1、DEUTSCHE NORM Auaust 199% Liquid petroleum products Determination of benzene content by gas chromatography English version of DIN EN 12177 Unleaded petrol DIN EN 12177 - ICs 75.160.20 Descriptors: Petrol, unleaded, benzene content, testing. Flssige Minerallerzeugnisse - Unverbleiter Ottokraftstoff -
2、 Bestimmung des Benzolgehaltes mittels Gasch romatog raph ie European Standard EN 121 77 : 1998 has the status of a DIN Standard. A comma is used as the decimal marker. National foreword This standard has been prepared by CEN/TC 19. The responsible German body involved in its preparation was the Nor
3、menausschu Materialprfung (Mate- rials Testing Standards Committee). The DIN Standards corresponding to the EuropeanAnternational Standards referred to in clause 2 of the EN are as follows: EuropeanAnternational Standard DIN Standards EN IS0 3675 EN IS0 3838 EN IS0 121 85 IS0 31 70 DIN 51 750-1 and
4、DIN 51 750-2 DIN 51757 and DIN EN IS0 3675 DIN 51 757 and DIN EN IS0 3838 DIN EN IS0 12185 National Annex NA Standards referred to (and not included in Normative references) DIN 51 750-1 DIN 51 750-2 DIN 51 757 DIN EN IS0 3675 DIN EN IS0 3838 DIN EN IS0 12185 Sampling of petroleum products - General
5、 Sampling of liquid petroleum products Determination of density of petroleum products Crude petroleum and liquid petroleum products - Laboratory determination of density or relative density by the hydrometer method (IS0 3675 : 1993) Determination of density or relative density of crude petroleum and
6、 liquid or solid petroleum products by the capillary-stoppered pycnometer and graduated bicapillary pycnometer methods (IS0 3838 : 1983) Determination of density of crude petroleum and petroleum products by the oscillating U-tube method (IS0 12185 : 1996) EN comprises 13 pages. No pari of this stand
7、ard may be reproduced without the prior permission of Ref. No. DIN EN 12177: 1998-0 Y Deutsches Institut fr Normung e. V., Berlin. wth Verlag GmbH, D-10772 Berlin, has the exclusive right of sale for German Standards (DIN-Normen). English price group O9 Sales No. 1109 12.98 EUROPEAN STANDARD NORME E
8、UROPENNE EUROPISCHE NORM EN 12177 April 1998 ICs 75.160.20 Descriptors: Petrol, unleaded, benzene content, testing English version Liquid petroleum products Determination of benzene content by gas chromatography Unleaded petrol Produits ptroliers liquides - Essence sans plomb - Dtermination de la te
9、neur en benzne par chromatogra- phie en phase gazeuse Flssige Minerallerzeugnisse - Unverbleite Ottokraftstoffe - Bestim- mung des Benzolgehaltes mittels Gasch romatog raph ie This European Standard was approved by CEN on 1998-03-23. CEN members are bound to comply with the CENKENELEC Internal Regul
10、ations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national stand- ards may be obtained on application to the Central Secretariat or to any CEN member. The E
11、uropean Standards exist in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official versions. CEN members are the n
12、ational standards bodies of Austria, Belgium, the Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, the Netherlands, Norway, Portugal, Spain, Sweden, Switzerland, and the United Kingdom. CEN European Committee for Standardization Comit Europen de Normali
13、sation Europisches Komitee fr Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels O 1998. CEN - All rights of exploitation in any form and by any means reserved worldwide for CEN national members. Ref. No. EN 12177 : 1998 E Page 2 EN 121 77 : 1998 Foreword This European Standard has bee
14、n prepared by Technical Committee CEN/TC 19 “Petroleum products, lubricants and related products”, the secretariat of which is held by NNI. This European Standard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by October
15、1998, and conflicting national standards shall be withdrawn at the latest by October 1998. According to the CENKENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finla
16、nd, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom. In this standard annex A is informative. Page 3 EN 121 77 : 1998 1 Scope This European standard specifies a column switching gas chromatographic method
17、for the quantitative determination of benzene content in the range 0,05 % (V/W to 6 % (V/M in unleaded petrol having a final boiling point not greater than 220 “C. The method described in this standard is suitable for determining benzene in petrol, including petrol containing oxygenates, in line wit
18、h the relevant EC Directives“. NOTE : For the purposes of this European Standard, the terms “% (V/W“ and “% (mh)“ are used to represent respectively the volume fraction and the mass fraction. WARNING : The use of this standard may involve hazardous materials, operations and equipment. This standard
