EN 16206-2012 en Animal feeding stuffs - Determination of arsenic by hydride generation atomic absorption spectrometry (HGAAS) after microwave pressure digestion (digestion with 65.pdf

1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS EN 16206:2012Animal feeding stuffs Determination of arsenic byhydride generation atomicabsorption spectrometry(HGAAS) after microwavepressure digestion (digestionwith 65 % nit

2、ric acid and 30 %hydrogen peroxide)BS EN 16206:2012 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of EN 16206:2012.The UK participation in its preparation was entrusted to TechnicalCommittee AW/10, Animal feeding stuffs.A list of organizations represented on this co

3、mmittee can beobtained on request to its secretary.This publication does not purport to include all the necessaryprovisions of a contract. Users are responsible for its correctapplication. The British Standards Institution 2012. Published by BSI StandardsLimited 2012ISBN 978 0 580 66996 5ICS 65.120C

4、ompliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of theStandards Policy and Strategy Committee on 29 February 2012.Amendments issued since publicationDate Text affectedBS EN 16206:2012EUROPEAN STANDARD NORME EUROPE

5、NNE EUROPISCHE NORM EN 16206 February 2012 ICS 65.120 English Version Animal feeding stuffs - Determination of arsenic by hydride generation atomic absorption spectrometry (HGAAS) after microwave pressure digestion (digestion with 65 % nitric acid and 30 % hydrogen peroxide) Aliments pour animaux -

6、Dosage de larsenic par spectromtrie dabsorption atomique par gnration dhydrures (SAAGH) aprs digestion sous pression par micro-ondes (Extraction lacide nitrique 65 % et au peroxyde dhydrogne 30 %) Futtermittel - Bestimmung von Arsen mit Atomabsorptionsspektrometrie-Hydridtechnik (HD-AAS) nach Mikrow

7、ellen-Druckaufschluss (Aufschluss mit 65% Salpetersure und 30% Wasserstoffperoxid) This European Standard was approved by CEN on 30 December 2011. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of

8、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-CENELEC Management Centre or to any CEN member. This European Standard exists in three official versions (English, French, German).

9、 A version in any other language made by translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management Centre has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cy

10、prus, 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, Turkey and United Kingdom. EUROPEAN COMMITTEE FOR STANDARD

11、IZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels 2012 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 16206:2012: EBS EN 16206:2012EN 16206:2012 (E) 2 Conten

12、ts Page Foreword 31 Scope 42 Normative references 43 Principle 44 Reagents .55 Apparatus and equipment 66 Procedure .76.1 General 76.2 Preparation of the test solution 76.3 Measurement of the test solution 87 Calculation 98 Precision 108.1 Introduction . 108.2 General . 108.3 Repeatability 108.4 Rep

13、roducibility 109 Test report . 11Annex A (informative) Results of the inter-laboratory test 12Annex B (informative) Flowchart - Determination of arsenic by hydride generation atomic absorption spectrometry (HGAAS) after microwave pressure digestion (digestion with 65 % nitric acid and 30 % hydrogen

14、peroxide) 13Annex C (informative) Alternative digestion procedure with the same digestion efficiency to ensure complete mineralization of all organic and inorganic arsenic species for HGAAS measurement: dry ashing with magnesium oxide and magnesium nitrate as ashing reagents . 15Bibliography . 16BS

15、EN 16206:2012EN 16206:2012 (E) 3 Foreword This document (EN 16206:2012) has been prepared by Technical Committee CEN/TC 327 “Animal feeding stuffs”, 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

16、 text or by endorsement, at the latest by August 2012, and conflicting national standards shall be withdrawn at the latest by August 2012. Attention 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 respon

17、sible for identifying any or all such patent rights. This document has been prepared under a mandate given to CEN by the European Commission and the European Free Trade Association. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are

18、 bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spa

19、in, Sweden, Switzerland, Turkey and the United Kingdom. BS EN 16206:2012EN 16206:2012 (E) 4 1 Scope This European Standard specifies a method for the determination of total arsenic in animal feeding stuffs by hydride generation atomic absorption spectrometry (HGAAS) after microwave pressure digestio

20、n. The limit of quantification is 0,5 g/l of the test solution. Using a test portion of 0,5 g, a volume of the test solution of 25 ml and an aliquot of 5 ml for pre-reduction the limit of quantification is 0,125 mg/kg in the feed material. NOTE For feed materials containing organic arsenic species f

