1、CEN EN*(cLO*L8 89 340V589 OOOOi226 8 EUROPEAN STANDARD EN 10 188 NORME EUROPEENE EUROPAISCHE NORM May 1989 UDC 669.1 :620.1:546.76:543.422 Key words: Iron and steel products, steels, cast irons, chemical analysis, chromium, atomic absorption spectrometry, flame photometry English version Chemical an
2、alysis of ferrous materials. Determination of chromium in steels and irons. Flame atomic absorption spectrometic method Analyse chimique des materiaux siderurgiques. Dosage du chrome dans Bestimmung von Chrom in Stahl und les aciers et les fontes. Methode par Eisen. Chemische Analyse von Eisenwerkst
3、o en. spectrometrie dabsorption atomique Flammenatomabsorptionsspektrometrisches dans la flamme Verfahren This European Standard was accepted by CEN on 1989-05-15. GEN members are bound to comply with the requirements of the CENICENELEC Com- mon Rules which stipulate the conditions for giving this E
4、uropean Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN Central Secretariat or to any CEN member. This European Standard exists in three official versions (
5、English, French, German). A version in any other language may be translation under the responsibility of a CEN member into its own language and notified to CEN Central Secretariat has the same status as the official versions. CEN members are the national standards organizations of Austria, Belgium,
6、Den- mark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxemburg, Netherlands Norway, Portugal Spain, Sweden, Switzerland and United Kingdom. CEN European Committee for standardization Comite Europben de Normalisation Europisches Komitee fr Nornung Central Secretariat: rue Brederode 2
7、, 8-1000 Brussels (cl CEN 198.9 Copyright reserved to all CEN members Ref. No. EM 10 1881989 E Official Photocopy CEN EN*LO*LBB 87 II 3LiO4589 0000227 T m EN 10 188 Page 2 Brief Bistory This European Standard takes over the contents of EURONORM 188-87 “Chemical analysis of ferrous materials - Determ
8、ination of chromium in steels and irons - Flame atomic absorption spectrometric method“ prepared by ECISS/TC 20 Methods of chemical analysis” the secretariat of which is allocated to the Dansk Standardiseringsrad (DS). It was submitted to the CEN Formal Vote following the decision of the Coordinatin
9、g Commission (COCOR) of the European Committee for Iron and Steel Standardization on 1987-11-24125. According to the Common CEN/CENELEC Rules, following countries are bound to implement this European Standard: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxe
10、mburg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CEN EN*LO*LBB 89 m 3404587 O000228 L m EN i0 i88 Page 3 . Chemical analysis of ferrous materials Determination of chromium in steels and irons Flame atomic absorption spectrometric method CONTENTS Pale 1 SCOPE AND F
11、IELD OF APPLICATION . 2 2 REFERENCES 2 3 PrnCIPLE 2 4 REAGENIS . 2 5 APPARATUS 2 6 SAWLING . 3 7 PROCEDURE . 3 7.1 Test portion 3 7.2 Blink test . 3 7.3 Dtterminrtioo 3 7.4 Estiblishwot of tk alibritioo grw 4 8 EXPRESSION OF RESULTS i . 5 9 TEST REPORT . 5 ANNEX: Precision dita . 6 9 EN :O ?88 Page
12、4 I SCOPE AND FIELD OF APPLICAlOlri This Wpean standard qxafk a method fct. the detamiration of chmium in steels and jrws by mears of fiame atomic atzxxpim speca73metry. The method is applicable to non-allo) and low-allo! steels and irons hith chromium contents o 001 to 2.0 0. I m,m i !bee Anne) 2 R
13、EFERENCES turonorm I8 - Selection and preparation of samples and test pieces ior steel and iron and steel products. Information Circular No 8 - Recommendations for the drafiing ot standard methods of analysis employing flame atomic absorption spectromets for the chernical analysis of iron and steel.
