtrate, then collect the filtrate in an analyser cup. Run the samples and standards through the system in the normal manner (e.
37、g. priming with six tobacco extracts, calibration standards and samples with one intermediate calibration solution after every six samples). If sample concentrations lie outside the range of the standards, the samples shall be diluted and run again. 6Calculation 6.1Plot a graph of peak height agains
38、t equivalent nitrate concentrations for all the standard solutions. 6.2Calculate the percentage of nitrate, , on a dry weight basis, in the tobacco using the formula: where is the nitrate concentration, expressed in micrograms per millilitre, obtained from the calibration curve (see 6.1); is the vol
39、ume, in millilitres, of extract prepared (see 5.2) (normally ); is the mass, in milligrams, of the sample (see 5.2); is the moisture content, expressed as percentage by mass, of the tobacco (see 5.1). The test result shall be expressed to two decimal places. When using acetic acid extracts, the stan
40、dard nitrate solutions (3.7) shall be made up with acetic acid and the wash cycle shall be with acetic acid. 7Repeatability and reproducibility An international collaborative study involving 12 laboratories and 3 samples conducted in 1993 showed that when single grades of tobacco were analysed by th
41、is method, the following values for repeatability limit ( ) and reproducibility limit () were obtained. The difference between two single results, found on different extractions by one operator using the same apparatus within a short time interval (the time it takes to analyse 40 sample cups) and wi
42、thout recalibration of the equipment during the time of analysis, will exceed the repeatability limit ( ) on average not more than once in 20 cases in the normal and correct operation of the method. Single results reported by two laboratories will differ by more than the reproducibility limit () on
43、average not more than once in 20 cases in the normal and correct operation of the method. Data analysis gave the estimates as summarized in Tables 1 and 2. For the purposes of calculating and , one test result was defined as the yield obtained from analysing a single extract once. w w = C V 100 m 10
44、00 100 100 M C V25 ml m M 5 %5 % 5 % r R r R rR BS ISO 15517:2003 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 03:29:38 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ISO :71551(3002)E 4 ISO 3002 All rithgs reresvde Table 1 Extraction with water Tobacco typeMean content of nitrateRepeatability
45、 limitReproducibility limit (dry weight) Flue cured 0,110,030,12 Oriental0,160,040,11 Burley2,430,120,41 Table 2 Extraction with acetic acid Tobacco typeMean content of nitrateRepeatability limitReproducibility limit (dry weight) Flue cured 0,110,030,20 Oriental0,160,040,21 Burley2,430,050,39 %rR 5
46、% %rR BS ISO 15517:2003 Licensed Copy: sheffieldun sheffieldun, na, Mon Nov 27 03:29:38 GMT+00:00 2006, Uncontrolled Copy, (c) BSI ISO 15513002:7)E( ISO 3002 r llAithgs reservde 5 Annex A (normative) Optimization of hydrazinium sulfate/copper sulfate A.1General The optimization of the hydrazinium su
47、lfate-copper sulfate reagent (see 3.4) shall be carried out when initially setting up the instrument. It should also be carried out when fresh batches of hydrazinium sulfate are purchased. A.2Reagents A.2.1Standard nitrite stock solution Dissolve of sodium nitrite (NaNO2, p.a.) in distilled water an
48、d dilute to volume in a 1 litre volumetric flask. This solution contains of nitrite. A.2.2Standard nitrite working solution Pipette a aliquot of the stock solution (A.2.1) into a volumetric flask and dilute to volume with distilled water. This solution contains of nitrite. A.3Optimization of the hyd
49、razinium sulfate reagent A.3.1Dilute of the copper sulfate stock solution (3.3) to 1 litre with distilled water. A.3.2Dissolve of hydrazinium sulfate in distilled water and dilute to in a volumetric flask. A.3.3From a burette, dispense , , , ., aliquots of the hydrazinium sulfate solution (refer to A.3.2) into volumetric flasks and dilute to volume with distilled water. These solutions contain , , , ., hydrazinium sulfate per litre. A.3.4Conn