1、ICS 75.160.20Prfung von Minerallen und Brennstoffen Bestimmung desSchwefelgehaltes (Gesamtschwefel) Teil 3: Verbrennung nachSchniger, Thorin-Sulfonazo-III-TitrationIn keeping with current practice in standards published by the International Organization for Standardization(ISO), a comma has been use
2、d throughout as the decimal marker.Ref. No. DIN 51400-3 : 2001-06English price group 06 Sales No. 010604.03DEUTSCHE NORM June 200151400-3Continued on pages 2 to 6. No part of this translation may be reproduced without the prior permission ofDIN Deutsches Institut fr Normung e. V., Berlin. Beuth Verl
3、ag GmbH, 10772 Berlin, Germany,has the exclusive right of sale for German Standards (DIN-Normen).Translation by DIN-Sprachendienst.In case of doubt, the German-language original should be consulted as the authoritative text.Determining the total sulfur content of petroleumproducts by the Schniger co
4、mbustion methodand thorin or sulfonazo III titrationSupersedesFebruary 1978 edition.All dimensions are in millimetres.ForewordThis standard has been prepared by Technical Committee Prfung von flssigen Kraftstoffen und Heizlenof the Fachausschuss Minerall- und Brennstoffnormung of the Normenausschuss
5、 Materialprfung(Materials Testing Standards Committee).AmendmentsThis standard differs from the February 1978 edition in that it has been revised in form and substance andreferences have been updated.Previous editionsDIN 51400: 1963-08; DIN 51400-3: 1978-02.1 ScopeThis standard specifies a method of
6、 determining the total sulfur content of petroleum products having aninitial boiling point of over 200 C, and of gas oil, fuel oil, bitumen, lubricating oils, extracts and paraffinscontaining more than 0,2 % (m/m) of sulfur. The method described is unsuitable for analysing doped oilscontaining calci
7、um, barium or metal-organic additives and for products containing phosphorus, where thevalues obtained will be too high. However, the method is insensitive to the presence of chlorides or nitrates.2 Normative referencesThis standard incorporates, by dated or undated reference, provisions from other
8、publications. Thesenormative references are cited at the appropriate places in the text, and the titles of the publications 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 rev
9、ision. For undated references, thelatest edition of the publication referred to applies.DIN 12242 Conical ground joints on laboratory glassware Dimensions and tolerancesDIN 12380 Narrow mouth conical flasks for laboratory useDIN 51400-1 Determination of total sulfur content of mineral oils and fuels
10、 General principlesDIN EN ISO 4259 Petroleum products Determination and application of precision data in relation tomethods of test (ISO 4259 : 1992 + Corr 1 : 1993)Page 2DIN 51400-3 : 2001-063 PrincipleThe combustion products of burning a sample in an oxygen atmosphere in a conical flask are absorb
11、ed in ahydrogen peroxide solution and the sulfate ions are determined volumetrically by titration using thorin, thorinand methylene blue or sulfonazo III.4 DesignationDesignation of the method of determining the total sulfur content by Schniger combustion and thorin orsulfonazo III titration:DIN 514
12、00-035 ApparatusIn addition to standard laboratory equipment, the following shall be used.5.1 Analytical apparatus, consisting of a DIN 12380-EE 500 conical flask and a DIN 12242 glass stopperhaving an NS 29/32 conical joint. The rim of the mouth should be widened to form a collar, and a platinum wi
13、reabout 0,7 mm in diameter with a platinum gauze assembly attached to its ends shall be sealed into the stopper(see figure 1). When the flask is sealed, the assembly shall be centrally situated immediately above the bottomof the flask.5.2 Balance, capable of being read to an accuracy of 0,000 1 g.5.
