EN 14332-2004 en Foodstuffs - Determination of trace elements - Determination of arsenic in seafood by graphite furnace atomic absorption spectrometry (GFAAS) after microwave diges.pdf

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1、BRITISH STANDARD BS EN 14332:2004 Foodstuffs Determination of trace elements Determination of arsenic in seafood by graphite furnace atomic absorption spectrometry (GFAAS) after microwave digestion The European Standard EN 14332:2004 has the status of a British Standard ICS 67.120.30 BS EN 14332:200

2、4 This British Standard was published under the authority of the Standards Policy and Strategy Committee on 22 July 2004 BSI 22 July 2004 ISBN 0 580 44133 4 National foreword This British Standard is the official English language version of EN 14332:2004. The UK participation in its preparation was

3、entrusted to Technical Committee AW/-/3, Horizontal analysis, which has the responsibility to: A list of organizations represented on this committee can be obtained on request to its secretary. Cross-references The British Standards which implement international or European publications referred to

4、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 Catalogue or of British Standards Online. This publication does not purport to include all the necessary provisions of

5、 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 text; present to the responsible international/European committee any enquiries on the interpretation, or prop

6、osals for change, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. Summary of pages This document comprises a front cover, an inside front cover, the EN title page, pages 2 to 11 and a back cover. The BSI copyright notice disp

7、layed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. Date CommentsEUROPEANSTANDARD NORMEEUROPENNE EUROPISCHENORM EN14332 July2004 ICS67.120.30 Englishversion FoodstuffsDeterminationoftraceelementsDeterminationof arsenicinseafoodbygraphitefu

8、rnaceatomicabsorption spectrometry(GFAAS)aftermicrowavedigestion ProduitsalimentairesDosagedeslmentstrace Dterminationdelarsenicdanslesalimentsdorigine marineparspectromtriedabsorptionatomiquefour graphite(GFAAS)aprsdigestionparmicroondes LebensmittelBestimmungvonElementspuren BestimmungvonArseninMe

9、eresfrchtenmitGraphitofen Atomabsorptionsspektrometrie(GFAAS)nach Mikrowellenaufschluss ThisEuropeanStandardwasapprovedbyCENon30April2004. CENmembersareboundtocomplywiththeCEN/CENELECInternalRegulationswhichstipulatetheconditionsforgivingthisEurope an Standardthestatusofanationalstandardwithoutanyal

10、teration.Uptodatelistsandbibliographicalreferencesconcernings uchnational standardsmaybeobtainedonapplicationtotheCentralSecretariatortoanyCENmember. ThisEuropeanStandardexistsinthreeofficialversions(English,French,German).Aversioninanyotherlanguagemadebytra nslation undertheresponsibilityofaCENmemb

11、erintoitsownlanguageandnotifiedtotheCentralSecretariathasthesamestatusast heofficial versions. CENmembersarethenationalstandardsbodiesofAustria,Belgium,Cyprus,CzechRepublic,Denmark,Estonia,Finland,France, Germany,Greece,Hungary,Iceland,Ireland,Italy,Latvia,Lithuania,Luxembourg,Malta,Netherlands,Norw

12、ay,Poland,Portugal, Slovakia, Slovenia,Spain,Sweden,SwitzerlandandUnitedKingdom. EUROPEANCOMMITTEEFORSTANDARDIZATION COMITEUROPENDENORMALISATION EUROPISCHESKOMITEEFRNORMUNG ManagementCentre:ruedeStassart,36B1050Brussels 2004CEN Allrightsofexploitationinanyformandbyanymeansreserved worldwideforCENnat

13、ionalMembers. Ref.No.EN14332:2004:EEN 14332:2004 (E) 2 Contents Foreword3 1 Scope 4 2 Normative references 4 3 Principle4 4 Reagents.4 5 Apparatus and equipment 5 6 Procedure .6 7 Calculation8 8 Limit of quantification .8 9 Precision.8 10 Test report 9 Annex A (informative) Results of the interlabor

14、atory tests.10 Bibliography 11 EN 14332:2004 (E) 3 Foreword This document (EN 14332:2004) has been prepared by Technical Committee CEN/TC 275 “Food analysis - Horizontal methods”, the secretariat of which is held by DIN. This European Standard shall be given the status of a national standard, either

15、 by publication of an identical text or by endorsement, at the latest by January 2005, and conflicting national standards shall be withdrawn at the latest by January 2005. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to

16、implement this European Standard: 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 Kin

17、gdom. EN 14332:2004 (E) 4 1 Scope This document specifies a method for the determination of arsenic in seafood by graphite furnace atomic absorption spectrometry (GFAAS) after microwave digestion 1, 2. The collaborative study has included food having an arsenic content 2 mg/kg dry matter. Specific f

18、oodstuffs for which European Standards exist are excluded from the scope of this horizontal document. It is the task of the analyst to review if vertical documents exist. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated refer

19、ences, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 13804, Foodstuffs Determination of trace elements Performance criteria, general considerations and sample preparation. EN 13805, Foodstuffs Determinatio

