1、DEUTSCHE NORM51422-2Translation 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 the prior permission ofDIN Deutsches Institut fr Normung e. V., Berlin. Beuth Verlag GmbH, 10772 B
2、erlin, Germany,has the exclusive right of sale for German Standards (DIN-Normen).September 2004Testing of petroleum productsGas chromatographic determination of thepurity of cetane and 1-methylnaphthaleneDocument comprises 4 pages.ICS 75.080Prfung von Minerallerzeugnissen Gaschromatographische Besti
3、mmung des Reinheitsgrades Teil 2: Cetan und 1-MethylnaphthalinEnglish price group 6www.din.dewww.beuth.de03.06 9672914In this standard, % (m/m) is used to mean percentage by mass.ForewordThis standard has been prepared by Technical Committee Chromatographische Analyse of the Fachaus-schuss Minerall-
4、 und Brennstoffnormung of the Normenausschuss Materialprfung (Materials Testing Standards Committee).DIN 51422 Testing of petroleum products Gas chromatographic determination of the purity consists of the following Parts:Part 1: n-heptane, isooctane and toluenePart 2: Cetane and 1-methylnaphthaleneA
5、mendmentsThis standard differs from the January 1975 edition as follows:a) The standard has been editorially revised.b) The normative references have been updated.c) The reagents have been more precisely specifi ed.Previous editionDIN 51422-2: 1975-011 ScopeThis standard specifi es a method of deter
6、mining the purity of more than 95 % (m/m) pure cetane (n-hexade-cane) and 1-methylnaphthalene used as reference fuels for determining the ignition quality (cetane number) of diesel fuels (e.g. as specifi ed in DIN 51773). The purity of these reference fuels affects the accuracy of the determination
7、of the cetane number.2 Normative referencesThis standard incorporates, by dated or undated reference, provisions from other publications. These nor-mative references are cited at the appropriate places in the text, and the titles of the publications are listed below. For dated references, subsequent
8、 amendments to or revisions of any of these publications apply to this standard only when incorporated in it by amendment or revision. For undated references, the latest edition of the publication referred to applies (including amendments).DIN 51405 Testing of liquid petroleum products, related liqu
9、ids and solvents for paints and varnishes by gas chromatography GeneralDIN 51750-1 Sampling of petroleum products GeneralSupersedesJanuary 1975 edition.Page 2DIN 51422-2:2004-09DIN 51750-2 Sampling of liquid petroleum productsDIN 51773 Determination of ignition quality (cetane number) of diesel fuel
10、s using the BASF engineDIN EN ISO 4259 Petroleum products Determination and application of precision data in relation to methods of test (ISO 4259:1992 + Corr 1:1993)3 PrincipleA sample is analysed by injecting it in liquid form into a gas chromatographic column containing a suitable liquid as stati
11、onary phase. It is conveyed through the column by an inert gas and separated into its individual components. The signals due to the latter are recorded by a detector as they emerge from the column. The content of the main component is reported as a percentage by mass.4 Apparatus and reagentsThe foll
12、owing equipment and reagents shall be used.4.1 Gas chromatograph, having a liquid sample inlet, a suitable detector (e.g. a fl ame ionisation detector as in DIN 51405) and a suitable recording and evaluation unit.4.2 Separating columns, having a recommended column length of 50 m and an internal diam
13、eter of about 0,25 mm. Any capillary column that meets the requirements specifi ed in subclause 5.2 may be used as sepa-rating column.Apiezon L and polyphenyl ether OS 138 have in practice been found to be satisfactory stationary phases for cetane and 1-methylnaphthalene, respectively. Equally suita
14、ble are other impregnated stationary phases, such as silicone oil DC 200, phenyl silicone oil DC 550, polyphenyl ether OS 124, silicone rubber SE 30 and silicon rubber OV 1.1)4.3 Microinjection syringe, having a capacity not exceeding 10 l.4.4 Operating gases4.4.1 Carrier gasesThe following carrier
15、gases may be used: high-purity nitrogen; high-purity helium; high-purity argon.4.4.2 Detector gasesIf a fl ame ionization detector is used, the following detector gases are suitable: high-purity hydrogen; high-purity air.4.3 ReagentsAll the reagents used shall have a purity of not less than 98 % (m/
16、m): n-dodecane; n-tetradecane; n-pentadecane; n-hexadecane; naphthalene; 1-methylnaphthalene.5 Gas chromatograph operating conditions5.1 Gas chromatograph settingsThe settings will depend on the type of equipment used. The values given below have proved satisfactory in analytical practice and may be
17、 used as a guideline.1) Information on sources of supply is obtainable from Fachausschuss Minerall- und Brennstoffnormung, Kapstadtring 2, 20297 Hamburg, Germany.Page 3DIN 51422-2:2004-095.1.1 Examples of temperature settingsSample inlet: 300 C;Separating column: 170 C;Detector: 250 C.5.1.2 Carrier
18、gas division ratioA ratio of about 1:100 is recommended.5.1.3 Detection sensitivityTo determine impurities in cetane and 1-methylnaphthalene, the equipment shall be set so that 0,02 % (m/m) tridecane or tetradecane can be determined to an accuracy of 0,002 % (m/m) under the specifi ed analytical con
19、ditions.5.2 Resolution of columnIn order to separate paraffi ns satisfactorily from aromatics and also to separate members of these groups from one another, the column shall meet the following conditions.5.2.1 To determine the purity of cetane, the resolution, RB, of the column determined by the ful
20、l width at half height method (see DIN 51405) shall be at least 10 for n-hexadecane and n-pentadecane under the analytical conditions.5.2.2 To determine the purity of 1-methylnaphthalene, the resolution, RB, of the column determined by the full width at half height method (see DIN 51405) shall in al
21、l cases be at least 10 for naphthalene and methylnaphtha-lene and for 1-methylnaphthalene and n-tetradecane under the analytical conditions. The n-tetradecane peak shall appear before that of 1-methylnaphthalene.6 SamplingAs specifi ed in DIN 51750-1 and DIN 51750-2.7 ProcedureWeigh out 100 ml of sa
22、mple to an accuracy of t 0,1 g, add about 0,2 ml of n-dodecane weighed to an accuracy of t 0,2 mg and mix thoroughly. Inject 1,5 l of this mixture into the sample inlet of the gas chromatograph using the injection syringe. Measure the peak areas of the internal standard and all the impurities whose
23、retention time does not exceed twice the retention time of the main component.If n-dodecane is one of the impurities, use another internal standard.8 EvaluationCalculate the purities of cetane and 1-methylnaphthalene, in % (m/m), using the following equation:Purity =100 100AmAmVsBpwhereAVis the sum
24、of the peak areas of all the impurities;ABis the peak area of the internal standard;msis the initial mass of the internal standard, in g;mpis the initial mass of the sample, in g.When evaluating the peak area, bear in mind that impurities appearing as superimposed on the peak of the main component m
25、ay give rise to errors.NOTE: It was decided not to specify conversion factors for the impurities.9 Expression of resultRefer to this standard and report the purity in % (m/m), rounding to the nearest 0,1 % (m/m).Page 4DIN 51422-2:2004-0910 PrecisionCf. DIN EN ISO 425910.1 Repeatability(same operator
26、, same equipment)If two results are obtained under repeatability conditions, both results shall be considered acceptable and in conformity with this standard if they differ by no more than 0,2 % (m/m).10.2 Reproducibility(different operators, different equipment)If two laboratories each obtain a result under reproducibility conditions, both results shall be considered acceptable and in conformity with this standard if they differ by no more than 0,7 % (m/m).
