1、(EN EN+27b27-b 93 m 3404587 0047397 55T m EUROPEAN STANDARD EN 27627-6 NORME EUROPENNE d EUROPISCHE NORM April 1993 UM: 669.018.25 : 620.1 : 543.422 : 546.76 Descriptors: Powder metallurgy, hard metals, chemical analysis, determination of content, transition metals, chromium, atomic absorption spect
2、rophotometry English version Hardmetals - Chemical analysis by flame atomic absorption spectrometry - Part 6 : Determination of chromium in contents from 0,Ol to 2 % (m/m) (IS0 7627-6 1985) Mtaux-durs - Analyse chimique par spectromtrie dabsorption atomique dans la flamme - Partie 6: Dosage du chrom
3、 des teneurs comprises entre 0,Ol et 2 % (m/m) Hartmetalle - Chemische Analyse durch Flammenatomabsorptionsspektrometrie - Ri1 6: Bestimmung des Chromgehaltes von 0,Ol bis 2 % (m/m) (IS0 7627-6 : 1985) (IS0 7627-6 : 1985) This European Standard was approved by CEN on 1993-04-02. CEN members are boun
4、d to comply with the CENKENELEC Internal Regulations 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 standards may be obtained on application to the Cen
5、tral Secretariat or to any CEN member. This European Standard exists 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
6、 the official versions. CEN members are the national standards bodies of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CEN European Committee for Standardization Comit Eu
7、ropen de Normalisation Europisches Komitee fr Normung Central Secretariat: rue de Stassart 36, B- 1050 Brussels O 1993 Copyright reserved to CEN members Ref. No. EN 27627-6 : 1993 E CEN EN*Z?b27-b 93 3404589 0047398 49b = Page 2 EN 27627-6 : 1993 Foreword In 1992, IS0 7627-6 : 1985 Hardmetals - Chem
8、ical analysis byjlam atomic absorption spectromet?y - Part 6: Determination of chromium in contents from 0,Ol to 2 % (mim) was submitted to the CEN Primary Questionnnaire procedure. Following the positive result of the CEN/CS Proposal IS0 7627-6 : 1985 was submitted to the CEN Formal Vote. The resul
9、t of the Formal Vote was positive. 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 1993, and conflicting national standards shall be withdrawn at the latest by October 1993. According to t
10、he Internal Regulations of CENICENELEC, the following countries are bound to implement this European Standard: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CEN EN+27b27-
11、b 93 3404589 0047399 322 Test portion Content I 9 0.01 to 0,l O, 500 O, 1 to 0,5 0.500 0,1 to 0,s 0.100 0.5 to2 0,100 Page 3 EN 27627-6 : 1993 Dilution I Reciprocal sensitivity. Linear for 1 YO volume “) ! Oxidant Wavelength for the test portion11 absorption11 ml nm Cig/ml % 100 N2O 357,9 0,11 o to
12、0,12 500 N2O 357.9 0,11 O, 1 to 0,5 100 N2O 357.9 0,11 0.1 to 0,5 500 NZO 357,9 0.11 0.4 to 2 1 Scope and field of application This part of IS0 7627 specifies the method to be used for the determination of the chromium content of hardmetals within the range 0,Ol to 2 % (mim) by flame atomic absorpti
13、on spec- trometry. General requirements concerning the field of application, prin- ciple, interfering elements, apparatus, sampling and test report are given in IS0 7627/1. 2 Reference IS0 76271 1, Hardmetals - Chemicat analysis by flame atomic absorption spectrometry - Part 1 : General requirements
14、. 3 Reagents 3.1 Potassium pyrosuifate. 3.2 Perchloric acid, e 1,M or 1,67 glml. 3.3 Ammonium citrate, solution. Dissolve 100 g of citric acid in 1 500 ml of water and add 400 ml of ammonia solution (e 0,91 glmli. 3.4 Hydrogen peroxide, 30 % (mlm). 3.5 containing 1,OOO g of chromium per litre. High
15、purity stock solution, for calibration purposes, NOTE - This value is understood to establish a maximum limit of 1,ooO 5 g and a minimum limit of 0,999 5 g. 4 Procedure 4.1 Test portion Weigh, to the nearest 0,001 g, the relevant amount of the test sample indicated in table 1. Transfer it to a 100 m
16、l conical flask (preferably of quartz). NOTE - In this special case, the sample shall pass a 0,18 mm sieve. 4.2 Dissolution of the test portion Add 5 g of the potassium pyrosulphate (3.11 and a few drops of the perchloric acid (3.2) to the beaker containing the test por- tion (4.11 and heat gently u
