EN 15763-2009 en Foodstuffs - Determination of trace elements - Determination of arsenic cadmium mercury and lead in foodstuffs by inductively coupled plasma mass spectrometry (ICP.pdf

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1、BS EN 15763:2009ICS 67.050NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBRITISH STANDARDFoodstuffs Determination oftrace elements Determination ofarsenic, cadmium,mercury and leadin foodstuffs byinductively coupledplasma massspectrometry (ICP-MS) after pressuredigestionThis B

2、ritish Standardwas published under theauthority of the StandardsPolicy and StrategyCommittee on 31 January2010 BSI 2010ISBN 978 0 580 61085 1Amendments/corrigenda issued since publicationDate CommentsBS EN 15763:2009National forewordThis British Standard is the UK implementation of EN 15763:2009.The

3、 UK participation in its preparation was entrusted to TechnicalCommittee AW/-/3, Food analysis - Horizontal methods.A list of organizations represented on this committee can be obtained onrequest to its secretary.This publication does not purport to include all the necessary provisionsof a contract.

4、 Users are responsible for its correct application.Compliance with a British Standard cannot confer immunityfrom legal obligations.BS EN 15763:2009EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 15763 December 2009 ICS 67.050 English Version Foodstuffs - Determination of trace elements - Determ

5、ination of arsenic, cadmium, mercury and lead in foodstuffs by inductively coupled plasma mass spectrometry (ICP-MS) after pressure digestion Produits alimentaires - Dosage des lments traces - Dosage de larsenic, du cadmium, du mercure et du plomb par spectromtrie dmission avec plasma induit par hau

6、te frquence et spectromtre de masse (ICP-MS) aprs digestion sous pression Lebensmittel - Bestimmung von Elementspuren - Bestimmung von Arsen, Cadmium, Quecksilber und Blei in Lebensmitteln mit induktiv gekoppelter Plasma-Massenspektrometrie (ICP-MS) nach Druckaufschluss This European Standard was ap

7、proved by CEN on 7 November 2009. CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such natio

8、nal standards may be obtained on application to the CEN Management Centre or to any CEN member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CEN member into its own language and n

9、otified to the CEN Management Centre has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg,

10、 Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels 2009 CEN All rights of

11、exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 15763:2009: EBS EN 15763:2009EN 15763:2009 (E) 2 Contents Page Foreword 31 Scope 42 Normative references 43 Principle 44 Reagents .45 Apparatus and equipment 66 Procedure .67 Calculation . 108 Analytic

12、al quality control . 119 Limit of quantification 1110 Precision 1111 Test report . 13Annex A (informative) Results of the collaborative test . 14Bibliography . 18BS EN 15763:2009EN 15763:2009 (E) 3 Foreword This document (EN 15763:2009) has been prepared by Technical Committee CEN/TC 275 “Food analy

13、sis - Horizontal methods”, the secretariat of which is held by DIN. 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 June 2010, and conflicting national standards shall be withdrawn at the latest b

14、y June 2010. 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 responsible for identifying any or all such patent rights. According to the CEN/CENELEC Internal Regulations, the national standards

15、 organizations of 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, Portug

16、al, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. BS EN 15763:2009EN 15763:2009 (E) 4 1 Scope This European Standard specifies a method for the determination of arsenic, cadmium, mercury and lead in foodstuffs by inductively coupled plasma mass spectrometry (ICP-MS)

17、. The collaborative study included foodstuffs such as carrots, fish homogenate, Mushrooms (CRM), graham flour, a simulated diet E (CRM), scampi, mussel and a Tort-2 CRM having an arsenic mass fraction ranging from 0,06 mg/kg to 21,5 mg/kg dry matter (d. m.), cadmium ranging from 0,03 mg/kg to 28,3 m

18、g/kg d. m., mercury ranging from 0,04 mg/kg to 0,56 mg/kg d. m. and lead from 0,01 mg/kg to 2,4 mg/kg d. m. 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,

19、the latest edition of the referenced document (including any amendments) applies. EN 13805, Foodstuffs Determination of trace elements Pressure digestion 3 Principle The test solution, obtained by pressure digestion, is nebulised and the aerosol transferred to a high frequency inductively coupled ar

