1、BRITISH STANDARDBS EN14940-2:2006Copper and copper alloys Determination of chromium content Part 2: FAAS methodThe European Standard EN 14940-2:2006 has the status of a British StandardICS 77.120.30g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g5
2、9g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58BS EN 14940-2:2006This British Standard was published under the authority of the Standards Policy and Strategy Committee on 31 August 2006 BSI 2006ISBN 0 580 49068 8National forewordThis British Standar
3、d is the official English language version of EN 14940-2:2006. The UK participation in its preparation was entrusted to Technical Committee NFE/34, Copper and copper alloys, which has the responsibility to: A list of organizations represented on this committee can be obtained on request to its secre
4、tary.Cross-referencesThe British Standards which implement international or European publications referred to in this document may be found in the BSI Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogu
5、e or of British Standards Online.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. aid enquirers to understand the t
6、ext; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep UK interests informed; monitor related international and European developments and promulgate them in the UK.Summary of pagesThis document comprises a front cover,
7、an inside front cover, the EN title page, pages 2 to 11 and a back cover.The BSI copyright notice displayed in this document indicates when the document was last issued.Amendments issued since publicationAmd. No. Date CommentsEUROPEAN STANDARDNORME EUROPENNEEUROPISCHE NORMEN 14940-2June 2006ICS 77.1
8、20.30English VersionCopper and copper alloys - Determination of chromium content -Part 2: FAAS methodCuivre et alliages de cuivre - Dosage du chrome - Partie 2 :Mthode par spectromtrie dabsorption atomique dans laflamme (SAAF)Kupfer und Kupferlegierungen - Bestimmung desCobaltgehaltes -Flammenatomab
9、sorptionsspektrometrisches Verfahren(FAAS)This European Standard was approved by CEN on 15 May 2006.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard without any alteration. Up-t
10、o-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the Central 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 translationunder th
11、e responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the officialversions.CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,Germany, Greece, Hungary, Iceland, I
12、reland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania,Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMIT EUROPEN DE NORMALISATIONEUROPISCHES KOMITEE FR NORMUNGManagement Centre: rue de Stassart,
13、36 B-1050 Brussels 2006 CEN All rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 14940-2:2006: EEN 14940-2:2006 (E) 2 Contents Page Foreword3 1 Scope 4 2 Normative references 4 3 Principle4 4 Reagents and materials 4 5 Apparatus .5 6 Sampling
14、.5 7 Procedure .5 8 Expression of results 8 9 Precision.9 10 Test report 10 Bibliography11 EN 14940-2:2006 (E) 3 Foreword This document (EN 14940-2:2006) has been prepared by Technical Committee CEN/TC 133 “Copper and copper alloys”, the secretariat of which is held by DIN. This European Standard sh
15、all be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by December 2006, and conflicting national standards shall be withdrawn at the latest by December 2006. Within its programme of work, Technical Committee CEN/TC 133 requested C
16、EN/TC 133/WG 10 “Methods of analysis“ to prepare the following standard: EN 14940-2, Copper and copper alloys Determination of chromium content Part 2: FAAS method This is one of two parts of the standard for the determination of chromium content in copper and copper alloys. The other part is: prEN
17、14940-1, Copper and copper alloys Determination of chromium content Part 1: Titrimetric method According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Cyprus, Czech Republic, D
18、enmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EN 14940-2:2006 (E) 4 1 Scope This part of this European Stand
19、ard specifies a flame atomic absorption spectrometric method (FAAS) for the determination of the chromium content of copper and copper alloys in the form of unwrought, wrought and cast products. The method is applicable to products having chromium mass fractions between 0,010 % and 2,0 %. 2 Normativ
20、e references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 1811-1, Copper and copper alloys
