SIST EN 14242:2004
(Main)Aluminium and aluminium alloys - Chemical analysis - Inductively coupled plasma optical emission spectral analysis
Aluminium and aluminium alloys - Chemical analysis - Inductively coupled plasma optical emission spectral analysis
This European Standard describes detailed steps for dissolution and preparation of calibration solutions. The pre-ferred use is for certification and referee analysis. All instrumentation, including software used in the testing labo-ratories, are different an subject to change. Therefore, general criteria for calibration and measurement are speci-fied.
This method has to be used with primary reference materials whose mass of substance have a significant smaller uncertainty as required of the repeatability of the testing procedure.
Aluminium und Aluminiumlegierungen - Chemische Analyse - Optische Emissionspektralanalyse mit induktiv gekoppelter Plasmaanregung
Dieser Europäische Norm-Entwurf legt die optische Emissionsspektralanalyse mit induktiv gekoppelter Plasmaanregung (ICP-OES) von Aluminium und Aluminiumlegierungen fest. Diese Methode ist für die Bestimmung von Silicium, Eisen, Kupfer, Mangan, Magnesium, Chrom, Nickel, Zink, Titan, Antimon, Beryllium, Bismut, Cadmium, Calcium, Cobalt, Gallium, Blei, Lithium, Natrium, Strontium, Zinn, Vanadium und Zirconium in Aluminium und Aluminiumlegierungen anwendbar.
Aluminium et alliages d'aluminium - Analyse chimique - Analyse par spectrométrie d'émission optique en plasma induit
Le présent document spécifie l'analyse par spectrométrie d'émission optique avec source en plasma induit (SEP SEO) de l'aluminium et des alliages d'aluminium. Cette méthode est applicable au dosage du silicium, fer, cuivre, manganese, magnésium, chrome, nickel, zinc, titane, antimoine, béryllium, bismuth, cadmium, calcium, cobalt, gallium, plomb, lithium, sodium, strontium, étain, vanadium et zirconium dans l'aluminium et les alliages d'aluminium.
NOTE Les consignes de sécurité nationales doivent etre observées.
Aluminij in aluminijeve zlitine – Kemična analiza – Analiza s spektrometrijo optične emisije z induktivno sklopljeno plazmo
General Information
Relations
Standards Content (Sample)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.HNWURPHWULMRAluminium und Aluminiumlegierungen - Chemische Analyse - Optische Emissionspektralanalyse mit induktiv gekoppelter PlasmaanregungAluminium et alliages d'aluminium - Analyse chimique - Analyse par spectrométrie d'émission optique en plasma induitAluminium and aluminium alloys - Chemical analysis - Inductively coupled plasma optical emission spectral analysis77.120.10Aluminij in aluminijeve zlitineAluminium and aluminium alloys77.040.30Kemijska analiza kovinChemical analysis of metalsICS:Ta slovenski standard je istoveten z:EN 14242:2004SIST EN 14242:2004en01-november-2004SIST EN 14242:2004SLOVENSKI
STANDARD
SIST EN 14242:2004
EUROPEAN STANDARDNORME EUROPÉENNEEUROPÄISCHE NORMEN 14242September 2004ICS 77.040.30; 77.120.10 English versionAluminium and aluminium alloys - Chemical analysis -Inductively coupled plasma optical emission spectral analysisAluminium et alliages d'aluminium - Analyse chimique -Analyse par spectrométrie d'émission optique en plasmainduitAluminium und Aluminiumlegierungen - ChemischeAnalyse - Optische Emissionspektralanalyse mit induktivgekoppelter PlasmaanregungThis European Standard was approved by CEN on 1 July 2004.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-to-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 the 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, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia,Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMITÉ EUROPÉEN DE NORMALISATIONEUROPÄISCHES KOMITEE FÜR NORMUNGManagement Centre: rue de Stassart, 36
B-1050 Brussels© 2004 CENAll rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 14242:2004: ESIST EN 14242:2004