20、gon plasma. The high temperature of the plasma is used to dry the aerosol and to atomise and ionise the elements. The ions are extracted from the plasma by a set of sampler and skimmer cones and transferred to a mass spectrometer where the ions are separated by their mass/charge ratio and determined

21、 by a pulse-count and/or analogue detector. WARNING The use of this method may involve hazardous materials, operations and equipment. This method does not purport to address all the safety problems associated with its use. It is the responsibility of the user of this method to establish appropriate

22、safety and health practices and determine the applicability of regulatory limitations prior to use. 4 Reagents 4.1 General The concentration of the trace elements in the reagents and water used shall be low enough not to affect the results of the determination. Using a multielemental method of high

23、sensitivity like ICP-MS, the control of the blank levels of water and acid is very important. Generally ultrapure water and acid of high purity, e.g. cleaned by sub boil distillation, are recommended. Special facilities should be used in order to avoid contamination during the steps of preparation a

24、nd measurements (e.g. use of laminar flow benches or comparable clean room facilities). 4.2 Nitric acid Mass fraction not less than w(HNO3) = 65 %, with a density of approximately 1,4 g/ml. BS EN 15763:2009EN 15763:2009 (E) 5 4.3 Element stock solutions Commercially available single or multielementa

25、l standards with a mass concentration of = 1 000 mg/l of As, Au, Cd, Hg, Lu, Rh and Pb are recommended. Such standards are available in suitable concentrations from different suppliers. Stock solutions in diluted nitric acid are preferred. 4.4 Diluted mercury stock solution, (Hg) = 10 mg/l Pipette 1

26、 ml of Hg stock solution of (Hg) = 1 000 mg/l (4.3) and 1 ml of nitric acid (4.2) in a 100 ml volumetric flask and dilute with water to mark. 4.5 Diluted multi-element stock solution The concentration levels of the elements in the diluted multi-element stock solution may be chosen in the relation to

27、 the type of samples analysed. EXAMPLE (As) = 20 mg/l, (Cd), (Pb) = 10 mg/l. Pipette 2 ml of As, 1 ml of Cd and Pb, respectively of each stock solution into a 100 ml volumetric flask , add 1 ml of nitric acid (4.2), dilute with water to the mark and transfer the solution into a suitable vessel. 4.6

28、Multi-element calibration solution According to the example given under 4.5, the multi-element calibration solution contains: = 100 g/l As, = 50 g/l Cd, Hg, Pb. Pipette 0,5 ml diluted mercury stock solution (4.4) and 0,5 ml of the diluted multi-element stock solution (4.5) to a 100 ml volumetric fla

29、sk, add 1 ml nitric acid (4.2), dilute with water to the mark and transfer the solution into a suitable vessel (PFA or quartz is recommended). 4.7 Internal standard solution The internal standard solution contains Rhodium and Lutetium with a mass concentration of = 1 000 mg/l. Gold is used to stabil

30、ise mercury in the solution and reduce memory effects. The internal standard/s should cover the mass range used for determination of the elements. Their concentrations in the test solutions should be negligible. 4.8 Diluted internal standard solution The concentration of the diluted internal standar

31、d solution should be high enough to give sufficient signal intensity. For an internal standard solution of (Au, Rh, Lu) = 5 mg/l, pipette 0,5 ml of Au, Rh and Lu internal standard solution (4.7) each into a 100 ml flask, add 1 ml of nitric acid (4.2), dilute to volume with water and transfer the sol

32、ution into a suitable vessel. 4.9 Optimising solution The optimising solution is used for check and optimising procedures during set up of the ICP-MS. It is used for mass calibration purposes and for adjustment of maximum sensitivity at low rates of oxides and doubly charged ions. The optimising sol

33、ution should contain elements that cover the whole mass range giving a high rate of oxides and doubly charged ions. The solutions recommended by the manufacturer of the ICP-MS instrument may be used. A solution containing e.g. Y, Rh, Ce and Pb is suitable for those purposes. The concentration of the

34、se elements should be chosen in order to achieve a count rate of 10 000 to 100 000. 4.10 Blank solution The blank solution contains water and the same amount of acid used in the calibration solution. BS EN 15763:2009EN 15763:2009 (E) 6 5 Apparatus and equipment 5.1 General Stability of test and dilu