21、 Selection and preparation of samples for chemical analysis Part 1: Sampling of cast unwrought products ISO 1811-2, Copper and copper alloys Selection and preparation of samples for chemical analysis Part 2: Sampling of wrought products and castings NOTE Informative references to documents used in t
22、he preparation of this standard, and cited at the appropriate places in the text, are listed in the Bibliography. 3 Principle Dissolution of a test portion in nitric acid and digestion in sulphuric acid followed, after suitable dilution, by aspira-tion into an air-acetylene or into a nitrous oxide-a
23、cetylene flame of an atomic absorption spectrometer. Measure-ment of the absorption of the 357,9 nm line emitted by a chromium hollow-cathode lamp. 4 Reagents and materials 4.1 General During the analysis use only reagents of recognised analytical grade and only distilled water or water of equivalen
24、t purity. 4.2 Sulphuric acid, H2SO4( = 1,84 g/ml). 4.3 Hydrogen peroxide, H2O230 % (mass fraction) solution. 4.4 Nitric acid, HNO3( = 1,40 g/ml). 4.5 Nitric acid solution, 1 + 1 Dilute 500 ml of nitric acid (4.4) in 500 ml of water. 4.6 Hydrofluoric acid, HF ( = 1,13 g/ml). WARNING Hydrofluoric acid
25、 is a hazardous substance. Care shall be taken and it shall be used under an efficient fume hood. EN 14940-2:2006 (E) 5 4.7 Chromium stock solution, 0,500 g/l Cr Weigh 1,414 2 g of potassium dichromate (K2Cr2O7 99,9 %), previously dried at 140 C and allowed to cool in a desiccator. Place in a 400 ml
26、 beaker and dissolve in about 20 ml of water. Add 5 ml of sulphuric acid (4.2) and, while cooling, cautiously add the hydrogen peroxide solution (4.3), adding an excess of about 2 ml after efferves-cence has ceased. Allow the solution to stand at ambient temperature until the yellow colour has compl
27、etely disappeared (several hours), then transfer the solution quantitatively into a 1 000 ml one-mark volumetric flask. Dilute to the mark with water and mix well. Prepare this solution immediately prior to use. 1 ml of this solution contains 0,500 mg of Cr. 4.8 Chromium standard solution, 0,025 g/l
28、 Cr Transfer 25,0 ml of the chromium stock solution (4.7) into a 500 ml one-mark volumetric flask. Dilute to the mark with water and mix well. Prepare this solution immediately prior to use. 1 ml of this solution contain 0,025 mg of Cr. 4.9 Copper base solution, 20 g/l Cu Weigh 20,0 g of chromium-fr
29、ee copper (Cu 99,90 %, Cr 0,001 %) and transfer into a 1 000 ml beaker. Add, in small portions, 400 ml of nitric acid solution (4.5). Cover the beaker. If necessary, heat gently to help dissolution. After cooling, add cautiously 200 ml of the sulphuric acid (4.2); heat to the evolution of copious wh
30、ite fumes and continue for 5 min. Cool and add cautiously about 200 ml of water and heat to complete the dissolution. Cool to room temperature, transfer the solution quantitatively into a 1 000 ml one-mark volumetric flask, dilute to the mark with water and mix well. 5 Apparatus 5.1 Ordinary laborat
31、ory apparatus. 5.2 Atomic absorption spectrometer, fitted with an air-acetylene or a nitrous-oxide acetylene burner. 5.3 Chromium hollow-cathode lamp. 6 Sampling Sampling shall be carried out in accordance with ISO 1811-1 or ISO 1811-2, as appropriate. Test samples shall be in the form of fine drill
32、ings, chips or millings with a maximum thickness of 0,5 mm. 7 Procedure 7.1 Preparation of the test portion solution 7.1.1 Test portion Weigh (1 0,001) g of the test sample. EN 14940-2:2006 (E) 6 7.1.2 Chromium mass fractions between 0,01 % and 0,20 % Transfer the test portion (7.1.1) into a 250 ml
33、beaker. Add 20 ml of the nitric acid solution (4.5) and 0,5 ml of hydrofluoric acid (4.6), cover and heat gently until the test portion is completely dissolved. Allow to cool and cautiously add 20 ml of the sulphuric acid (4.2). Heat on a sand bath at a temperature between 230 C and 240 C for at lea
34、st 4 h. Take care in the evaporation not to go under 20 ml. Allow to cool, add 20 ml to 30 ml of water and heat to dissolve the salts. Transfer the test solution into a 100 ml one-mark volumetric flask. Dilute to the mark with water and mix well. 7.1.3 Chromium mass fractions between 0,20 % and 2,0
35、% Transfer the test portion (7.1.1) into a 250 ml beaker. Add 20 ml of the nitric acid solution (4.5) and 0,5 ml of hydrofluoric acid (4.6), cover and heat gently until the test portion is completely dissolved. Allow to cool and cautiously add 20 ml of the sulphuric acid (4.2). Heat on a sand bath a