21、rom compounds of marine origin (i.e. arsenobetaine and tetramethylarsine oxide) a higher digestion temperature of the microwave system up to 300 C may be necessary in order to enable the hydridisation of these arsenic compounds and in order to determine all different kinds of arsenic species in the

22、corresponding feeding stuffs. Alternatively, the digestion procedure of Annex C can be used if the microwave system does not reach higher temperatures up to 300 C to ensure complete mineralization for HGAAS determination. 2 Normative references The following documents, in whole or in part, are norma

23、tively referenced in this document and are indispensable for its application. 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 Specification

24、 and test methods (ISO 3696) EN ISO 6497, Animal feeding stuffs Sampling (ISO 6497) prEN ISO 6498, Animal feeding stuffs Guidelines for sample preparation (ISO/DIS 6498) 3 Principle Arsenic is determined in the test solution by hydride generation atomic absorption spectrometry (HGAAS) after microwav

25、e pressure digestion and a pre-reduction step. The homogenised feeding stuff test sample is digested by nitric acid and hydrogen peroxide under pressure and high temperatures in a microwave-heated pressure digestion system. Arsenic ions of the test solution are reduced with a potassium iodide/ascorb

26、ic acid solution and hydrochloric acid to arsenic (III) and converted to arsenic hydride (AsH3) by sodium borohydride. Arsenic hydride is transferred by a gas stream into a heated measurement cell and decomposed. The absorption at the arsenic line at 193,7 nm corresponds to the amount of arsenic. Si

27、nce arsenic (III) and arsenic (V) show a different sensitivity with the hydride technique, it is necessary to reduce arsenic (V) to arsenic (III) in order to avoid incorrect measurements. Other digestion procedures with the same digestion efficiency are possible in order to completely mineralize all

28、 arsenic species like organic arsenic species from compounds of marine origin for HGAAS determination (see Annex C). NOTE 1 When using e.g. perchloric acid as alternative digestion procedure to ensure complete mineralisation of all organic and inorganic arsenic species for HGAAS determination you mu

29、st use NaI/L-ascorbic acid because KI results in precipitation of potassium perchlorate. NOTE 2 Alternatively, inductively-coupled-plasma mass-spectrometry (ICP-MS) for measuring can be used where an incomplete mineralization is not of importance. WARNING The use of this standard can involve hazardo

30、us 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 standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prio

31、r to use. BS EN 16206:2012EN 16206:2012 (E) 5 4 Reagents The concentration of the trace elements in the reagents and water used shall be low enough not to affect the results of the determination. A blank should be measured simultaneously with the test samples on each day of the analysis to control c

32、ontamination and carry over with arsenic in the reagents and apparatus used. Use water conforming to grade 2 of EN ISO 3696. NOTE High purity is essential to avoid potential contamination. Therefore, only use reagents available with high purity or perform a digestion by a sub-boiling distillation fo

33、r nitric acid (4.1). 4.1 Nitric acid, not less than 65 % (mass fraction), of approximately (HNO3) = 1,4 g/ml. 4.2 Hydrogen peroxide, not less than 30 % (mass fraction), of approximately (H2O2) 1,1 g/ml. 4.3 Hydrochloric acid, 30 % (mass fraction), of approximately (HCl) 1,15 g/ml. 4.4 Diluted hydroc

34、hloric acid, e.g. about 3 % (mass fraction), used as carrier solution in the flow injection procedure and for dilution of the arsenic stock solution to the 1 mg/l standard solution and furthermore to the calibration solutions. EXAMPLE Dilute approximately 90 ml of hydrochloric acid (4.3) to 1 l with

35、 water. 4.5 Sodium borohydride solution, e.g. c = 2 g/l. Dissolve 2 g of sodium hydroxide pellets in water, add 2 g of sodium borohydride and dilute to 1 000 ml with water into 1 000 ml flask (5.3). Prepare a fresh solution daily and, when necessary, filter before use. When the analysis procedure ta

36、kes longer, it is recommended to cool the sodium borohydride solution, i.e. with ice around the flask, during its use in the HGAAS measurement. NOTE 1 The concentration by mass of the sodium borohydride solution may vary with the system and the instructions of the relevant manufacturer shall therefo

