1、 DEUTSCHE NORMJuly 2004DIN 51437 ICS 71.080.15 Supersedes DIN 51437:1989-04 Testing of benzene and benzene homologues Determination of the non-aromatics, toluene and C8-aromatics content of benzene Gas chromatography Prfung von Benzol und Benzolhomologen Bestimmung des Gehaltes an Nichtaromaten, Tol
2、uol und C8-Aromaten in Benzol Gaschromatographie Document comprises 5 pagesTranslation by DIN-Sprachendienst. In case of doubt, the German-language original should be consulted as the authoritative text. No part of this translation may be reproduced without prior permission of DIN Deutsches Institut
3、 fr Normung e. V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany, has the exclusive right of sale for German Standards (DIN-Normen). English price group 6 www.din.de www.beuth.de !,o-F“11.06 9761035DIN 51437:2004-07 2 Foreword The present standard has been prepared by Technical Committee 614 Gasc
4、hromatographische Analyse in collaboration with Technical Committee 644 Prfung von Spezialbenzinen, Testbenzinen, Lsemittel of Fach-ausschuss Minerall- und Brennstoffnormung of the Normenausschuss Materialprfung (Materials Testing Standards Committee). Amendments This standard differs from DIN 51437
5、:1989-04 as follows: a) The references have been updated. b) The precision data have been updated. c) The standard has been editorially revised. Previous edition DIN 51437: 1989-04 1 Scope This standard specifies a method of determining contents of up to 1 500 mg/kg of non-aromatics, of up to 300 mg
6、/kg of toluene and of up to 300 mg/kg of C8-aromatics in benzene that meets the requirements of DIN 51633. The test will provide either information about the purity of the benzene or an indication of its composition. When handling benzene, the relevant safety instructions and national regulations ar
7、e to be observed (e.g. Verordnung ber brennbare Flssigkeiten (German Regulation on flammable liquids) or Gefahrstoff-verordnung (German Regulation on dangerous substances and materials). 2 Normative references This standard incorporates, by dated or undated reference, provisions from other publicati
8、ons. These normative references are cited at the appropriate places in the text, and the titles of the publications are listed below. For dated references, subsequent amendments to or revisions of any of these publications apply to this standard only when incorporated in it by amendment or revision.
9、 For undated references, the latest edition of the publication referred to (including amendments) applies. DIN 51405:2004-01, Testing of liquid petroleum products, related liquids and solvents for paints and varnishes by gas chromatography General DIN 51633, Benzene and benzene homologues Requiremen
10、ts DIN 51750-1, Sampling of petroleum products General DIN 51750-2, Sampling of liquid petroleum products DIN EN ISO 4259, Petroleum products Determination and application of precision data in relation to methods of test (ISO 4259:1992 + Cor 1:1993) DIN 51437:2004-07 3 Verordnung ber brennbare Flssi
11、gkeiten (German Regulation on flammable liquids), as of 13 December 1996, BGBl (German Federal Law Gazette) I, 1996, 65, pp. 1937-19521)Gefahrstoffverordnung (German Regulation on dangerous substances and materials), as of 15 November 1999, BGBl (German Federal Law Gazette) I, 1999, No. 52, pp. 2233
12、-22811)3 Principle The sample to be analysed is resolved into non-aromatic and aromatic hydrocarbons by gas chromatography using a polar separating column. The determination requires the use of an internal standard. 4 Designation Designation of the method of determining non-aromatics, toluene and C8
13、-aromatics in benzene by gas chromatography: Test DIN 51437 GC 5 Apparatus and reagents The following equipment and reagents shall be used. 5.1 Gas chromatograph, meeting the general requirements of DIN 51405 and fitted with a flame ionization detector (FID). 5.2 Capillary column, containing a polar