36、t a temperature between 230 C and 240 C for at least 4 h. Take care in the evaporation not to go under 20 ml. Allow to cool, add 20 ml to 30 ml of water and heat to dissolve the salts. Transfer the test solution into a 100 ml one-mark volumetric flask, dilute to the mark with water and mix well. Tra
37、nsfer 10,0 ml of this solution into another 100 ml one-mark volumetric flask. Add 45 ml of the copper base solution (4.9). Dilute to the mark with water and mix well. 7.2 Blank test Carry out a blank test simultaneously with the determination, following the same procedure and using the same quantiti
38、es of all reagents as used for the determination, but omitting the test portion. 7.3 Check test Make a preliminary check of the apparatus by preparing a solution of a standard material or a synthetic sample containing a known amount of chromium and of composition similar to the material to be analys
39、ed. Carry out the procedure specified in 7.5. 7.4 Establishment of the calibration curve 7.4.1 Preparation of the calibration solutions 7.4.1.1 General In all cases, copper, chloride and nitrate concentrations and acidity in the calibration solutions shall be similar to those of the test portion sol
40、utions. The presence of copper in the standard calibration solutions compensates for chemical interaction effects of copper in the test portion solution. Normally no similar additions are required to compensate for the effects of alloying elements. If any alloying element is present in the material
41、to be analysed in mass fraction 10 % an appropriate mass of this element shall be added to the calibration solutions. The chromium concentration of the calibration solutions shall be adjusted to suit the sensitivity of the spectrometer used, so that the curve of absorbance as a function of concentra
42、tion is a straight line. 7.4.1.2 Chromium mass fractions between 0,01 % and 2,0 % Introduce into each of a series of seven 100 ml one-mark volumetric flasks the volumes of chromium stock solu-tions (4.7) or chromium standard solutions (4.8) shown in Table 1. Into each flask add 50 ml of the copper b
43、ase solution (4.9). Dilute to the mark with water and mix well. EN 14940-2:2006 (E) 7 Table 1 Calibration for chromium mass fractions between 0,010 % and 2,0 % Chromium stock Corresponding Corresponding chromium mass or standard solution volume Corresponding chromium fraction of chromium concentrati
44、on (4.8) (4.7) mass after final dilution 1 g 0,1 g ml ml mg mg/ml % % 0a 0 0 0 0 4 0,10 0,001 0 0,010 8 0,20 0,002 0 0,020 0,20 20 0,50 0,005 0 0,050 0,50 2 1,0 0,010 0,10 1,0 3 1,50 0,015 0,150 1,50 4 2,0 0,020 0,20 2,0 aBlank test on reagents for calibration curve. 7.4.2 Adjustment of the atomic a
45、bsorption spectrometer Fit the chromium hollow-cathode lamp (5.3) into the atomic absorption spectrometer (5.2), switch on the current and allow to stabilize. Following the manufacturers instructions, fit the correct burner, light the flame and allow the burner temperature to stabilize. Taking caref
46、ul note of the manufacturers instructions regarding the minimum flow rate of acetylene, aspirate the calibration solution of highest concentration of analyte and adjust the burner configu-ration and gas flows to obtain maximum absorbance. 7.4.3 Spectrometric measurement of the calibration solutions
47、Aspirate the series of calibration solutions (7.4.1.2 depending on the expected chromium content) in succession into the flame and measure the absorbance for each. Take care to keep the aspiration rate constant throughout the preparation of the calibration curve. Spray water through the burner after
48、 each measurement, see note. NOTE For certain types of apparatus, instead of water it is preferable to use a solution containing the attack reagents, in the same concentrations as in the test portion solutions. 7.4.4 Establishment of the calibration curve Establish the calibration curve using measur
49、ed absorbances and corresponding analyte amounts. Use appropriate spectrometer software or off-line computer for regression calculations or prepare a graphical representation. 7.5 Determination 7.5.1 General The analyses shall be carried out independently, in duplicate. 7.5.2 Preliminary spectrometric measurement Carry out a preliminary measurement on the test portion solution (7.1.2 or 7.1.3) following the procedure specified in 7.4.2 and 7.4.3 at the same time as the spectrometric measurements are carried out on the calibrat