17、ntil the test portion is completely dissolved. Add 40 ml of the ammonium citrate solution (3.3), and about 0,5 ml of the hydrogen peroxide (3.4). Then transfer the solution to a 100 ml polypropylene one-mark volumetric flask and dilute to the mark. CEN EN*:27627-b 93 m 3404589 0047200 974 m Content
18、% (mim) from 0,Ol to 0,M over 0,2 to 2 Page 4 EN 27627-6 : 1993 Range % (m/rn) 0,012 0,O x (content) 4.3 Dilution volume Content % (mim) Prepare the relevant dilution volume for the analysis according to table 1 as follows : Round to the nearest % (mim) 4.3.1 Dilution volume 100 ml : use the solutio
19、n in 4.2. 4.3.2 Dilution volume 500 ml : transfer 20 ml of the solution in 4.2 to a 100 ml polypropylene one-mark volumetric flask and dilute to the mark. 4.4 Preparation of calibration and blank solutions 4.4.1 Prepare at least six solutions according to 4.2 with a matrix composition as similar as
20、possible to the test portion to be analysed, but without making up to volume. Then add in- creasing volumes of the properly diluted stock solution of chromium (3.5) according to the concentration range to be covered. Make UP to 100 ml and mix. 4.4.2 Also prepare calibration solutions with a diluted
21、matrix in accordance with 4.3 for dilution volumes of 500 ml, if necessary. 4.4.3 Prepare a blank solution (see4.4.1) without the addition of chromium. 4.5 Adjustment of the atomic absorption spectrometer SAFETY PRECAUTION : Follow the manufacturers recommendation on igniting and extinguishing the f
22、lame. Optimize the response of the instrument at the wavelength given (see table 1). Preheat the burner for about 5 min and then adjust the fuel and correct the burner to obtain maximum absorption while aspirating a calibration solution. Make sure that the absorbance reading is not drifting. Aspirat
23、e water and set the initial reading to zero absorbance. 4.6 Atomic absorbance measurements 4.6.1 Aspirate first the blank solution and then the calibration and test solutions consecutively and record the readings. Aspirate water between each solution. Make at least two measurements for each solution
24、. If a build-up of solids occurs on the burner slit, it will cause a decrease of sensitivity and must be removed. 4.6.2 Prepare a calibration curve by plotting the obtained ab- sorbance values of the calibration solutions corrected for the blank against the concentration, in milligrams per litre, of
25、 chromium. 4.6.3 Convert the absorbance values of the test solutions cor- rected for the blank to milligrams of chromium per litre by means of the calibration curve. 5 Expression of results 5.1 Calculation The chromium content, expressed as a percentage by mass, is given by the formula cx v 104 x m
26、where c is the concentration, in milligrams per litre, of chromium in the test solution; V is the dilution volume, in millilitres; m is the mass, in grams, of the test portion. 5.2 Permissible tolerances The deviations between three independent determinations shall not exceed the values shown in tab
27、le 2. Table 2 - Permissible tolerances 5.3 Final result Report the arithmetical mean of acceptable determinations rounded to the nearest value as shown in table 3. from 0.01 to 0,20 I over 0,20 to 2 I 0.01 0,m If the chromium content is below 0.01 % (m/rni, report it as less than 0.01 % irn/mi. (EN
28、ENx27627-6 93 m 3404587 0047203 800 m Page 5 EN 27627-6 : 1993 Annex ZA (normative) Normative references to international publications with their relevant European publications This European Standard incorporates by dated or undated reference, provisions from other publications. These normative refe
29、rences 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 this European Standard only when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies (including amendments). Publication Year Title EN/HD - Year IS0 7627-1 Hardmetals - Chemical analysis by flame EN 27627-1 atomic absorption spectrometry - Part 1 : General requirements