EN 14242:2004 (E) 2 Contents page Foreword.3 Introduction.4 1 Scope.5 2 Normative references.5 3 Terms and definitions.5 4 Principle.5 5 Reagents.6 6 Equipment.7 7 Sampling and samples.8 8 Procedure.9 9 Correction of short-term fluctuations and drift.12 10 Investigation of interferences.12 11 Expression of the results.13 12 Test report.13 Annex A (informative)
Analytical lines.15 Annex B (informative)
Preparation of stock solutions.17 Bibliography.21
SIST EN 14242:2004
EN 14242:2004 (E) 3 Foreword This document (EN 14242:2004) has been prepared by Technical Committee CEN/TC 132 "Aluminium and alumin-ium alloys", the secretariat of which is held by AFNOR. 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 March 2005, and conflicting national standards shall be withdrawn at the latest by March 2005. Within its programme of work, Technical Committee CEN/TC 132 requested CEN/TC 132/WG 17 "Chemical
analysis" to prepare the following standard: EN 14242, Aluminium and aluminium alloys — Chemical analysis — Inductively coupled plasma optical emission spectral analysis. This document includes a Bibliography. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following coun-tries are bound to implement this European Standard: Austria, Belgium, Cyprus, Czech Republic, Denmark, Esto-nia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. SIST EN 14242:2004
EN 14242:2004 (E) 4 Introduction This document describes detailed steps for dissolution and preparation of calibration solutions. The preferred use is for certification and referee analysis. All instrumentation, including software used in the testing laboratories, are different and subject to change. Therefore, general criteria for calibration and measurement are specified. This method has to be used with primary reference materials whose mass of substance have a significant smaller uncertainty as required of the repeatability of the testing procedure. SIST EN 14242:2004
EN 14242:2004 (E) 5 1 Scope This document specifies the inductively coupled plasma optical emission spectral analysis
(ICP-OES) of aluminium and aluminium alloys. This method is applicable to the determination of silicon, iron, copper, manganese, magnesium, chromium, nickel, zinc, titanium, gallium, vanadium, beryllium, bismuth, calcium, cadmium, cobalt, lithium, sodium, lead, antimony, tin, strontium, and zirconium in aluminium and aluminium alloys. NOTE The national safety instructions should be taken into consideration. 2 Normative 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. prEN 12258-2:2001, Aluminium and aluminium alloys — Terms and definitions — Part 2: Chemical analysis. prEN 14361, Aluminium and aluminium alloys — Chemical analysis — Sampling from metal melts. EN ISO 3696, Water for analytical laboratory use — Specification and test methods (ISO 3696:1987). EN ISO/IEC 17025, General requirements for the competence of testing and calibration laboratories (ISO/IEC 17025:1999). ISO 3534-1, Statistics — Vocabulary and symbols — Part 1: Probability and general statistical terms. 3 Terms and definitions For the purposes of this document, the terms and definitions given in prEN 12258-2:2001 apply. 4 Principle A test portion is dissolved with: sodium hydroxide solution and acidification with a mixture of nitric acid and hydrochloric acid; or nitric acid and hydrofluoric acid; or a mixture of hydrochloric acid and nitric acid; or hydrochloric acid and hydrogen peroxide according to the alloy type and the element contents to be determined. This solution is nebulized and excited in an inductively coupled plasma connected with an optical emission spectrometer. The emission signals on selected analytical lines (see Annex A) are compared with those of calibration solutions. The ranges of application and the accuracy of the method or any alternative steps shall be validated by the labora-tory. Approximate ranges of application are given in Annex A. SIST EN 14242:2004
EN 14242:2004 (E) 6 5 Reagents 5.1 General All volumetric measurements shall be made at the temperature specified on the pipettes and volumetric flasks. Each mixture shall be thoroughly mixed. For the analysis, reagents of recognized analytical grade and deionized water, shall be used in accordance with