14、3 Dry, sulfur-free cotton wool.5.4 35 mm 3 mm ignition strips, made of filter paper1).5.5 Sample supports, made of filter paper (see figure 2)1).5.6 10 ml microburette, having 0,01 ml or 0,02 ml scale intervals.5.7 Compressed oxygen cylinder, fitted with a pressure regulator, a flexible hose and a g
15、lass tube forintroducing the oxygen into the conical flask.5.8 Platinum gauze assembly (see figure 3)1).5.9 Burner, providing a sulfur-free ignition flame, preferably a spirit flame.1) Information on sources of supply is obtainable from Fachausschuss Minerall- und Brennstoffnormung,Kapstadtring 2, 2
16、2297 Hamburg, Germany.Figure 1: Schniger combustion apparatusGlass stopperConical flaskPlatinum wirePlatinum gauze assemblyPage 3DIN 51400-3 : 2001-06Figure 3: Platinum gauze assembly6 ReagentsUnless otherwise specified, analytical grade reagents shall be used and the solutions used shall be aqueous
17、.The water used shall be distilled or fully demineralized by ion exchange.6.1 3% (m/m) hydrogen peroxide solution.6.2 2-propanol (isopropyl alcohol), C2H8O.6.3 0,2 % (m/m) thorin indicator solution.6.4 0,025 % (m/m) methylene blue solution.6.5 Sulfonazo III indicator solution (tetrasodium salt of 1,
18、8-dihydroxy-2,7-bis(2-sulfophenylazo)-3,6-naphthalenedisulfonic acid), prepared by dissolving 4 g of potassium acetate and 0,2 g of sulfonazo III in 100 mlof water.The indicator solutions shall be stored in quartz glass bottles.6.6 0,01 mol/l barium perchlorate solution, prepared bya) dissolving 1,7
19、 g of barium perchlorate in 200 ml of water, adjusting the pH value to 3,5 with perchloricacid and diluting to 1 000 ml with 2-propanolorb) adding 1,7 g of 60 % (m/m) perchloric acid (of density 1,54 g/ml) and 100 ml of water to 0,987 g of bariumcarbonate, transferring the solution to a 1 l volumetr
20、ic flask after the barium carbonate has completelydissolved (without heating), rinsing with 100 ml of water, adjusting to a pH value of 3,5 with perchloric acid,making the solution almost up to the mark with 2-propanol, mixing thoroughly, checking the pH value againand then making up to the mark wit
21、h 2-propanol.Standardize these solutions with 0,01 mol/l sulfuric acid, H2SO4. 1 ml of these barium perchlorate solutions isequivalent to 0,16 mg of sulfur.Figure 2: Filter paper sample supportFoldIgnition stripPlatinum wirePlatinum gauze assembly3 to 4Page 4DIN 51400-3 : 2001-067 Preparation7.1 Sam
22、ple weighing7.1.1 Cotton wool sample support for liquidsWedge a loose swab of cotton wool together with a filter paper ignition strip between the platinum gauzes (seefigure 3) so that about 2/3 of the space is filled (see figure 4), ensuring that the ignition strip projects about20 mm out of the gau
23、ze assembly and is directed upwards at an angle. Weigh the glass stopper, platinum gauzeassembly, cotton wool and ignition strip to an accuracy of 0,000 1 g. Without removing the assembly from theweighing cabinet, apply 30 mg to 70 mg of the sample liquid dropwise to the cotton wool as close as poss
24、ibleto the ignition strip and then reweigh, ensuring that the liquid is absorbed by the cotton wool.Figure 4: Ignition assembly for liquids7.1.2 Filter paper sample support for solidsShape the filter paper (see figure 2) into a channel, place it on the balance pan with the hollow side up and weighit
25、 to an accuracy of 0,000 1 g. Without removing it from the weighing cabinet, transfer 30 mg to 70 mg of thesample in small portions to the hollow side and reweigh. Then fold or roll the corners of the sample supporttogether and place it and the sample in the platinum gauze assembly with the ignition
26、 strip projecting about20 mm out of the assembly.7.2 Preparation of flaskPour 20 ml of hydrogen peroxide solution into the flask and lower the glass oxygen inlet tube into the latter,ensuring that it is not immersed in the absorption liquid, and then pass a gentle stream of oxygen through theflask f
27、or one minute.Safety precautionsa) Before use, carefully flush out the combustion flask with oil-free compressed air to ensure that it doesnot contain any organic solvents.b) Check the flask for damage before use and discard it if there are any scratches or cracks.c) Perform combustion behind a prot
