1、December 2007DEUTSCHE NORM English price group 12No part of this standard may be reproduced without prior permission ofDIN Deutsches Institut fr Normung e. V., Berlin. Beuth Verlag GmbH, 10772 Berlin, Germany,has the exclusive right of sale for German Standards (DIN-Normen).ICS 65.120!$J“1399657www.
2、din.deDDIN EN 15550Animal feeding stuffs Determination of cadmium and lead by graphite furnace atomicabsorption spectrometry (GF-AAS) after pressure digestionEnglish version of DIN EN 15550:2007-12Futtermittel Bestimmung von Cadmium und Blei mittelsGraphitrohrofen-Atomabsorptionsspektrometrie (GF-AA
3、S) nach DruckaufschlussEnglische Fassung DIN EN 15550:2007-12www.beuth.deDocument comprises 18 pagesDIN EN 15550:2007-12 2 National foreword This standard has been prepared by Technical Committee CEN/TC 327 “Animal feeding stuffs Methods of sampling and analysis” (Secretariat: NEN, the Netherlands).
4、 The responsible German body involved in its preparation was the Normenausschuss Lebensmittel und landwirtschaftliche Produkte (Food and Agricultural Products Standards Committee), Technical Committee Futtermittel. The DIN Standard corresponding to the International Standard referred to in the EN is
5、 as follows: ISO 5725-1 DIN ISO 5725-1 National Annex NA (informative) Bibliography DIN ISO 5725-1, Accuracy (trueness and precision) of measurement methods and results Part 1: General principles and definitions EUROPEAN STANDARDNORME EUROPENNEEUROPISCHE NORMEN 15550October 2007ICS 65.120English Ver
6、sionAnimal feeding stuffs - Determination of cadmium and lead bygraphite furnace atomic absorption spectrometry (GF-AAS) afterpressure digestionAliments des animaux - Dtermination de la teneur encadmium et en plomb par spectromtrie dabsorptionatomique four graphite (GF-AAS) aprs digestion souspressi
7、onFuttermittel - Bestimmung von Cadmium und Blei mittelsGraphitrohrofen-Atomabsorptionsspektrometrie (GF-AAS)nach DruckaufschlussThis European Standard was approved by CEN on 26 August 2007.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for g
8、iving 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 CEN Management Centre or to any CEN member.This European Standard exists in three official ver
9、sions (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 CEN Management Centre has the same status as theofficial versions.CEN members are the national standards bodies of Austria, Belgium,
10、Bulgaria, Cyprus, Czech Republic, Denmark, 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.EUROPEAN COMMITTEE FOR STANDAR
11、DIZATIONCOMIT EUROPEN DE NORMALISATIONEUROPISCHES KOMITEE FR NORMUNGManagement Centre: rue de Stassart, 36 B-1050 Brussels 2007 CEN All rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 15550:2007: EEN 15550:2007 (E) 2 Contents Page Foreword3
12、1 Scope 4 2 Normative references 4 3 Terms and definitions .4 4 Principle5 5 Reagents.5 6 Apparatus .6 7 Sampling.6 8 Preparation of the test sample .7 9 Procedure .7 10 Calculation and expression of the result 9 11 Precision.10 12 Test report 11 Annex A (informative) Results of the interlaboratory
13、tests.12 Annex B (informative) Notes on the detection technique, interferences and quantification, pressure digestion.14 Bibliography 16 EN 15550:2007 (E) 3 Foreword This document (EN 15550:2007) has been prepared by Technical Committee CEN/TC 327 “Animal feeding stuffs - Methods of sampling and ana
14、lysis”, the secretariat of which is held by NEN. 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 April 2008, and conflicting national standards shall be withdrawn at the latest by April 2008. Atte
15、ntion is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and/or CENELEC shall not be held responsible for identifying any or all such patent rights. According to the CEN/CENELEC Internal Regulations, the national standards organizations of
16、 the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slov
17、akia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. EN 15550:2007 (E) 4 1 Scope This European Standard specifies a method for the determination of the elements cadmium and lead in animal feeding stuffs by graphite furnace atomic absorption spectrometry (GF-AAS) after pressure digestio
18、n. The method limit of quantification for each element is dependent on the sample matrix as well as the instrument. For cadmium a limit of quantification of 0,05 mg/kg should normally be obtained while for lead, a limit of quantification of 0,5 mg/kg should be obtained. 2 Normative references The fo
19、llowing 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. EN ISO 3696, Water for analytical laboratory use Specif
