DIN 51790-7-2002 Testing of liquid fuels - Determination of the vanadium and nickel content - Part 7 Analysis by wavelength dispersive X-ray spectrometry (XRS) and Fundamental-Para.pdf

1、ICS 75.160.20Prfung flssiger Brennstoffe Bestimmung des Vanadium- und Nickelgehaltes Teil 7:Rntgenfluoreszenz-Analyse nach der Fundamental-Parameter-MethodeIn keeping with current practice in standards published by the International Organization for Standardization(ISO), a comma has been used throug

2、hout as the decimal marker.Ref. No. DIN 51790-7 : 2002-01English price group 05 Sales No. 010506.03DEUTSCHE NORM January 200251790-7Continued on pages 2 to 5. No part of this translation may be reproduced without the prior permission ofDIN Deutsches Institut fr Normung e.V., Berlin. Beuth Verlag Gmb

3、H, 10772 Berlin, Germany,has the exclusive right of sale for German Standards (DIN-Normen).Determining the vanadium and nickel content of liquidfuels by wavelength dispersive X-ray spectrometryusing the fundamental parameter methodTranslation by DIN-Sprachendienst.In case of doubt, the German-langua

4、ge original should be consulted as the authoritative text.ForewordThis standard has been prepared by Technical Committee Rntgenfluoreszenz-Analyse nach der Funda-mental-Parameter-Methode of Fachausschuss Minerall- und Brennstoffnormung of the NormenausschussMaterialprfung (Materials Testing Standard

5、s Committee).1 ScopeThe method specified in this standard serves to determine vanadium contents up to 500 mg/kg (m/m) andnickel contents up to 100 mg/kg (m/m) of homogeneous liquid petroleum products and fuels by wavelength-dispersive X-ray spectrometry.The sulfur content of the samples (where it do

6、es not exceed 3 % (m/m) is determined by the method as amatter of course. Although the results can be used in practice, it may be better to use the relevant sulfurdetermination methods if only the sulfur content of a sample is of interest.The method may also be used for analysing solid petroleum pro

7、ducts or additives if they can be homoge-neously dissolved in an organic solvent.2 Normative referencesThis standard incorporates, by dated or undated reference, provisions from other publications. Thesenormative references are cited at the appropriate places in the text, and the titles of the publi

8、cations arelisted below. For dated references, subsequent amendments to or revisions of any of these publicationsapply to this standard only when incorporated in it by amendment or revision. For undated references, thelatest edition of the publication referred to applies.DIN 1333 Presentation of num

9、erical dataDIN 51418-1 X-ray emission and X-ray fluorescence analysis General concepts and basic principlesDIN 51418-2 X-ray emission and X-ray fluorescence analysis Terminology and principles of meas-urement, calibration and evaluationDIN 51750-1 Sampling of petroleum products GeneralDIN 51750-2 Sa

10、mpling of liquid petroleum productsDIN EN ISO 4259 Petroleum products Determination and application of precision data in relation tomethods of test (ISO 4259 : 1992 + Corr 1 : 1993).3 UnitThe unit in which the vanadium and nickel contents are expressed is mg/kg and that in which the sulfurcontent is

11、 expressed is percentage by mass.Page 2DIN 51790-7 : 2002-014 PrincipleThe sample to be analysed is transferred to a sample vessel and exposed to the primary radiation from an X-ray tube. The count rates of the KaX-ray fluorescence radiation thus emitted and those of the backgroundradiation are meas

12、ured.The vanadium, nickel and sulfur contents are determined from calibration graphs prepared on the basis ofreference solutions and software for calculating the correction factors.The method is generally applicable to samples of any composition, irrespective of the type of vanadium, nickelor sulfur

13、 compounds detected and of any other elements they contain.5 ApparatusIn addition to standard laboratory equipment, the following shall be used.5.1 Wavelength dispersive X-ray spectrometer (cf. DIN 51418-1 and DIN 51418-2), capable of measuringthe count rates of the KaX-ray fluorescence radiation an