28、ective Plexiglas partition.d) Allow the combustion flask to cool behind the protective Plexiglas partition for at least five minutes aftercombustion.8 Procedure8.1 CombustionRemove the glass stopper and weighed sample from the balance, ignite the ignition strip with a small flame andimmediately inse
29、rt the stopper into the oxygen-filled flask. Gently agitate the flask to improve the combustionin the oxygen atmosphere. Hold the stopper down firmly with the thumb since a slight overpressure may occurwhen combustion starts. After combustion, which will last no more than three seconds, allow the fl
30、ask to coolfor about five minutes and then shake it vigorously for two minutes to ensure that all the combustion productsare absorbed by the absorption liquid. Check that, after shaking, gases and fumes can no longer be seen in theflask.8.2 Determining the sulfate contentMeasure out 80 ml of 2-propa
31、nol into a measuring cylinder and transfer part of it to the collar of the flask mouth,carefully open the flask by removing the stopper, and then rinse the latter and the flask mouth with 2-propanol.The contents of the flask will then consist of 20 ml of absorption solution and 80 ml of 2-propanol.A
32、dd two drops of thorin indicator solution and two to four drops of methylene blue solution, or instead of theindicator solution add two to four drops of sulfonazo III indicator solution. If necessary, the ratio of thorinsolution to methylene blue solution may be altered by the operator. Then titrate
33、 with barium perchlorateIgnition stripCotton woolPlatinum gauze assemblyPage 5DIN 51400-3 : 2001-06solution. The end point is the first visible colour change from yellow to pink (if thorin solution alone is used) orfrom green to purple/grey (if thorin and methylene blue are used) or from blue/violet
34、 to blue/green (if sulfonazoIII indicator is used). During the titration, mix the flask contents well, preferably using a magnetic stirrer.NOTE: The thorin end point is very difficult to detect with certain types of lighting, particularly fluorescentlighting or direct sunlight, but good results are
35、obtained with a daylight lamp.The colour change can easily be detected photometrically at a wavelength of 520 nm.9 Blank testDetermine the blank value using sulfur-free oil.10 EvaluationCalculate the sulfur content, w(S), as a percentage by mass, using equation (1):(1)whereV0is the volume of barium
36、perchlorate solution used to titrate the blank solution, in ml;V1is the volume of barium perchlorate solution used for titration, in ml;t is the strength of the barium perchlorate solution;mEis the initial sample mass, in g;0,16 is the mass of sulfur equivalent to 1 ml of 0,01 mol/l barium perchlora
37、te solution, in mg.11 Expression of resultsTaking due account of DIN 51400-1, the sulfur content of the sample, w(S), shall be reported as a percentageby mass, to two decimal places, reference being made to this standard.12 Precision(cf. DIN EN ISO 4259)The following criteria shall be used to assess
38、 the reliability of results.Repeatability limit(same operator, same equipment)If two results are obtained under repeatability conditions by the same operator, both results shall be consideredacceptable and in conformity with this standard if they differ by no more than the value specified in table 1
39、.Reproducibility limit(different operators, different equipment)If two separate laboratories each obtain a result under reproducibility conditions, both results shall beconsidered acceptable and in conformity with this standard if they differ by no more than the value specifiedin table 1.Table 1: Re
40、peatability and reproducibility limits(values given as percentages by mass)()E)(m,tVVSw=1016001SulfurcontentRepeatabilitylimitReproducibilitylimitovertotoPage 6DIN 51400-3 : 2001-06Other relevant standardsDIN 51400-2 Determining the total sulfur content of petroleum products by the Grote-Krekelercom
41、bustion methodDIN 51400-4 Determining the total sulfur content of petroleum products by the Lingener combustionmethodDIN 51400-6 Determining the total sulfur content of mineral oils and fuels by X-ray fluorescence analysisDIN EN 24260 Petroleum products and hydrocarbons Determination of sulfur content Wickboldcombustion method (ISO 4260 : 1987)DIN EN ISO 8754 Petroleum products Determination of sulfur content of petroleum products Energy-dispersive X-ray fluorescence method (ISO 8754 : 1992)