14、 Information Circular No 9 - Operational guidelines for the application ol flame atomic absorption spectrometry in standard methods or the chemical analysis of iron and steel. 3 PRINCIPLE Dissolution oia test portion with hydrochloric acid followed b) oxidation with nitric acid. Filtration and ignit
15、ion of the acid insoluble residue. Removal of silica with hydrofluonc acid Fusion of the residue with potassium hydrogen sul. phate. extracrion of the melt in acid and addition of the extract to the resewed filtrate. Determination of the chromium by means of the spec- trometric measurement of the at
16、omic absorption of the 35 7.8 7 nm line emitted by a chromium hollow cathode lamp when the solution is nebulized into a nitrous oxide acetylene flame. 4 REAGENTS During the analysis. ux only reagents of ncognized analy- tical reagent quality and having a very low chromium content. and only distilled
17、 water or water of equivalent purity. 4.1 Iron. of high punty, with a chromium content C I CiBIB. 4.2 Potassium hydrogen sulphate (KHSO4). 4.3 Hydrochloric acid. p I. 19 g/ml approximately. ( I2 mol/l approximately). 4.4 Nitric acid. p 1.40 g/ml approximately, (14 mol/l approximately). 3404587 00002
18、29 3 9 4.5 Sulphuric acid. p I 84 elml approximate! 1 13 moi approximatel) b 4.6 Hbdrotluoric dad. P 1.15 glml approtrmatei) I 20 mol; I approximatel) 4.7 Sulphuric acid. p 1.84 gim1 approximatel). diluted 1 I+! (L.V). (4.5 molil approximatel). 4.8 Background solution Weigh IO g of iron (4.1 ) into
19、a I litre beaker Add IO 8 01 potassium hydrogen sulphate (4.2) and I50 ml ol hkdro- chloric acid (3.3) Heat gently until dissolved. then oxidize with 30 ml of nitric acid (4.3). added in small portions Allow to cool. transfer to a 250 mi volumetric flask. dilute !o the mark with water and mix. 4.9 C
20、hromium reference solution. corresponding to I rng of chromium per ml. Weigh 1.OOO g of high punty chromium metal (3 99.% (mim) pure). Transfer to a 250 mi beaker and dissolve in 40 ml of hydrochloric acid (4.3). Cool. transfer to a I O00 ml volumetric flask. dilute to the mark wirh water and mix. ,
21、 ,Vote: p equals the density. 5 APPARATUS Ordiwy iaboratory equipment and 5.1 Atomic absorption spectrometer: a chromium hollow cathode Imp: supplia of nitrous oxide and acetylene sufficiently pun to give a neady. clear ellcan flame. fret from water and oil and free fiom chromium. The atomic absorpt
22、ion spectrometer wd will be satisfactory fatter optimization according to 7.3.4. the limit of detection and chancteristic concentration are in reasonable agreement with the values given by the manulkturer and it meets the following performance rquimnts. 5. I. I Midrri ecirha The standard deviation o
23、f IO merainments of the ;ibsorbpnce of the most concmurted calibration solution shall not exceed I .5 %I of the mean absorbance. The standord deviation of IO masurcments of the atKortmce of the least concentrated calihtion solution (excluding the zero calibration solution) shall not exceed 0.5 X of
24、the mean absorbma of the most concentrated calibration solution. For example. if the top and bottom calibration solutions represent O. IO X and 0.02 Yn chromium in the sample. the CEN p EN* cai tbi (C) C haractenstic concentration - The charactenstic con- centration or chromium in a matra similar to
25、 the finai sample test solution shall k better than 0.25 pg/mi. Limit of detmion - The limit of detection of chromium in a matra similar to the final sample test solution shall be benet than 0.05 mi. Curve linearity - The slope of the calibration curve covering the top 20 o/o concentration range (ex
26、pressed as a change in absorbance) shail not be less than 0.7 ofthe value of slope for the bottom 20 % concentration range determined in the same way. For instruments with automatic standardization using only two falibration solutions. one king twice the concentration of the other. the acceptable cw
27、e linearity is limited to such an extent that the absorption of the lower calibration solution does not exceed 0.55 of the absorption of the higher calibration solution. 5.2 Ancillary equipment A strip chart recorder and/or digital dout devicc is recommended to evaluate the cntena in 5.1 and for dl
28、subsequent measurements. 6 SAMPLING Sampling sha k mod out in accordance with Eutonorni 18. 7 PROCEDURE 7.1 Test portion Weigh the mass (m) indicated below to the nearest 0.001 8: m-IgtlK 7.2 Blank test With erh analyticai run, carry out an uuhsb on 1 Went blank in parallel with the tcst ponion mipi
29、s, wing identicai reagenu. conditions. anaiytiai praadureJ uid dilutions throughout. 7.3 Determination 7,3.1 Prepurtioi of tk tut sdrtior Place the test ponion (7. I ) in a 250 ml baker. Add I5 mi of hydrochlonc acid (4.3). cover the beaker and heat gently EN 1C 188 Pige 5 until solvent action cease
30、s. Oxidize with 3 ml of nitnc acid (4.4) added dropwise and boil for I minute to remove oxides of nitrogen. Cool. dilute with about IS ml of water and filter through a pulp pad prepared from macerated filter paper. collecting the filtrate in a 100 mi volumetnc ilask Wash the filter with water. colle
31、cting the washings in the same 100 mi volumetnc flask. but taking care to 1eak.e sufficient room for the fusion extract of the acid insoluble residue. about 10 mi. to be added later. Reserve the filtrate Transfer the filter and residue to a smail platinum capsule or crucible. dry and ignite at as lo