14、 separating phase, providing complete resolution of the components to be determined and having a resolution, R, of the last non-aromatic detected and of the inner standard of at least 1. Before the column is used, its resolution, R, shall be checked as specified in DIN 51405 using a mixture of equal
15、 parts of the substances to be determined in a suitable solvent, for example analytical grade benzene, with a purity of 99,999 % (m/m) achieved by repeated crystallization. NOTE The precision data in clause 10 relate to interlaboratory tests using 50 m polar capillary columns and 4 m to 6 m packed c
16、olumns containing Fraktonitril III2)or Carbowax2). The use of other columns does not automatically ensure that the precision data in this standard will be maintained. 5.3 Injection syringes, of 10 l and 100 l capacity 5.4 Sample vessel, having a self-sealing rubber membrane closure coated with polyt
17、etrafluoroethylene (PTFE). 5.5 Gases, having a purity of not less than 99,5 % (m/m). Cf. subclause 4.3 of DIN 51405:2004-01. Nitrogen, as carrier gas. Hydrogen and air, as detector gases. 1) Registered in the DITR database of DIN Software GmbH, obtainable from Beuth Verlag GmbH, 10772 Berlin, German
18、y. 2)Reference to Fraktonitril IIIand Carbowaxis for the purpose of providing the user with examples of commercially available products and does not imply approval by DIN. DIN 51437:2004-07 4 5.6 Internal standard, e.g. 99,0 % (m/m) n-nonane or n-undecane. 6 Sampling As in DIN 51750-1 and DIN 51750-
19、2. 7 Procedure 7.1 Preparation of analytical sample After weighing the sample vessel with its rubber membrane closure, introduce the appropriate mass of sample into the vessel and seal the latter immediately using the rubber membrane closure. Then weigh the sample vessel with its closure to determin
20、e the mass of the sample, in g. Take an amount of internal standard that will give a peak area in the chromatogram approximately equal to the peak areas of the impurities and inject it through the rubber membrane closure using the 100 l syringe. Weigh the sample vessel with its closure again to dete
21、rmine the mass of the internal standard. 7.2 Preparation of apparatus and test conditions Cf. subclause 5.2 of DIN 51405. Adjust the pressure and flowrate of the carrier gas so that, at a given column temperature, the separation is as in subclause 6.2 of DIN 51405. 7.3 Amount of sample and its appli
22、cation Cf. subclause 5.3 of DIN 51405. Take a mass of sample that will not exceed the capacity of the separating column and will ensure the linearity of the detector. 7.4 Recording Cf. subclause 5.4 of DIN 51405. Analyse the sample under isothermal conditions. 8 Evaluation Cf. subclause 6.2 of DIN 5
23、1405. Calculate the content by mass, w(X), in mg/kg, of non-aromatics, toluene and C8-aromatics using the following equation: ()PStStXmAmAwi= where Aiis the sum of the peak areas of all the non-aromatics or the peak area of toluene or the sum of the peak areas of the C8-aromatics; AStis the peak are
24、a of the internal standard; mStis the initial mass of the internal standard, in mg; DIN 51437:2004-07 5 mPis the initial mass of sample, in g; X stands for the substance being determined by gas chromatography. No conversion factors have been included. 9 Expression of results Refer to this standard a
25、nd report the content by mass, w(X), in mg/kg, of non-aromatics, toluene and C8-aromatics rounded to the nearest 1 mg/kg. 10 Precision See DIN EN ISO 4259. Repeatability limit (Same operator same equipment) The difference between two successive results obtained under repeatability conditions will no
26、t exceed the values specified in the table in more than 5 % of cases. Reproducibility limit (Different operators, different equipment) The difference between two individual results obtained under repeatability conditions will not exceed the values specified in the table in more than 5 % of cases. Table 1 Repeatability and reproducibility limits Range, in mg/kg Repeatability limit, r Reproducibility limit, R Non-aromatics 200 0,10 X 0,15 X 200 0,03 X 0,10 X Toluene 300 0,05 X 0,10 X C8-aromatics 100 0,08 X 0,30 X 100 0,08 X 0,20 X X is the mean of two comparable results