14、d having the following parameters.a) X-ray tube, meeting the following requirements:Anode: rhodium, chromium or scandium.Voltage: at least 30 kV.Current: at least 40 mA.b) Collimator aperture: narrow.c) Crystal analyser: lithium fluoride, pentaerythritol or germanium.d) X-ray path: helium.e) Measuri

15、ng cell window: polyethylene terephthalate film1) or polyester film, not more than 6 m thick.f) Detector: continuous-flow proportional counter, with pulse height analyser.5.2 Software, for the fundamental parameter method of calculating the appropriate alpha correction factors(this may be part of th

16、e spectrometer software or separate software)1).5.3 Balance, with 0,1 mg scale intervals.5.4 Stirrer, capable of being heated.6 ReagentsThe standards used shall not contain the analytes. Multi-element standards shall not be used. The individualcontents of vanadium, nickel and sulfur in the reagents

17、shall not exceed 1 mg/kg.The following reagents shall be used.6.1 Di-n-butyl sulfide, having a sulfur content of 21,9 %. Or, alternatively:6.2 Vanadium standard (e.g. bis(1-phenyl-1,3-butanedionato)oxovanadium(IV) or any other oil-soluble va-nadium compound, or any commercially available solution of

18、 known vanadium content).6.3 Nickel standard (e.g. nickel cyclohexanebutyrate or any other oil-soluble nickel compound, or anycommercially available solution of known nickel content).6.4 Low-viscosity paraffin.6.5 Acetylacetone.6.6 Pure 2-ethylhexanoic acid.6.7 Vanadium stock solution, prepared by d

19、issolving the required amount of vanadium standard (e.g.bis(1-phenyl-1,3-butanedionato)oxovanadium(IV) in low-viscosity paraffin and adding 1,5 % acetylacetone.The solution is stable only for a limited time; as soon as cloudiness appears, stop using the solution.6.8 Nickel stock solution, prepared b

20、y dissolving the required amount of nickel standard (e.g. nickelcyclohexanebutyrate) in low-viscosity paraffin and adding 5 % 2-ethylhexanoic acid.7 SamplingAs in DIN 51750-1 and DIN 51750-2.1) Information on sources of supply is obtainable from Fachausschuss Minerall- und Brennstoffnormung(FAM), Ka

21、pstadtring 2, 22297 Hamburg, Germany.Page 3DIN 51790-7 : 2002-018 Plotting the calibration graphsPrepare reference solutions having the concentrations shown in table 1, by diluting the individual stock solu-tions with low-viscosity paraffin or by diluting commercial solutions.Table 1: Reference solu

22、tions9 Measurement of reference solutionsWeigh the reference solutions to an accuracy of 0,1 mg into the sample vessel and expose them consecutivelyto X-ray radiation. Measure the count rates, I, for the X-ray fluorescence radiation and background radiationas specified in table 2, adapting the wavel

23、ength of each background radiation to be measured to the specificrequirements.Standards containing sulfur may be used, if their sulfur contents are determined beforehand and those of thereference solutions are corrected appropriately.Use two background points for each element (on the right and left

24、of the Klradiation). Suitable backgroundpoints are provided by modern spectrometer software.Recommended settings for voltage and current can be found in table 2. A measurement time of 40 seconds hasproved satisfactory.Table 2: Test parametersX-ray fluorescence Wavelength, Voltage, Current,radiation

25、in nm in kV in mAV-Ka0,250 5 50 60Ni-Ka0,165 8 50 60S-Ka0,537 3 30 100Plot the calibration graph for the analyte (i) using corrected intensities, I(i,corr), calculated as follows:+=1001(S)s)(i,gem)(i,corr)(i,KII.(1)whereI(i,gem)is the measured intensity of the analyte (i);a(i,s)is a correction facto

