1、UDC 621.892.2 : 665.765 : 620.1 : 543.426 DEUTSCHE NORM March 1994 Determination of additive elements content of I u bricants by wavelength-dispersive X-ray fluorescence spectrometry (XRS) DIN - 51 391. Part 2 Prfung von Schmierstoffen; Bestimmung des Gehaltes an Additivelementen; wellenlngendispers
2、ive Rntgenfluoreszenz-Analyse (RFA) Manganese octoate) 1 Mn-Ka Supersedes September 1978 edition. 0,2103 In keeping with current practice in standards published by the International Organization for Standardization (ISO), a comma has been used throughout as the decimal markel: 1 Scope and field of a
3、pplication This standard specifies a method, based on X-ray fluo- rescence spectrometry, by which the content of barium (Ba), zinc (Zn) or copper (Cu) present in mineral oils, synthetic oils and additives is determined. As the above elements are an oil-soluble part of the additives con- tained in lu
4、bricants, this method may also be employed to estimate the amount of these additives. lated. The metal content of the sample can be deter- mined, as a percentage by mass, from a calibration graph prepared on the basis of the solutions of the metal in question. The method is generally applicable to s
5、amples of any composition and irrespective of the type of metal com- pounds involved and of any other elements they con- tain. 2 Unit The unit in which the content is expressed is percent- age by mass. 3 Principle Ten parts by mass of the sample to be analysed and one part by mass of a reference sub
6、stance are mixed and exposed, in a test vessel, to the primary radiation of an X-ray tube. Table 1 lists the reference substances used for the determination of the individual metals and the types of radiation and the wavelengths used. The count rates of the X-ray fluorescence radiation thus excited
7、in the metal and reference substance are measured and the ratio of these count rates is calcu- 4 Apparatus In addition to standard laboratory apparatus, the follow- ing shall be used. (a) Wavelength-dispersive X-ray spectrometer (ci. DIN 51 418), capable of measuring the count rates of the types of
8、X-ray fluorescence radiation listed in table 1. To determine the barium, calcium, zinc and copper contents, the X-ray spectrometer shall have the characteristics listed in table 2. (b) Balance, with 0,l mg scale divisions. (c) Stirrer, capable of being heated. (d) 50 ml conical flasks (e.g. DIN 1238
9、0 - EE50 flasks). (e) Beakers (e.g. DIN 12331 beakers). Wavelength, in nm Type I Radiation Barium 1 Ba-LP, I 0,2567 Calcium Ca-Ka 0,3360 Zinc Zn-Ka 0,1436 i Copper Cu-Ka 0,1542 I Radiation I wa,mgth7 Cobalt octoate Co-Ka 0,1789 Cobalt octoate Co-Ka 01789 ) An oil-soluble titanium compound (Ti-Ka; 0,
10、2749 nm) may be used as an alternative reference substance. ) Copper octoate may be used as an alternative reference substance for zinc if a check has been made to ensure that the sample does not itself contain copper. The use of cobalt octoate enables zinc and copper to be determined without a prel
11、iminary test when they are both present. In the determination of zinc, the sulfur content will still be found to have a slight effect. Continued on pages 2 to 5. Beuth Verlag GmbH, Berlin, has the exclusive right of sale for German Standards (DIN-Normen). DIN 51 391 Part 2 Engl. Price group 6 03.96
12、Sales No. 0106 Page 2 DIN 51 391 Part 2 Analyser crystal Detector X-ray path Table 2: Characteristics of X-ray spectrometer Lithium fluoride Lithium fluoride Lithium fluoride (2d = 0,4028 nm) (2d = 0,4028 nm) Continuous flow proportional Continuous flow proportional Scintillation counter with counte
13、r with pulse height counter with pulse height analyser analyser Helium Helium Helium (2d = 0,4028 nm) pulse height analyser ComDonent I Barium I Calcium I Zincicopper X-ray tube Anode Voltage Current Rhodium, chromium ), scandium, molybdenum 50 kV 20 mA Rhodium, chromium, scandium, molybdenum 50 kV
14、10 mA Rhodium, chromium, scandium, molybdenum 50 kV 20 mA Collimator I Narrow I Narrow I Narrow 5 Reagents The following reagents shall be used. (a) Liquid paraffin (paraffinum perliquidum), as specified in DAB lo4). (b) Analytical grade xylene. (c) Barium, calcium, zinc and copper octoates5) or oth
15、er oil-soluble compounds of these metals with a known metal content for plotting the calibration graphs. (d) Manganese, tin, cobalt and copper octoates5) or other oil-soluble compounds of these metals for use as reference substances. Use only stable com- pounds; naphthenates have proved satisfactory
16、. If the reference substances still contain solids orig- inating from their preparation such as the corre- sponding oxides, purify them by dissolution in ligroin, filtration and evaporation of the solvent. (e) Stock solutions of barium, calcium, zinc or cop- per, to be prepared by dissolving suffici