20、n of trace elements Pressure digestion. 3 Principle The samples are digested in closed vessels in a microwave oven in a mixture of nitric acid and hydrogen peroxide. The resulting solution is diluted with water, and the arsenic contents are determined by GFAAS using matrix modifiers. WARNING The use

21、 of this document may involve hazardous materials, operations and equipment. This document does not purport to address all the safety problems associated with its use. It is the responsibility of the user of this document to establish appropriate safety and health practices and determine the applica

22、bility of regulatory limitations prior to use. 4 Reagents 4.1 General The concentration of arsenic in the reagents and water shall be low enough not to affect the results of the determination. EN 14332:2004 (E) 5 4.2 Nitric acid, w 65 % (mass fraction), having a density of approximately (HNO 3 ) = 1

23、,4 g/ml. In case of insufficient purity it is necessary to purify the acid in a distillation apparatus as described in EN 13805. 4.2.1 Diluted nitric acid solution 1, w = 6,5 % (mass fraction), to be prepared by mixing nitric acid (4.2) and water in a proportion minimum of 1 + 9 parts by volume. 4.2

24、.2 Diluted nitric acid solution 2, w = 0,65 % (mass fraction), to be prepared by mixing nitric acid (4.2) and water in a proportion minimum of 1 + 99 parts by volume. 4.3 Hydrogen peroxide, w (H 2 O 2 ) = 30 % (mass fraction) 4.4 Arsenic stock solution, with a mass concentration (As) = 1 000 mg/l. T

25、he use of a stock solution accompanied by a certificate is advisable. 4.5 Arsenic calibration solutions Dilute arsenic stock solution (4.4) with diluted nitric acid (4.2.2) to the required number of solutions, which cover the linear range of the calibration curve of arsenic. 4.6 Matrix modifiers 4.6

26、.1 General Instead of solutions 4.6.2 and 4.6.4, commercially available palladium nitrate and magnesium nitrate solutions may be used. 4.6.2 Palladium stock solution (Pd) = 10 mg/ml. Dissolve 2,16 g of palladium nitrate, Pd(NO 3 ) 2in approximately 10 ml of 6,5 % nitric acid (4.2.1) in a 100 ml volu

27、metric flask and dilute to volume with water. 4.6.3 Palladium solution (Pd) = 1,5 mg/ml Dilute 1,5 ml of palladium stock solution (4.6.2) to 10 ml in a volumetric flask with 0,65 % nitric acid (4.2.2). 4.6.4 Magnesium stock solution (Mg) = 10 mg/ml Dissolve 10,54 g magnesium nitrate, Mg(NO 3 ) 2 6H

28、2 O in approximately 10 ml of 6,5 % nitric acid (4.2.1) in a 100 ml volumetric flask and dilute to volume with water. 4.6.5 Magnesium solution (Mg) = 1 mg/ml Dilute 1 ml magnesium stock solution (4.6.4) to 10 ml in a volumetric flask with 0,65 % nitric acid (4.2.2). 4.6.6 Palladium nitrate/magnesium

29、 nitrate solution, to be prepared with appropriate volume of palladium solution (4.6.3) and magnesium solution (4.6.5) (1 + 1). 10 l of the solution gives 7,5 g Pd and 5,0 g Mg. 5 Apparatus and equipment 5.1 General All glassware and plastic ware shall be carefully cleaned and rinsed according to th

30、e procedure in EN 13804. 5.2 Microwvao ev,nef o rlatarobyro,esu chkcef deorled vire depower accordnit ot gh eprcorudeei n EN 14332:2004 (E) 6 EN 13804. 5.3 Atomic absorption spectrometer (AAS), with background correction, supplied with a graphite furnace consisting of a pyrolytically coated graphite

31、 tube with a pyrolytically coated platforms and autosampler. 5.4 Element specific lamp for arsenic 5.5 Argon, the purity not less than 99,998 % 6 Procedure 6.1 Pre-treatment Homogenise the sample in accordance with the recommendations in EN 13804. If necessary, dry the sample in a way that does not

32、affect the arsenic content, e.g. by freeze drying. 6.2 Sample preparation Use the test solution obtained by a suitable microwave oven digestion method e.g. EN 13805 for the determination of arsenic. 6.3 Determination 6.3.1 Spectrometer settings Before every determination, adjust the instrument as sp

33、ecified in the manufacturers operating manual. Then determine an optimum test schedule (if possible using a sample matrix) taking into account, in particular, of parameters such as temperatures and times for the different steps in the temperature program. Example of instrument parameters for arsenic

34、 may be a wavelength of 193,7 nm and slit 0,7 nm. :23341 NE4002 (E) 5 4.2 Nirtci acdi, w ( % 56 massf rca)noith ,avignd a esntiy ofa prpxomiletay (ONH 3 )1 = ,m/g 4lc nI .aseo f sniufficip tneurityi ti sn ecessary ot rupfiyt h eac di nid aistlitaliona praptasua ssed cr debi ni1 NE308 .5 1.2.4 uliDte