26、r for compensating for the influence of sulfur on the measured intensity of theanalyte (i);K(S)is the percentage by mass of sulfur.NumberVanadium content, Nickel content, Sulfur content,in mg/kg in mg/kg as a percentage by mass100025053 50 50 1,04 50 50 2,05 50 50 3,06 5 2,5 0,57 10 5 1,58 20 10 0,2

27、9 100 20 0,010 200 30 0,811 500 100 0,5Page 4DIN 51790-7 : 2002-01The analytical function derived from this calibration for determining the proportion by mass (vanadium andnickel) and percentage by mass (sulfur) of the analyte, K(i), is given by:+=1001Ssi,gem)(i,(i)(i)(i)KIbK.(2)wherea(i)is the inte

28、rcept on the vertical axis;b(i)is the slope of the analytical function.Using the software, calculate the correction factor, a(i,s), by the fundamental parameter method as a functionof the sulfur content for vanadium, nickel and sulfur. Since the contents of vanadium and nickel are in the mg/kgrange,

29、 no correction is necessary for these elements.Check the calibration graph at least every six months.10 ProcedureTransfer an adequate amount of the sample to be analysed to a test beaker, heating high-viscosity samples to80 C beforehand. Expose the sample to the radiation from the X-ray tube and det

30、ermine the net count ratesof the V-Ka, Ni-Kaand S-Karadiation using the analysis program referred to in clause 9.11 EvaluationDetermine the content of vanadium, nickel or sulfur in the sample using a computer (modern computers andsoftware will complete the measurement as in clause 10 and the evaluat

31、ion as in the present clause almostsimultaneously). If the content of vanadium, nickel or sulfur is found to exceed the concentration range givenin table 1, dilute the sample with an appropriate amount of paraffin. Prepare a homogeneous solution by stirringand heating to not more than 80 C (possibly

32、 diluting beforehand with xylene or 2-ethylhexanoic acid to makedissolving the sample easier). After cooling to ambient temperature, reanalyse the sample so prepared asdescribed in clause 10.12 Expression of resultsMaking reference to this standard, report the vanadium and nickel contents of the sam

33、ple in mg/kg, to onedecimal place, taking due account of DIN 1333 when rounding.Making reference to this standard, report the sulfur content as a percentage by mass, to three significant places.13 Precision(cf. DIN EN ISO 4259)The specifications below apply to the products referred in clause 1 in th

34、e concentration ranges specified intable 1. The precision data were determined using equipment as specified in clause 5 and the equipmentsettings in accordance with table 2.Repeatability limit(same operator, same equipment)If two results are obtained under repeatability conditions, both results shal

35、l be considered acceptable and inconformity with this standard if they differ by no more than the value given in table 3.Reproducibility limit(different operators, different equipment)If two separate laboratories each obtain a result under reproducibility conditions, both results shall be con-sidere

36、d acceptable and in conformity with this standard if they differ by no more than the value given in table 3.Page 5DIN 51790-7 : 2002-01Table 3: Repeatability and reproducibility limits for vanadium and nickelTable 4: Repeatability and reproducibility limits for sulfurElementRepeatability limit, Repr

37、oducibility limit,in mg/kg in mg/kgVanadiumUp to 10 mg/kg 1 2Over 10 mg/kg up to 30 mg/kg 2 3Over 30 mg/kg up to 500 mg/kg x . 0,05 x . 0,10NickelUp to 10 mg/kg 1 2Over 10 mg/kg up to 30 mg/kg 2 3Over 30 mg/kg up to 100 mg/kg x . 0,04 x . 0,08NOTE: x represents the measured value.Sulfur contentRepeatability limit, Reproducibility limit,as a percentage as a percentageSulfur0,0010 % to 0,0050 % x . 0,40 x . 0,60Over 0,0050 % up to 0,0150 % x . 0,20 x . 0,40Over 0,0150 % up to 3,00 % x . 0,05 x . 0,16NOTE: x represents the measured value.