EN ISO 3696. 5.2 Sodium hydroxide solution (10 M) Dissolve 400,0 g sodium hydroxide NaOH in a plastic beaker with a lid. Transfer the solution to a 1 000 ml volumet-ric plastic flask and make up to volume with water. 5.3 Hydrogen peroxide, 30 % (mass fraction) solution 5.4 Nitric acid (ρ = 1,4 g/ml, 65 % mass fraction) 5.5 Nitric acid (1 + 1) Carefully add 500 ml nitric acid (5.4) to 400 ml water, allow to cool, and make up the volume to 1 000 ml with
water. 5.6 Nitric acid (4 M) Carefully add 27,7 ml nitric acid (5.4) to 50 ml water, allow to cool, and make up the volume to 100 ml with water. 5.7 Hydrochloric acid (ρ = 1,18 g/ml, 37 % mass fraction) 5.8 Hydrochloric acid (1 + 1) Carefully add 500 ml hydrochloric acid (5.7) to 400 ml water, allow to cool, and make up the volume to 1 000 ml with water. 5.9 Sodium nitrite 5.10 High-purity aluminium Aluminium, purity equal or better than 99,999 % mass fraction; the content of the elements to be determined shall not be higher than 10 % of the detection limits of this method or of the element content to be determined. 5.11 Hydrofluoric acid, (ρ = 1,14 g/ml, 40 % mass fraction) 5.12 Stock solutions The concentrations of the stock solutions shall be traceable to international standard units mass and amount of substances i.e. kilogram (kg) and mol (mol) according to EN ISO/IEC 17025. Examples of preparation of stock so-lutions are described in B.3. Stock solutions containing sulphate ions shall not be used if the determination of an element is required which forms insoluble compounds with sulphate. Stock solutions shall not to be used when the time of stability is expired. SIST EN 14242:2004
EN 14242:2004 (E) 7 5.13 Standard solutions Prepare standard solutions from the stock solutions by dilution steps not more than 1 : 5 using calibrated pipettes not smaller than 10 ml and calibrated volumetric flasks not smaller than 100 ml. Standard solutions and calibration solutions with element contents equal or less than 50 mg/l can be unstable and shall be prepared just before use. NOTE Calibration solutions can be made directly from stock solutions by means of weight measurement (see 8.4). 5.14 Reference element solutions 5.14.1 Reference element solution lanthanum, 1 g/l Transfer 1,173 g lanthanum oxide La2O3, purity equal or better than 99,99 % mass fraction, previously dried at 150 °C to constant mass, to a 400 ml beaker with a lid. Add 40 ml hydrochloric acid solution (5.8), transfer the solu-tion into a 1 000 ml volumetric flask and make up to volume with water. 5.14.2 Reference element solution, lanthanum, 200 mg/l Transfer 20,00 ml of reference element solution, lanthanum (5.14.1) into a 100 ml volumetric flask, add 1 ml hydro-chloric acid solution (5.8) and make up to volume with water. 5.14.3 Reference element solution, scandium, 0,1 g/l Transfer 100,0 mg scandium purity equal or better than 99,99 % mass fraction into a 400 ml beaker with a lid. Add 20 ml hydrochloric acid solution (5.8). Heat gently, if necessary, until the dissolution is complete, allow to cool, and transfer the solution into a 1 000 ml volumetric flask and make up to volume with water. NOTE Scandium solutions can be unstable. 5.14.4 Reference element solution, scandium, 20 mg/l Transfer 20,00 ml of reference element solution scandium (5.14.3) into a 100 ml volumetric flask, add 1 ml hydrochloric acid solution (5.8) and make up to volume with water. 5.14.5 Reference element solution, molybdenum, 1 g/l Transfer 1,84 g ammonium molybdate (NH4)6Mo7O24 × 4 H2O into a 1 000 ml volumetric flask and make up to volume with water. 5.14.6 Reference element solution, molybdenum, 200 mg/l Transfer 20,00 ml of reference element solution molybdenum (5.14.5) into a 100 ml volumetric flask, add 1 ml hydrochloric acid solution (5.8) and make up to volume with water. 6 Equipment 6.1 Optical emission spectrometer with inductively coupled argon plasma excitation and polychromator or monochromator (for analytical lines, see Annex A), for solutions containing hydrofluoric acid. The spectrometer shall be equipped with a fluoride-resistant nebulizer. NOTE The nebulizer should be selected carefully. Many of the available fluoride-resistant nebulizers are not as stable as standard nebulizers. SIST EN 14242:2004