35、ted stock solutions are greatly influenced by the material of which the storage vessel is made. For the determination of elements in trace or ultra trace concentrations vessels made of quartz or fluoropolymers (polytetrafluoroethylene PTFE, perfluoroalkoxy PFA) are highly recommended. Glass or polyv

36、inylchloride (PVC) should not be used. Vessels made of other materials may be used as long as they do not affect the results. The vessels should be carefully cleaned and rinsed. 5.2 Inductively Coupled Plasma Mass Spectrometer (ICP-MS) Mass spectrometer with inductively coupled argon plasma operatin

37、g in a mass range from 5 amu to 240 amu. Using routine settings the mass spectrometer shall be capable to resolve 1 amu peak width at 5 % peak height or better (resolution 300) and have a sensitivity to achieve the detection limits listed in Table 2. Mass spectrometers with additional reaction or co

38、llision cells may be used to reduce the influence of polyatomic ions. Sectorfield mass spectrometers that allow the separation of the polyatomic ions by the use of high resolution settings may also be used. The ICP-MS, having a nebulising system with a low pulsion peristalic pump, should be equipped

39、 with a mass flow controller for the nebuliser gas. 5.3 Argon Purity of at least 99,99 %. 6 Procedure 6.1 Sample pretreatment Food samples are treated by a pressure digestion method according to EN 13805. The digested solution is diluted by water to a known volume (test solution). The concentration

40、of nitric acid used in the calibration solutions should be similar to the final concentrations of nitric acid in the test solution. If hydrogen peroxide was added for the digestion, the calibration solutions need no addition of hydrogen peroxide. 6.2 ICP-MS 6.2.1 General The correlation between the

41、concentration of the element and the count rate measured is linear over some orders of magnitude. Therefore linear calibration functions can be used. The concentration range of the linearity should be checked regularly for each element. ICP-MS instruments with dual-detector capabilities, having an e

42、xtended linear range, additionally need a regular check of the cross calibration factor of the two detectors. BS EN 15763:2009EN 15763:2009 (E) 7 6.2.2 ICP-MS settings Table 1 Example of instrument settings for ICP-MS Parameter Setting RF-Power (W) 1 500 Carrier gas flow (l/min) 1,2 Plasma gas flow

43、(l/min) 15 Auxiliary gas flow (l/min) 1,0 Spray chamber Water cooled double pass Spray chamber temperature (C) 2 Lens voltage 4,5 Mass resolution 0,8 Integration time points/ms 3 Points per peak 3 Replicates 3 The instrument parameters described in the manufacturers operating manual should be used.

44、Generally, a plasma power of 1 100 W to 1 500 W should be chosen. By use of shorter or longer integration times on the isotope, the sensitivity may be influenced in some extend. Generally, three repeated measurements of each solution should be done. An example of instrument settings is given in Tabl

45、e 1. 6.2.3 Set up procedures for the ICP-MS Before starting routine measurements the following set up procedure should be run: The ICP-MS should warm up in full running mode for a minimum 20 min to 30 min. Mass resolution, mass calibration, sensitivity and stability of the system are checked by the

46、use of a suitable optimising solution (4.9). With an optimising solution the ICP-MS is adjusted daily to achieve maximum ion signals and both low oxide rates (e.g. 2 %) and low rates of doubly charged ions (e.g. 2 %). If a collision or reaction cell instrument is used, the flow rate of the cell gas(

47、es) should be optimised, in order to ensure sufficient reduction of polyatomic interferences. If a high resolution mass spectrometer is used, mass calibration and sensitivity shall be checked for every range of resolution used. Check the sample feed and washout times with respect to the length of th

48、e tubing. If large differences in concentration of the test solutions are expected, the sample feed and washout times should be prolonged. 6.3 Interferences 6.3.1 General Different types of interferences can influence the results obtained by ICP-MS measurements. Non-spectral interferences are caused

49、 by e.g. viscosity and the amount of matrix of the test solution. High amounts of salt can lead to deposition effects especially in the cone system. Generally the amount of salt in the test solution should not exceed 0,2 % (mass fraction). By the use of internal standards some of the non-spectral interference effects can be corrected for. Memory effects in the sample delivery system can influence the results of samples analysed after measurement of high concentrations. Especially high concen