37、re be observed. NOTE 2 Sodium borohydride, stable aq. solution, 4,4 mol/l in 14 mol/l NaOH is also commercially available. WARNING It is essential to observe the safety instructions for working with sodium borohydride. Sodium borohydride forms hydrogen with acids and this can result in an explosive

38、air/hydrogen mixture. A permanent extraction system shall be provided at the point where measurements are carried out. 4.6 Potassium iodide/ascorbic acid solution. Dissolve 2,5 g of potassium iodide and 2,5 g of L-ascorbic acid in water and dilute to 100 ml. Prepare a fresh solution on the day of th

39、e analysis. NOTE The concentrations of the potassium iodide and ascorbic acid may vary slightly with the system and the instructions of the relevant manufacturer shall therefore be observed. 4.7 Arsenic stock solution, c (As) = 1 000 mg/l. Stock solutions are commercially available. It is advisable

40、to use certified stock solutions. Otherwise dissolve 1,320 g of diarsenic trioxide (As2O3) in 25 ml of potassium hydroxide solution (c = 20 g/100 ml), neutralize with 20 % (mass fraction) sulfuric acid with phenolphthalein as indicator and dilute to 1 000 ml with 1 % (mass fraction) sulfuric acid. 4

41、.8 Arsenic standard solution, c (As) = 1 mg/l. Pipette, for example, 100 l of the stock solution (4.7) into a 100 ml flask (5.3) and fill up with hydrochloric acid (4.4) to reach a concentration of 1 mg/l. BS EN 16206:2012EN 16206:2012 (E) 6 NOTE The standard solution is stable for at least three mo

42、nths. 4.9 Arsenic calibration solutions. For the preparation of five calibration solutions the following procedure is recommended: Dilute 0 ml, 1,25 ml, 2,5 ml, 7,5 ml and 12,5 ml of the arsenic standard solution (4.8) with hydrochloric acid (4.4) into 50 ml flasks (5.3) and mix thoroughly. Then pip

43、ette 1 ml of each solution into 25 ml flasks (5.3), add 2,5 ml potassium iodide/ascorbic acid solution (4.6) and 2,5 ml of hydrochloric acid (4.3), mix thoroughly, and let the solutions stand at room temperature for 60 min. Finally make up to the mark with hydrochloric acid (4.4) and wait again 60 m

44、in at room temperature before the calibration solutions are measured (see Table 2). The concentrations of the calibration solutions are: 0 g/l, 1 g/l, 2 g/l, 6 g/l and 10 g/l (see Table 1). Table 1 Calibration solution concentrations (4.9) after pre-reduction Arsenic (As) Concentration of calibratio

45、n solution (4.9) after pipetting 1 ml from the 50 ml flasks (5.3) into 25 ml flasks (5.3) for pre-reduction g/l Aliquot of arsenic standard solution (4.8) transferred in 50 ml flasks (5.3) ml Calibration standard 1 0 0 Calibration standard 2 1 1,25 Calibration standard 3 2 2,50 Calibration standard

46、4 6 7,50 Calibration standard 5 10 12,5 Choose the concentrations of the calibration solutions so as not to exceed the linear range of the calibration function. It is recommended to use a minimum of five calibration solutions with different concentrations. The calibration solutions are measured from

47、 the lowest to the highest concentration. In general, the calibration curve should be linear. Using a non-linear calibration function is possible if it is well described. NOTE Prepare fresh calibration solutions (inclusive pre-reduction step) on the day of the analysis. 5 Apparatus and equipment To

48、minimise the contamination, all apparatus which come into direct contact with the sample and the solutions should be carefully pre-treated according to EN 13804. 5.1 Microwave-heated pressure digestion apparatus with inert reaction vessels, i.e. made of polytetrafluoroethylene (PTFE), perfluoroalkox

49、y (PFA), fluorinated ethylene propylene (FEP) or quartz, suitable for digestion temperatures of more than 200 C. NOTE 1 The microwave oven should be generally resistant to corrosion and the electronics should be especially protected against corrosion to ensure safe operation. The ventilation should transfer the acid vapours to an extractor hood or a fume cupboard. NOTE 2 The reaction vessels should have a safety valve designed for a pressure of 1 000 kPa. 5