35、d nitrdica cis oultion ,1w = % 5,6 (mssaf rca)noit ot , ebprrapeb deym ixin gnirtcia c( di4.2)a n d retawi na prporooitnm iminumo f9 + 1 rapstb y vomule . 2.2.4 uliDted nitrdica cis oultion ,2w = 56,0( % msas frcati)not ,ob ep rerapdeb ym ixin gnirtcia c( di4.2)a n d retawi na prporooitnm iminumo f9

36、 + 1 9rap st by voulme . 4.3H y negord ixorep ,ed w (H 2 O 2 )3 = 0( % msas frca)noit 4.4 Arinescs ts kcooluti ,nowithm a assc ocnrtneait no (As)= 0 10m 0g .l/ Thu eso efs a tcoks onoitul accomeinapdb ya certficitai esa dvisabl .e 4.5 Arinesclac ibtaris nootuli sno liDusra etenics tcoks ooitulnd hti

37、w )4.4( iluetrtin dcia ct ot )2.2.4( dihuqer en deriumo rebf soitulsno ,whcic hovet rhe nilraer an egofc eht alirbatic nourvo efa rscine. 4.6M atrix domifi sre 1.6.4G ene lar snItdaeo fs oluitsno .6.4a 2n d.6.4c ,4ommrecillay avaiballep alldamuirtin etaa n dmasengmuirtin s etaotulionsm ay u ebsed .

38、4.2.6 llaPdauis mtocs koultion (Pd) = 10m g/ml. siDsolv1,2 e6 o gflap dalimurtin P ,etad(NO 3 ) 2 a ni prpxomiletay1 0 mlo f 5,6 rtin %cia c( di4.2.1)a ni 001ml vomulertcif lksad dna iult etov omule with water. 4.3.6llaP daui m soultion (P)d 1 =,m 5g/m l liDu etm 5,1lo flap dalimus tcoks o( noitul4.

39、6.21 ot )0 mlv a ni olumecirtf lsakw iht56,0 n % icirta cid.4( 2 .)2. 4.4.6 Magnuisems tos kcoultion (Mg) = 10m g/ml siDsolv1 e05, 4m gasengiumrtin (gM ,etaNO 3 ) 2 6H 2 Oi na prpxomiletay 01mlo f 5,6 n %irtcia cid( 42.)1.i na 001ml vomulertcif lksad dna iult etov omule with water. 4.5.6M agnuisem s

40、oultion (gM)m 1 = gm/ l liDu etm 1l masengmuis tkcos ooituln( 4.6)4.t om 01 li na vomulertcif lksaw ith0 ,n % 56irtci ac( di4)2.2 6.6.4 llaPdauin mitrtagam/enesiumn itrta esoultion, b ote prrapeedrppa htiw opriatv eomule of llapidamu sotuli( no4.6.3)dna m asengmuis onoitul( 4.6.5)( 1+ 1) 01 . lo feh

41、t s ouloitng ives 5,7 gP da n5 d, 0 g .gM 5 Ap tnempiuqe dna sutarap 5.1G enear l Alg llsaswraa en dplsacit rawes hla lc ebarefullyc laena denr disn deaccordni ot gp ehtrcoerud e ni NE831.40 5.2 Microwave oven, for laboratory use, checked for delivered power according to the procedure in EN 14332:20

42、04 (E) 7 6.3.2 GFAAS-determination 6.3.2.1 General Table 1 shows examples of instrumental parameters of the graphite furnace. Table 1 Graphite furnace time/temperature programme Step (#) Temperature (C) Ramp time (s) Hold time (s) Gas flow (ml/min) Gas Type Read 1 110 1 20 250 Ar 2 130 9 30 250 Ar 3

43、 1 350 12 20 250 Ar 4 2 150 fast ramp 4 stop active 5 2 450 1 3 250 Ar The absorbance is determined for an aliquot of the test solution by GFAAS. If there is no significant difference between the slope of the calibration curve in the case of the standard addition method and the external calibration

44、method, the latter can be employed. The calibration function shall consist of a minimum of 3 points including 0. NOTE 1 The date acquisition during the atomisation step can be performed by peak height or peak area measurement. When using platform technique, peak area measurement is recommended. NOTE

45、 2 Too large an injection volume may cause foaming during the drying stage, which may cause poor precision. 6.3.2.2 Standard addition method Determine the linear range of the standard calibration function. It is important that the measurements are made in the linear range when the method of standard

46、 addition is used. A standard addition curve should consist of at least three points of which at least two are standard additions. The concentration of the highest standard should be 3 to 5 times the concentration in the sample solution. The concentration of the lower standard should be half of the

47、highest standard. Plot a graph of the absorbances obtained in this way against the added concentrations and extrapolate the resulting straight line until it intercepts the concentration axis. In the case of AAS instruments with automatic sample injection systems, in which the addition takes place di

48、rectly into the graphite furnace, the determination can be carried out without prior dilution and the risk of contamination will be significantly reduced. 6.4 Analytical quality control For analytical quality control, blank solutions and reference samples having reliably known contents of arsenic to be determined shall be analysed in parallel with all the series of samples analysed according to EN 13804. The reference samples and the blank solutions shall be subjected to all the steps in the method,