EN 14242:2004 (E) 8 6.2 PTFE-beakers with lid, 400 ml 6.3 Platinum crucibles with a lid, 100 ml to 120 ml 6.4 Plastic measuring pipettes, 2,0 ml, 6,0 ml and 10,0 ml NOTE The plastic equipment should be selected carefully to avoid losses and contaminations. 6.5 Plastic bottle with small neck and cap, approximately 100 ml NOTE The plastic equipment should be selected carefully to avoid losses and contaminations. 6.6 Glass beakers with lid, 250 ml 6.7 Volumetric flasks, 100 ml and 500 ml 7 Sampling and samples 7.1 General Sampling from aluminium melts shall be carried out in accordance with prEN 14361. The analytical result shall indicate the average chemical composition of a test sample, a laboratory sample or an inspection lot. For an inspection lot or a laboratory sample the minimum quantity of laboratory samples or test samples, respectively shall be investigated by preliminary tests, for the determination of the average chemical composition of the inspection lot with the required accuracy. NOTE The aim is to determine the uncertainty contribution from the inconsistency of the chemical composition of the sam-ple and to determine the number of samples necessary to meet the required accuracy for the result with test portions of 0,5 g. 7.2 Laboratory sample A sufficient number of samples shall be taken to indicate the chemical composition of the inspection lot within the required uncertainty range. Usually, the analytical result refers to the average content of one or more laboratory samples supplied. If required, uncertainties that result from differences between the test samples and the average composition of one or more laboratory samples or an inspection lot outside the laboratory shall also be taken into account. 7.3 Test sample Make chips by milling or drilling of each laboratory sample. If the chemical composition of the laboratory sample is thought to be not uniform, e.g. in case of unwrought products, the preparation of the test sample shall follow a documented procedure to ensure the required representativity. If necessary, e.g. for the determination of low contents of alkaline or alkaline earth elements, clean with a suitable procedure (solution, temperature and time). The cleaning procedure shall be adapted to the alloy, analytes and the content to be determined. Make sure that the test sample is sufficient homogeneous for the quantity of the test portion. If not, take as many test portions as necessary to obtain an average test result within the required uncertainty range. SIST EN 14242:2004
EN 14242:2004 (E) 9 8 Procedure 8.1 Test portion 8.1.1 General Weigh, to the nearest 0,001 g, about 0,5 g of the test sample. 8.1.2 Dissolution procedure I with sodium hydroxide solution 8.1.2.1 General This procedure is applicable for the determination of silicon, iron, copper, manganese, magnesium, chromium, nickel, zinc, titanium, vanadium, beryllium, bismuth, cadmium, cobalt, lead, antimony, tin, strontium and zirconium in aluminium and aluminium alloys. NOTE Iron constituents can cause problems with dissolution. Under that dissolution condition, bismuth losses can occur. 8.1.2.2 Transfer the test portion (8.1) into a 400 ml PTFE-beaker with a lid (6.2) or a platinum crucible with lid (6.3). 8.1.2.3 Cover the test portion with water. Add 6,0 ml sodium hydroxide solution (5.2) using the plastic pipette (6.4). After the dissolution reaction ceases, add 1 ml hydrogen peroxide (5.3). Heat gently until the dissolution is complete. 8.1.2.4 If the silicon content of the test sample is more than 0,5 % mass fraction carefully evaporate to a syr-upy consistency. Allow to cool a little, carefully add 30 ml water and heat gently until the dissolution is complete. If the platinum crucible (6.3) has been used, transfer the solution quantitatively into a 400 ml PTFE-beaker, contain-ing 25,0 ml nitric acid (5.5) and 10,0 ml hydrochloric acid (5.8). 