20、ication and test methods (ISO 3696:1987) ISO 6498, Animal feeding stuffs Preparation of test samples 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 limit of detection (LOD) smallest measured content from which it is possible to deduce the pr
21、esence of the analyte with reasonable statistical certainty NOTE The limit of detection is numerically equal to three times the standard deviation of the mean of blank determinations (n 10, where n = number of measures) performed under reproducibility conditions. 3.2 limit of quantification (LOQ) lo
22、west content of the analyte that can be measured with reasonable statistical certainty NOTE If both trueness and precision are constant over a concentration range around the limit of detection, then the limit of quantification is numerically equal to ten times the standard deviation of the mean of b
23、lank determinations (n 10, were n = number of measures) performed under reproducibility conditions. 3.3 feed additives substances that comply with the definition of feed additives given in the Regulation (EC) No 1831/2003 of the European Parliament and of the Council of 22 September 2003 on additive
24、s for use in animal nutrition 3.4 animal feeding stuffs substances that comply with the definition of animal feeding stuffs given in the Regulation (EC) No 178/2002 EN 15550:2007 (E) 5 4 Principle For the determination of the elements cadmium and lead, a test portion of the sample is digested under
25、pressure. The concentration of the elements is determined by graphite furnace atomic absorption spectrometry (GF-AAS) using external calibration. The method detection limit for each element is dependent on the sample matrix as well as the instrument, the type of atomizer and the use of chemical modi
26、fiers. A typical sample volume of 10 l to 20 l is used. WARNING Use of this European Standard can involve hazardous materials, operations and equipment. This standard does not purport to address all the safety problems associated with its use. It is the responsibility of the user of this European St
27、andard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use. 5 Reagents 5.1 General Use only reagents of recognized analytical grade, and water conforming to grade 2 of EN ISO 3696. 5.2 Nitric Acid, concentrated, not less than 65
28、 % (mass fraction), c(HNO3) = 14,4 mol/l, having a density of approximately (HNO3) = 1,42 g/ml. 5.3 Hydrogen peroxide, mass fraction not less than 30 %. 5.4 Element stock solutions Cd, Pb c = 1 000 mg/l The user should choose a suitable stock solution. Both single-element stock solutions and multi-e
29、lement stock solutions with adequate specifications stating the acid used and the preparation technique are commercially available. It is advisable to use certified stock solutions. Stock solutions should not be used after expiration dates. Element stock solutions with concentrations different from
30、1 000 mg/l may also be used. 5.5 Calibration solutions Prepare a range of standards including a blank calibration solution, which covers the linear range of the element to be determined by diluting the element stock solutions (5.4). Appropriate matrix matching of the calibration solutions shall be p
31、erformed (see Annex B), e.g. adjust the acid concentration of the standards to the acid concentration of the samples. Dilute to volume with water. 5.6 Matrix modifier (e.g. Palladium nitrate/magnesium nitrate modifier) Pd(NO3)2solution (Pd-nitrate solution) is commercially available (mass concentrat
32、ion 10 g/l). Dissolve 0,259 g of Mg(NO3)26H20 (Mg-nitrate solution) in 100 ml of water. Mix the Pd-nitrate solution with twice as much Mg-nitrate solution. 10 l of the mixed solution is equal to 15 g Pd and 10 g Mg(NO3)2. It is advisable to use this solution for not longer than one week. EN 15550:20
33、07 (E) 6 The combination of Pd and Mg(NO3) is regarded as a “universal” modifier that could be used for a lot of elements. Other matrix modifiers may be used as well, e.g. palladium nitrate modifier and ammonium dihydrogen phosphate modifier. 5.7 Purge and protective gas Argon, Ar purity not less th
34、an 99,99% by volume. 6 Apparatus Usual laboratory apparatus and, in particular, the following. 6.1 Laboratory grinder 6.1.1 Use laboratory grinders that are equipped so that samples cannot be contaminated. 6.1.2 Laboratory grinder capable of grinding to a particle size of less than or equal to 1 mm,
35、 e.g. a knife mill or equivalent. 6.1.3 Laboratory grinder capable of grinding to a particle size of less than or equal to 0,1 mm, e.g. a ball mill or equivalent. 6.1.4 Mortar with pestle, free of contamination. 6.2 Analytical balance, capable of weighing with an accuracy of 1 mg. 6.3 Pressure diges