32、w a temperature as possible until aii carbonaceous matter is removed and finally at about 800OC for at least I5 minutes. Cool. add 2 drops o sulphunc acid solution (4.7) and about 2 mi of hydroluonc acid (4.6). Evaporate to dryness. heat to about 800 C and cool. Add I g of potassium hydrogen sulphat
33、e (4.2 and fuse canfully until a clear melt is obtained. .Vote: For residues which contain chromium carbide. prolonged heaung may k necessary for complete fusion. The potassium hydrogen sulphate can be regenerated by aiiowing the melt to cool. adding 2 drops of dphunc acid solution (4.5) and repeati
34、ng the hion until the residue has dissolved. Cool and transfer the crucible and soiidified melt to a smail beaker, Add 10 mi of water and 2 ml of hydrochlonc acid (4.3) and heu aentiy until the solid has dissolved. Cool. add the extract to the reserved filtrate in the 100 mi volumetnc flask. dilute
35、to the mark with water and mix. This is the sample solution S. Set up the innniment p5 described in 7.3.3. Test the solution S a! wious approximite dilutions to obuin the dilution fMor D. tha! bruigs the solution near the midway of the OpUmum working ringe of the instnimc nt. e.g. 0.25 to 0.45 abmrk
36、nce units. Acnurtdy dilute the sampk solution S with water by the dilution haor D to okw the test solution N. Dilute the blank tcst solution (7.2) in the same way. Note; Vohimer of sample solution S ksr than 5 ml shail not be taken for dilution. 7.3.2 Preparation of tk dbritioi solution if the tut r
37、olubn N aver an rkodmce abovc 0.25. acumdy dilue the rtuidrrd chromium wWon (4.9) to 5, 10. IS, 20 ml thc rbon * zcock solution to 100mlvdrnnaricILiLu.MdCZSO*mt;Dmlofd solurion (4.8) to eich and dilutctothc mukwith water (D is the dilution of the sunple solution). $h .a ,stock Jolurion rpproximuay 6
38、00 timCs the dur. e -USh (5.1,2). u- 8 w. UUiSfCT o. If the test solution N ves UI rkorknce blow 0.25, prrpuc two solutions ach CO- 25 mi of brkground solution (4.8) per 100 ml. one con- 5 pg/mi of chromium. the other no ddsd duomiurn. U- these. a muh estimrte of the chromium in the test solution ca
39、n be nidt. Acnrritdy diiw the SMdUb chromium solution (4.9) to Ove 8 stock solution ofconcaiurtion 10 times the chromiwi kvd in the tat roQaion, as cstimued above. Wu a kirrtre, uuidcr O, 5. io, 15.20 ml of the chromium stock solution to 100 mi volumetric Mcr. Add 25 ml of brkground Won (4.8) to eac
40、h and dilute to the mark mth woter. CEN EN*10*188 89 340Li.587 0000231 1 The top standard shaii contain at lean sufficient chromium to give full scale deflection when using maxnum scale expansion. 7.3.3 Adjustment of atomic absorption spectropbotowter (5.1) Type of lamp: Wavelength: 357.87 nm. Rame:
41、 nitrous oxidelacetylene. Lamp current: follow manufacturers recommendations. Slit width: follow manufacturers recommendations. chromium hollow cathode. .Vole - The manufacturers recommendations should be closely followed and particular attention is drawn to the following safety points: (a) the expl
42、osive nature of acetylene. and nguhons con- cerning iu use: (b) the need to shield the eyes of the operator fiom UV radiation by means of tinted glass: (c) the need to keep the burner head clear of deposits. A badly clogged burner may caw a tiash beck; (d) the need to ensure that the liquid trap is
43、fuled with water. See also Information Circular No 9 - Appendix C. 7,3.4 Optimiutioi of te atomic absorptioa rpatroter settings FoUow the menufacnims instructions for pnpuinl the instrument for use. (Sa also Infonnation CircuLi No 9 - Appendix A). When the current to the lamp. the wavelength and the
44、 flow of gas have been adjusted and the burner lit. spray water until the indication has stabilized. Sei the abrotbencc duc to zero. Choose a damping setting or integration time to give a signai steady enough to fulfil the precision rsquimncnts (5. I. I ). Adjust the flame to k fuel-leui and thc kin
45、m Wt to about I cm below the ght pah. Spnyinl, rhtrnrdy, the high and zero calibration solutions, adjust the tlow 8nd burner position (horizontally, vmhily uid nwtionrlly) until the diffmnce in absorbntx krwoen the aiikoion solutions is at a mimum. Check that thc rgsnromerr U set on the requid mvclm
46、gth. Evaluate the criteria of 5. I. I to ensure that the innnunent ir suitable for the detcnnination. 7.3.5 Atomic absorption Pluureacots Set the scale expansion so that the top alibrotion soution gives nearly hull scale deflection. Aspirate. the alikuion solutions in ascending order npaitivcly unti
47、l erch pvcr the specified prkision ( 5, i, I ) thus showing thu the instrument has achieved stability. Select two calihtion solutions. one having an absorbente just lower than the test ponion solution and one just higher. Aspirate thesc first in a5mding order. then in descending order. with the test
48、 solution as the middle solution in each asc. measmg the absorbance in relation to water. Aspirate the complete range of calibration solutions again. It IS recognized that these procedures cannot be iollowed with automatic instruments which accept two calibration solutions only. In this case. it is
49、suggested that the two sandwiching solutions should not be used for the primar) calibration bur should k analyscd alternately with. the test solution. Spray a calibration solution at frequent intervais dunng the meosunment of a batch of determinations. Clean the burner if the results show loss of precision caused by clogging. obtain the net nuan absorbance of each calibration solution y subuacung the mean absorbnce of the zero calibration solution. Obtain the man obsotbpncc of the test solution and the mean absorb of the nagent blan