19、does not purport to address all of the safety problems associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. 2 Normative references This European Stan
20、dard incorporates by dated or undated reference, provisions from other publications. These normative references are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to
21、 this standard only when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies. EN IS0 3675 Crude petroleum and liquid petroleum products - Laboratory determination of density or relative density - Hydrometer method (IS0 3675: 1
22、993) EN IS0 3838 Crude petroleum and liquid or solid petroleum products - Determination of density or relative density - Capillary-stoppered pyknometer and graduated bicapillary pyknometer methods (IS0 3838: 1 983) EN IC0 12185 Crude petroleum and petroleum products - Determination of density - Osci
23、llating U-tube method (IS0 121 85:1996) IS0 3170 Petroleum liquids - Manual sampling IC0 3171 Petroleum liquids - Automatic pipeline sampling 3 Principle The benzene-containing fraction is isolated from the sample using a capillary column and, in a second capillary column, the benzene is separated a
24、nd detected using a flame ionization detector. ) EC Directive 85/210/EEC, Council Directive on the approximation of the laws of the Member States concerning the lead content of petrol. EC Directive 85/536/EEC, Council Directive on crude-oil savings through the use of substitute fuel components in pe
25、trol. Page 4 EN 121 77 : 1998 NOTE 1 : Some oxygenates are known to interfere with the determination of benzene using a single column gas chromatographic method. NOTE 2 : Guidance on the column switching technique is given in annex A. 4 Reagents and materials Use only reagents of recognized analytic
26、al grade. 4.1 Carrier gas Hydrogen, helium, or nitrogen, free of hydrocarbons. WARNING : Hydrogen is explosive in mixtures with air at concentrations of hydrogen ranging approximately from 4 % (V/W to 75 % WW. All joints and lines carrying hydrogen shall be made gas tight to prevent leakage of hydro
27、gen into a confined space. 4.2 Reagents for the preparation of calibration samples NOTE: Calibration samples will normally be combinations of benzene, solvent and an internal standard. 4.2.1 Benzene Not less than 99,0 % (m/m) pure. WARNING : Benzene is toxic and carcinogenic. 4.2.2 Solvent Not conta
28、ining benzene or internal standard, e.g. heptane. 4.3 Internal standard Reagent for which it has been established that it is not present in the sample. NOTE : Isobutyl methyl ketone is preferred as the internal standard. 5 Apparatus Usual laboratory apparatus and glassware, together with the followi
29、ng: 5.1 Gas chromatographic assembly 5.1.1 Gas chromatograph, provided with a means for column switching, equipped with a programmable oven temperature controller, or controllers in the case of dual oven gas chromatographs, and two flame ionization detectors (FID). NOTE : It is recommended that a sy
30、stem constructed entirely of glass from the sample injection port up to the detector system is used since petrol may contain oxygenates which can give rise to corrosion and changes of retention times in systems constructed partly using metals. Page 5 EN 12177: 1998 5.1.2 Two capillary columns, of ap
31、propriate dimensions, each internally coated with a substance of different polarity, such that the resolution between the benzene peak and the matrix is at least 1 after elution from the second column. The resolution, R, between peaks A and B (see figure 1) is calculated using the equation: where tA
32、 is the reduced retention time of component A; fB is the reduced retention time of component B; wA is the peak width at half-height of component A; wB is the peak width at half-height of component B. A Start I l - Time axis a N tA 8 a ti i3 Time axis NOTE : tN is the hold-up time zero of the column,
33、 .e. the time taken for an inert component, such as methane, to travel through the column without chromatography taking place. Figure 1 - Calculation of the resolution between peaks A and B 5.1.3 Device for the control of the flow of carrier gas. 5.1.4 Recorder and/or integrator An amplifier and pot
34、entiometric recording device, or an integrator or data processor system, giving area values corresponding to the peak area in square millimetres. 5.2 Injection device Page 6 EN 121 77 : 1998 5.3 fitted with a self-sealing rubber septum coated with polytetrafluoroethylene (PTFE). Test sample containe