8.1.2.5 Make up to volume of about 100 ml with water and add 25,0 ml nitric acid solution (5.5) and 25,0 ml hydrochloric acid (5.8) while stirring. Heat the content of the beaker immediately while frequently and carefully shaking to complete the dissolution. In case of precipitation of manganese (IV)-oxyhydrate (at higher contents of manganese), dissolve with a spatula tip of sodium nitrite (5.9). Allow to cool and transfer the clear solution into a 500 ml volumetric flask. 8.1.2.6 If the platinum crucible (6.3) has been used, add into the empty crucible some drops of nitric acid (5.6) and a spatula tip of sodium nitrite (5.9), cover the crucible and heat. Rinse lid and walls with water. Let the solution cool. Transfer this solution quantitatively into the 500 ml flask (8.1.2.5). 8.1.2.7 If necessary for the precision required (see clause 9), add about 10 g to the nearest 0,01 g or 10,00 ml of one of the reference element solution (5.14.1, 5.14.3 or 5.14.5). 8.1.2.8 Make up to volume with water and mix. Continue with 8.2. 8.1.3 Dissolution procedure II with nitric acid and hydrofluoric acid 8.1.3.1 General This procedure is applicable for the determination of iron, copper, manganese, magnesium, chromium, nickel, zinc, titanium, gallium, vanadium, beryllium, bismuth, calcium, cadmium, cobalt, lithium, sodium, lead, antimony, tin, strontium and zirconium in aluminium and aluminium alloys. 8.1.3.2 Transfer the test portion (8.1) into a previously weighed 100 ml plastic bottle. 8.1.3.3 Add 10,0 ml nitric acid (5.5) and 2,0 ml hydrofluoric acid (5.11) using the plastic pipette (6.4). 8.1.3.4 Cover the bottle with the cap. Do not screw the cap. SIST EN 14242:2004
EN 14242:2004 (E) 10 8.1.3.5 Heat in a water bath or thermoblock (max. 70 °C) to complete the dissolution. 8.1.3.6 If necessary for the precision required (see clause 9), add about 2 g to the nearest 0,002 g of one of the reference element solutions (5.14.5) or 10,00 ml from one of the reference element solution (5.14.6). Do not add lanthanium or scandium reference element solutions to avoid fluoride precipitation. 8.1.3.7 Make up to 100,0 g with water and mix. Continue with 8.2. NOTE In case of a magnesium content higher than 1 % mass fraction insoluble magnesium fluoride can precipitate.
Select another dissolution procedure. 8.1.4 Dissolution procedure III with a mixture of hydrochloric acid and nitric acid 8.1.4.1 General This procedure is applicable for the determination of iron, copper, manganese, magnesium, chromium, nickel, zinc, titanium, gallium, vanadium, beryllium, bismuth, calcium, cadmium, cobalt, lithium, sodium, lead, antimony, tin, strontium and zirconium in aluminium and aluminium alloys with silicon contents less than 0,3 % mass fraction. 8.1.4.2 Transfer the test portion (8.1) into the 250 ml glass beaker with lid (6.6). 8.1.4.3 Add 10,0 ml acid mixture [3 parts hydrochloric acid (5.7) and 1 part nitric acid (5.4)]. Warm gently to complete the dissolution. 8.1.4.4 Transfer the solution quantitatively into the 100 ml volumetric flask (6.7). 8.1.4.5 If necessary for the precision required (see clause 9), add about 2 g to the nearest 0,002 g of one of the reference element solution (5.14.1, 5.14.3 or 5.14.5) or 10,00 ml from one of the reference element solution (5.14.2, 5.14.4 or 5.14.6). 8.1.4.6 Make up to volume with water and mix. Continue with 8.2. 8.1.5 Dissolution procedure IV with hydrochloric acid 8.1.5.1 General Applicable for the determination of iron, copper, manganese, magnesium, chromium, nickel, zinc, titanium, gallium, vanadium, beryllium, calcium, cadmium, cobalt, lithium, sodium, lead, tin, strontium, and zirconium in aluminium and aluminium alloys with silicon contents less than 0,3 % mass fraction. Applicable for the determination of iron, copper, manganese, magnesium, chromium, nickel, zinc, titanium, gallium, vanadium, beryllium, calcium, cobalt, lithium, sodium, tin, strontium and zirconium in aluminium and aluminium alloys with silicon contents more than 0,3 % mass fraction including the decomposition of undissolved matter (8.1.5.4). 