17、ent barium, calcium, zinc or copper octoate in liquid paraffin to give 1 g of Ba, Ca or Zn, or 0,l g of Cu, in 100 g of each solution. (f) Reference solutions of manganese, tin, cobalt or copper, to be prepared by dissolving a sufficient amount of the octoate concerned in xylene to give 0,6 g of Mn,
18、 or 11,7 g of Sn, or 1 g of Co, or 1 g of Cu in 100 g of solution in each case. As an alterna- tive to xylene, liquid paraffin or a mixture of xylene or liquid paraffin may be used provided the stability has been checked. In clauses 7 and 8, these solu- tions are referred to as manganese, tin, cobal
19、t and copper solutions. . 6 Sampling See DIN 51 750 Parts 1 and 2. Dilute the appropriate stock solution with liquid paraffin, while stirring and heating to obtain barium, calcium or zinc reference solutions containing about 0,05, 0,10, 0,25, 0,510, 0,75 and 1,00 % by mass of Ba, Ca or Zn and a copp
20、er reference solution containing about 0,005, 0,01,0,02 and 0,05 % by mass of copper. Before using the reference solutions, ensure that they are at ambient temperature (18 to 28C). Z2 Test solutions 7.21 Add one part by mass of manganese solution to ten parts by mass (e.g. 20 g) of each barium refer
21、ence solution, and prepare a homogeneous solution by stir- ring and heating at not more than 80C. 7.2.2 Add one part by mass of tin solution to ten parts by mass of each calcium reference solution, and pre- pare a homogeneous solution by stirring and heating at not more than 80 “C. 7.2.3 Add one par
22、t by mass of cobalt solution (or alternatively one part by mass of copper solution) to ten parts by mass of each zinc reference solution and prepare a homogeneous solution by stirring and heat- ing at not more than 80 “C. Z2.4 Add one part by mass of cobalt solution to ten parts by mass of each copp
23、er reference solution, and prepare a homogeneous solution by stirring and heat- ing at not more than 80C. Z3 Measurement of count rates Prepare the test solutions as in subclause 7.2 and allow them to come to ambient temperature. Transfer them to test vessels and expose them successively to the pri-
24、 mary radiation of the X-ray tube. Determine the individ- ual elements as described in subclauses 7.3.1 to 7.3.4. 7 Plotting the calibration graphs M Reference solutions When preparing dilutions, weigh out the amounts required to three decimal places for Ba, Ca and Zn and to four decimal places for
25、Cu. 4, DAB 10: Deutsches Arzneibuch (German Pharmaco- poeia) (see page 4). 5, Information on sources of supply is obtainable from DIN-Bezugsquellen fr normgerechte Erzeugnisse im DIN Deutsches Institut fr Normung e.U, Burggrafen- Strae 6, D-10787 Berlin. DIN51391 Part2 Page3 Z3.1 Barium Measure the
26、count rates, In, and IMn, of the barium and manganese lines listed in table 1. Select a counting method which gives at least 400000 counts for the Mn-Ka line over the entire measurement period. Calculate the count rate ratio, R, using equation (1): Z3.2 Calcium Measure the count rates, I, and I, of
27、the calcium and tin lines listed in table I. Select a counting method which gives at least 400000 counts for the Sn-La, line over the entire measurement period. Calculate the count rate ratio, R, using equation (2): Z3.3 Zinc Measure the count rates, I, and I, (or I, and IC-), of the zinc and cobalt
28、 lines (or alternatively copper line) listed in table 1 and measure the background count rate, ZU,Zn, at 0,159 nm. Select a counting method which gives at least 75 O00 counts over the entire measurement period for the Co-Ka line (or the alterna- tive Cu-Ka line). Calculate the ratio of the net count
29、 rates using equa- tion (3): Z3.4 Copper Measure the count rates, IC“ and I, of the copper and cobalt lines listed in table 1 and the background count rate at 0,159 nm. Select a counting method which gives at least 75000 counts over the entire measurement period for the Co-Ka line. Calculate the rat
30、io of the net count rates using equa- tion (4): IC“ - h,cu IC, - I“,C“ %- (4) Z4 Calibration graphs Plot the count rate ratio, R or R, of the test solutions as a function of the corresponding barium, calcium, zinc or copper content or store the values in a com- puter. Check the calibration graphs at
31、 regular intervals of not more than six months. 8 Procedure 8.1 Add one part by mass of manganese solution for the barium determination or one part by mass of the tin solution for the calcium determination or one part by mass of cobalt solution (or alternatively copper solu- tion) for the zinc deter
32、mination or one part by mass of cobalt solution for the copper determination to ten parts by mass (e.g. 20 g) of the sample to be analysed. Prepare a homogeneous solution by stirring and heat- ing at not more than 80C. After allowing the sample to cool to ambient temperature, determine the count rat