36、tion apparatus, commercially available. The apparatus shall be tested for safety pressure vessels made of acid-resistant materials and having holders for the sample of acid-resistant material with a low level of contamination. Apparatus are available that uses a high-pressure incinerator with or wit
37、hout ambient autoclave pressure. Instead of polytetrafluoroethylene (PTFE) holders, it is better to use graduated quartz holders, perfluoro ethylene propylene (FEP) holders or perfluoro alkoxy (PFA) holders. Quartz is advisable to be used for decomposition temperatures above 230 C. 6.4 Graphite furn
38、ace atomic absorption spectrometer, with background correction, e.g. Zeeman, supplied with auto sampler, an appropriate gas (5.7) supply and hollow cathode lamps or EDL-lamps for lead and cadmium. NOTE It is necessary to place an exhaust venting system over the furnace to remove any smoke and vapour
39、s that might be harmful. 6.5 Graphite tubes, pyrolytically coated and preferably with platforms. 6.6 Freeze drying equipment, capable of freeze-drying liquid animal feeding stuffs. 7 Sampling Sampling is not part of the method specified in this International Standard. A recommended sampling method i
40、s given in EN ISO 6497. It is important that the laboratory receives a sample that is truly representative and has not been damaged or changed during transport or storage. EN 15550:2007 (E) 7 8 Preparation of the test sample 8.1 General Prepare the test sample in accordance with ISO 6498. Grinding m
41、ust be done in conditions such that the substance is not appreciably heated. Operation is to be repeated as many times as is necessary and it must be effected as quickly as possible in order to prevent any gain or loss of constituents (water). Whole ground product is placed in a flask made of e.g. p
42、olypropylene, which can be stoppered and stored in such way to prevent any change in composition. Before any weighing is carried out for the analysis, the whole test sample must be thoroughly mixed for reasons of homogeneity. 8.2 Animal feeding stuffs which can be ground as such Grind the laboratory
43、 sample (usually 500 g), using a grinder (6.1.2) or mortar (6.1.4), until a particle size of 1 mm or less has been reached. 8.3 Liquid animal feeding stuffs 8.3.1 General Liquid feeding stuffs shall be pre-dried according to the procedure described in 8.3.2 or freeze-dried according to the procedure
44、 described in 8.3.3. 8.3.2 Pre-drying Pre-dry the laboratory sample at 70 C 5 C during at least 16 h to reduce the moisture content. The mass of the sample before and after the pre-drying is to be determined using an analytical balance (6.2). Grind the pre-dried sample in accordance with 8.2. 8.3.3
45、Freeze-drying Freeze-dry the laboratory sample following the instructions of the freeze-drying equipment (6.6). The mass of the sample before and after the freeze-drying is to be determined using an analytical balance (6.2). Grind the freeze-dried sample in accordance with 8.2. 8.4 Mineral animal fe
46、eding stuffs Mineral compounds, except mineral products containing crystalline water, e.g. MgCl26H2O, shall be ground using a grinder (6.1.3) or mortar (6.1.4), until a particle size of 0,1 mm or less has been reached. Mineral products containing crystalline water should not be ground. 9 Procedure 9
47、.1 Digestion 9.1.1 General Use pressure digestion. Proceed in accordance with 9.1.2. EN 15550:2007 (E) 8 9.1.2 Pressure digestion 9.1.2.1 General Match the initial sample mass to the capacity of the digestion vessel, strictly observing the manufacturers instructions for safety reasons. Determine the
48、 necessary digestion temperature and digestion time (see EN 13805, see Annex B). 9.1.2.2 Example of microwave digestion When using 70 ml to 100 ml vessels, weigh about 0,5 g of the prepared test sample to the nearest 1 mg. Add 3 ml of nitric acid (5.2) and 0,5 ml of hydrogen peroxide (5.3), seal the
49、 digestion vessel and the pressure holders in the correct manner. Leave to pre-digest outside the microwave for about 30 min. Apply low microwave energy at the beginning of the digestion and slowly raise the energy to the maximum power, e.g. start with 100 W, raise up to 600 W within 5 min, hold for 5 min, raise to 1 000 W, hold for 10 min, cool down for minimum 20 min to 25 min. Treat a blank in the same way. Dilute the digestion solution accordingly and proceed in accordance with 9.2. 9.1.2.3 Example of a high pressure dige