8.1.5.2 Transfer the test portion (8.1) into the 250 ml glass beaker with lid (6.6). 8.1.5.3 Add 10 ml hydrochloric acid (5.8). Warm gently, if necessary. When the reaction ceases, add 1 ml of the hydrogen peroxide solution (5.3) and warm gently to complete the dissolution. 8.1.5.4 If undissolved matter remains, indicating the presence of more than 0,3 % mass fraction of silicon, filter the solution through an ashless filter paper, wash, transfer the filter paper and undissolved matter into a platinum crucible (6.3) and char, taking care that it does not inflame. Then calcine at 850 °C about 15 min. After cooling add 3 ml hydrofluoric acid (5.11) and dropwise, about 1 ml nitric acid (5.4). Evaporate near to dryness and allow to cool. Bring the residue into solution with 3 ml hydrochloric acid (5.8), and heat gently, if necessary, filter, if necessary, and add this filtrate quantitatively to the previous filtrate. NOTE This step can increase the blanks, especially for calcium and sodium 8.1.5.5 Transfer the solution quantitatively into a 100 ml volumetric flask. SIST EN 14242:2004
EN 14242:2004 (E) 11 8.1.5.6 If necessary for the precision required (see Clause 9), add about 2 g to the nearest 0,002 g of one of the reference element solution (5.14.1, 5.14.3 or 5.14.5) or 10,00 ml from one of the reference element solution (5.14.2, 5.14.4 or 5.14.6). 8.1.5.7 Make up to volume with water and mix. Continue with 8.2. 8.2 Measurement 8.2.1 Dilute the test solution (8.1.2.8, 8.1.3.7, 8.1.4.6 or 8.1.5.7), if necessary (see range in the Annex A). 8.2.2 Emission spectrometry of the test solution, the calibration solutions, blank solution and the drift correction solution using optimal conditions according to the proposals of the manufacturer of the spectrometer and the results obtained by pre-tests (see Clauses 9 and 10). Optimize the observation height, the pre-flushing time, the integration time, the generator efficiency and the carrier gas flow. The relative standard deviation s
according to ISO 3534-1 of the signal intensities shall be below 0,5 % for mass fractions higher than 1 % in the test portion. 8.3 Blank test At the same time and following the same procedure (8.1.2.2 to 8.1.2.8, 8.1.3.2 to 8.1.3.7, 8.1.4.2 to 8.1.4.6 or 8.1.5.2 to 8.1.5.7 respectively) carry out a blank test using all reagents and the high purity aluminium (5.10). 8.4 Calibration solutions and drift correction solution 8.4.1 Dissolution procedure I: Weigh, to the nearest 0,001 g about 0,5 g of the high purity aluminium (5.10) into a series of seven 400 ml PTFE beakers with lids (6.5) and follow the same procedure (8.1.2.3 to 8.1.2.7). Continue with 8.4.2. Dissolution procedure II: Weigh, to the nearest 0,001 g about 0,5 g of the high purity aluminium (5.10) into a series of seven previously weighed 100 ml plastic bottles (6.2) and follow the same procedure (8.1.3.3 to 8.1.3.6). Continue with 8.4.2. Dissolution procedure III: Weigh, to the nearest 0,001 g about 0,5 g of the high purity aluminium (5.10) into a series of 250 ml glass beakers (6.6) and follow the same procedure (8.1.4.3 to 8.1.4.5). Continue with 8.4.2. Dissolution procedure IV: Weigh, to the nearest 0,001 g about 0,5 g of the high purity aluminium (5.10) into a series of 250 ml glass beakers (6.6) and follow the same procedure (8.1.5.3 to 8.1.5.6). Continue with 8.4.2. For all dissolution procedures the mass of 0,5 g of the high purity aluminium (5.10) has to be reduced by the sum of element mass which are added under 8.4.2, if this sum is more than 2 % of the total mass. 8.4.2 Measure and transfer into the beakers or plastic bottles (8.4.1) alternate weights of the stock solutions (5.12) or volumes of the standard solutions (5.13) so that the element contents to be determined can be measured reliably. The solution with the highest analyte concentration shall be used as drift correction solution. The aluminium and the acid concentration of the calibration solutions shall correspond to the concentrations of the test solution. The calibration solutions, however, shall not correspond to a dilution series (see also Clause 9). The number of calibration solutions depends on the required precision. A minimum of five calibration solutions is required. The precision as well as the trueness of the result can be checked by bracketing with calibration solutions made from stock solutions as described in Annex B. 8.4.3 Make up to volume with water. Continue with 8.2. SIST EN 14242:2004