35、r, normally with a capacity of between 1 O ml and 1 O0 ml, 6 Sampling Unless otherwise specified in the commodity specification, samples shall be taken as described in IS0 3170 or IS0 3171, and/or in accordance with the requirements of national standards or regulations for the sampling of petrol. 7
36、Procedure 7.1 Setting up the apparatus 7.1.1 General Prepare the equipment and set the test conditions in accordance with the manufacturers instructions. 7.1.2 Carrier gas Adjust the pressure and flow rate of the carrier gas to levels such that the resolution is in accordance with 5.1.2. 7.2 Calibra
37、tion Prepare the calibration sample by combining known masses of benzene (4.2.1) and internal standard (4.3) in a suitable solvent (4.2.2). Inject a suitable quantity of the prepared calibration sample into the gas chromatograph such that the capacity of the columns and other components is not excee
38、ded and the linearity of the detector is not impaired. Determine and record the retention times for benzene and for the internal standard. Calculate the calibration factor, f, for benzene using the following equation: where rn, is the mass of benzene in the calibration sample, in grams; A, is the pe
39、ak area of the internal standard, in square millimetres; A, is the peak area of benzene, in square millimetres; m2 is the mass of the internal standard in the calibration sample, in grams. Page 7 EN 12177: 1998 7.3 Determination of density Determine the density at 15 OC, ps , of the sample in accord
40、ance with either EN IS0 3675, EN IS0 3838 or EN IS0 12185 and record the result to the nearest 0,l kg/m3. 7.4 Preparation of test sample Cool the sample to between 5 OC and 10 “C. Weigh, to the nearest 0,l mg, the test sample container (5.3) and its rubber septum without sealing it. Transfer a quant
41、ity of the internal standard (4.3) to the test sample container and weigh, to the nearest 0,l mg, the test sample container with contents and septum, without sealing the sample container. The mass, m, in grams, of the internal standard shall amount to between 2 % (m/m) and 5 % (m/m) of the sample, m
42、, but shall not be less than 0,050 g. Transfer a quantity, normally between 5 ml and 100 ml, of the cooled sample to the test sample container and seal immediately with the septum. Weigh, to the nearest 0,l mg, the test sample container and contents. Record the mass, ms, in grams, of the test sample
43、 taken, to the nearest 0,l mg. Record the amount of internal standard in the prepared test sample as a percentage by mass. Mix the contents of the test sample container by shaking until homogeneous. 7.5 Introduction of test portion Inject a suitable quantity of the prepared test sample (7.4) into th
44、e gas chromatograph. Ensure that the test portion size is such that the capacity of the columns and other components of the gas chromatograph is not exceeded and that the linearity of the detector is not impaired. 7.6 Examination of the gas chromatogram Examine the gas chromatogram and identify the
45、benzene and the internal standard by means of their retention times (see 7.2). 8 Calculation 8.1 Calculation of mass of benzene in the test sample Calculate the mass, m, in grams, of benzene in the test sample using the following equation: where f is the calibration factor for benzene; A, is the pea
46、k area of benzene, in square millimetres; Page 8 EN 121 77 : 1998 m, is the mass of the internal standard in the test sample (see 7.41, in grams; A, is the peak area of the internal standard, in square millimetres. 8.2 Calculation of volume of benzene in the test sample Calculate the volume, V, in m
47、illilitres, of benzene in the test sample using the following equation: where : m3 pb is the mass of benzene in the test sample (see 8.1 1, in grams; is the density of benzene at 15 OC, .e. 884,3 kg/m3. 8.3 Calculation of volume of test sample Calculate the volume, V, in millilitres, of the test sam
48、ple using the following equation: ms x 1000 Ps VZ = where : m5 ps is the mass of the test sample (see 7.41, in grams; is the density at 15 “C of the sample, in kilograms per cubic metre. 8.4 Calculation of benzene content as % (VN) Calculate the benzene content, 4, of the sample as a percentage by v
49、olume using the following equation: vi x 100 v2 9= where : V, V, is the volume of benzene in the test sample (see 8.21, in millilitres; is the volume of the test sample (see 8.31, in millilitres. Page 9 EN 12177: 1998 Benzene content % (VIV) 9 Expression of results Repeatability, r Reproducibility, R % (VIV) % (VIV) Report the benzene content to the nearest 0,l % (WW. 0,15 to 1,50 1,50 to 6,OO IO Precision 0,03 0,lO 0,05 0,25 1 O. 1 Repeatability, r The difference between two test results, obtained by the same operator with the same apparatus under constant operati