33、e ratio, R or R , as described in subclause 7.3. 8.2 Use the calibration graph to determine the per- centage by mass of the barium, calcium, zinc or copper content of the sample from the measured count rate ratio, R or R,. If the sample content is greater than the maximum value on the calibration gr
34、aph, dilute the sample with liquid paraffin and repeat the measure- ment. 9 Expression of result Express the barium, calcium or zinc content, as a per- centage by mass, to the nearest 0,Ol %, and the copper content, to the nearest 0,001 %, making reference to this standard. Take DIN 1333 into accoun
35、t when round- ing. 10 Precision (Cf. DIN 51 848 Parts 1,2 and 3.) The following criteria apply only to the petroleum prod- ucts referred to in clause 1 of this standard (and con- tents of 0,05 to 1,OO % for barium, calcium and zinc and 0,005 to 0,05 % for copper). Repeatability limit (same operator,
36、 same apparatus) If two results are obtained under repeatability condi- tions by the same operator, both results shall be con- sidered acceptable and in conformity with this standard if they differ by no more than the value given in table 3. Reproducibility limit (different operators, different appa
37、ratus) If two separate laboratories each obtain a result under reproducibility conditions, both results shall be con- sidered acceptable and in conformity with this standard if they differ by no more than the value given in table 3. For ), see page I. Page 4 DIN 51 391 Part 2 Content Repeatability l
38、imit Reproducibility limit Calcium Element Barium Up to 0,50 Over 0,50 up to 1 ,O0 I Percentage by mass Up to 0,50 0,Ol 0,02 Over 0,50 up to 1 ,O0 0,02 0,04 0,oi 0,Ol Zinc Copper 0,02 0,03 Up to 0,50 0,005 0,Ol Over 0,50 up to 1 ,O0 0,Ol 0,02 0,005 to 0,05 0,001 0,002 Standards and other documents r
39、eferred to DIN 1333 DIN 12 331 DIN 12 380 DIN 51 41 8 DIN 51 750 Part 1 DIN 51 750 Part 2 DIN 51 848 Part 1 DIN 51 848 Part 2 DIN 51 848 Part 3 DAB 10 Presentation of numerical data Beakers for laboratory use Narrow mouth conical flasks for laboratory use Testing of petroleum products by X-ray spect
40、rometry: general Sampling of petroleum products; general Sampling of liquid petroleum products Testing of petroleum products; precision; terminology and its application to petroleum standards specifying requirements Testing of petroleum products; precision; designing interlaboratory tests Testing of
41、 petroleum products; precision; calculation of repeatability and reproducibility data Deutsches Arzneibuch, 10th edition, 1991. Obtainable from Deutscher Apotheker-Verlag, Stuttgart, and Govi-Verlag GrnbH, FranMurtMain Other relevant standards DIN 1310 DIN 32 625 Composition of gaseous, liquid and s
42、olid mixtures; concepts and symbols Quantities and units used in chemistry; amount of substance and derived quantities; terminology Previous edition DIN 51 391 Part 2: 09.78. Amendments The following amendments ave been made to the Sel: ?mber 1978 edition. (a) The determination of copper has been in
43、troduced. (b) Cobalt octoate has been specified as a reference substance for the determination of zinc. (c) The specification of the X-ray tube in table 2 has been amended. (d) The use of naphthenates as reference substances has been recommended. (e) The standard has been revised in form and substan
44、ce to take into account the specifications of DIN 1310 and the DIN 820 series of standards. References to other standards have been updated. DIN 51 391 Part 2 Page 5 Explanatory notes This standard has been prepared by Technical Committee Rntgenfluoreszenz-Analyse in collaboration with Technical Com
45、mittee Prfung von Schmierlen, sonstigen Olen and Paraffinen of the Fachausschu Minerall- und Brennstoff- normung of the Normenausschu Materialprfung (Materials Testing Standards Committee). A new reference substance was required since copper, which was formerly used as a reference substance for zinc
46、, has been in use in some additives for a number of years. Interlaboratory tests showed cobalt octoate, which has the advantage of being suitable for use as a reference substance for the determination of copper, to be satisfactory. Since the copper standard previously used allows zinc to be determin
47、ed with very high precision and has proved to be highly satisfactory, it has been retained as an alternative substance for cases where the samples are free of cop- per. The data on precision are based on a statistical evaluation of the results of interlaboratory tests commissioned by the Fachausschu Minerall- und Brennst0 ffnormung. International Patent Classification G O1 N 033/30 C 10 M 129/40