EN 14242:2004 (E) 12 9 Correction of short-term fluctuations and drift 9.1 General The precision and comparability of measured values can be influenced by short-term fluctuations, drift and matrix effects in solutions. Sometimes, it is difficult to separate the causes of these influences from one another. In any case, all three effects shall be taken into account appropriately. To reduce certain error inducing effects caused by the matrix, care shall be taken to ensure that the salt and, above all, acidic concentrations of the test, blank, cali-bration solutions are comparable and, as a consequence, a comparable atomising rate is achieved. 9.2 Short-term fluctuations Due to the different evaporation of solutions and different metal concentrations caused by the sample preparation and the preparation of the calibration solutions, the viscosity and surface tension of solutions can be different and, as a result, can influence the transport efficiency of the feeding to the atomiser. This, in turn, can affect the per-formance of a connected pump. Short-term fluctuations shall be corrected by adding a reference element (e.g. lan-thanium, molybdenum or scandium) to the test solution, blank solution and calibration solutions. Analyte and refer-ence element shall be measured simultaneously. Subsequent evaluation is made using the intensity ratio of the analyte to the reference element. 9.3 Drift Drift can be caused, for example, by changes in the excitation temperature or changes in the performance of the generator. To correct a signal drift test solutions and calibration solutions, at least the low point and the high point sample of the calibration series, shall be measured alternately throughout the entire analytical series so that the drift effect can be corrected. 10 Investigation of interferences 10.1 General The magnitude of the spectral and chemical interferences depend on the chemical composition of the sample and the resolution and the stability of the optical part of the spectrometer. The following tests shall be performed for each element which can interfere the analyte signal and shall be repeated periodically depending on the stability of the optical part of the spectrometer (10.2 to 10.5). 10.2 Prepare four matrix solutions according to 8.4.1. The mass of the high purity aluminium (5.10) shall be 0,5 g in all four solutions. 10.3 Add to three matrix solutions within the linear range of the calibration curve, alternate weights of the stock solution (5.12) or volume of the standard solutions (5.13) of the element. The concentration of the analyte in the matrix solutions used for those tests shall be below the detection limit of the method or shall be not more than 10 % mass fraction of the concentration of the analyte. Investigate blanks of interfering elements in the matrix solution and stock solutions using several analytical lines or an independent method (e.g. graphite furnace atomic absorption spectrometry). Interferences which are not cleared shall be given in the test report. 10.4 Measure according to 8.2. 10.5 Record the signal intensities of the solutions for the analytical lines and calculate the interference per equiva-lent mass content of the interfering element (correction factors). SIST EN 14242:2004
EN 14242:2004 (E) 13 11 Expression of the results 11.1 Correction Calculate, for each solution, the ratio of the measured intensity of the analyte and the intensity of the reference element recorded simultaneously, taking into account the reference element concentration. Calculate the
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.