DIN EN 16801-2016 Foodstuffs - Determination of elements and their chemical species - Determination of methylmercury in foodstuffs of marine origin by isotope dilution GC-ICP-MS Ge.pdf

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1、July 2016 English price group 11No part of this translation 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 67.120.30!%XL“2534127www.din.deDIN

2、EN 16801Foodstuffs Determination of elements and their chemical species Determination of methylmercury in foodstuffs of marine origin by isotope dilution GC-ICP-MS; English ersion EN 16801:2016,English translation of DIN EN 16801:2016-07Lebensmittel Bestimmung von Elementen und ihren Verbindungen Be

3、stimmung von Methylquecksilber in Lebensmitteln marinen Ursprungs mit Isotopenverdnnung GC-ICP-MS;Englische Fassung EN 16801:2016,Englische bersetzung von DIN EN 16801:2016-07Produits alimentaires Dtermination des lments et de leurs espces chimiques Dtermination de la teneur en mthylmercure dans les

4、 produits alimentaires dorigine marinepar CG-ICP-SM avec dilution isotopique;Version anglaise EN 16801:2016,Traduction anglaise de DIN EN 16801:2016-07www.beuth.deDocument comprises 16 pagesDTranslation by DIN-Sprachendienst.In case of doubt, the German-language original shall be considered authorit

5、ative.06.16vDIN EN 16801:2016-07 2 A comma is used as the decimal marker. National foreword This document (EN 16801:2016) has been prepared by Technical Committee CEN/TC 275 “Food analysis Horizontal methods” (Secretariat: DIN, Germany). The responsible German body involved in its preparation was DI

6、N-Normenausschuss Lebensmittel und landwirtschaftliche Produkte (DIN Standards Committee Food and Agricultural Products), Working Committee NA 057-01-09 AA Elemente und ihre Verbindungen. The DIN Standards corresponding to the International Standards referred to in this document are as follows, wher

7、eby EN ISO Standards are only listed below if these have not been published as DIN EN ISO Standards with the same number: EN ISO 3696 DIN ISO 3696 ISO 5725-2 DIN ISO 5725-2 National Annex NA (informative) Bibliography DIN ISO 3696, Water for analytical laboratory use Specification and test methods D

8、IN ISO 5725-2, Accuracy (trueness and precision) of measurement methods and results Part 2: Basic method for the determination of repeatability and reproducibility of a standard measurement method EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 16801 March 2016 ICS 67.120.30 English Version Foo

9、dstuffs - Determination of elements and their chemical species - Determination of methylmercury in foodstuffs of marine origin by isotope dilution GC-ICP-MS Produits alimentaires - Dtermination des lments et de leurs espces chimiques - Dtermination de la teneur en mthylmercure dans les produits alim

10、entaires dorigine marine par dilution isotopique CG-ICP-SM Lebensmittel - Bestimmung von Elementen und ihren Verbindungen - Bestimmung von Methylquecksilber in Lebensmitteln marinen Ursprungs mit Isotopenverdnnung GC-ICP-MS This European Standard was approved by CEN on 8 February 2016. CEN members a

11、re 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 national standards may be obtained on application to

12、 the CEN-CENELEC 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 notified to the CEN-CENELEC Management C

13、entre has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithu

14、ania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey andUnited Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPISCHES KOMITEE FR NORMUNG CEN-CENELEC Management Centre: Avenue Marnix 17, B-1

15、000 Brussels 2016 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 16801:2016 EEN 16801:2016 (E) 2 Contents Page European foreword . 3 1 Scope 4 2 Normative references 4 3 Principle . 4 4 Reagents . 4 5 Apparatus and equipment . 6 6

16、 Procedure. 7 7 Calculation 10 8 Precision 11 9 Test report 12 Annex A (informative) Precision data . 13 Bibliography . 14 DIN EN 16801:2016-07 EN 16801:2016 (E) 3 European foreword This document (EN 16801:2016) has been prepared by Technical Committee CEN/TC 275 “Food analysis - Horizontal methods”

17、, 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 September 2016, and conflicting national standards shall be withdrawn at the latest by September 2016. At

18、tention 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. This document has been prepared under mandate M 422 given to CEN by the European Commiss

19、ion and the European Free Trade Association. According to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, Forme

20、r Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the United Kingdom. DIN EN 16801:2016-07 EN 16801:2016 (E) 4 1

21、 Scope This European Standard describes a method for the determination of monomethylmercury (MMHg) in foodstuffs of marine origin. The method has been validated in an interlaboratory test on mussel tissue, squid muscle, crab claw muscle, dog fish liver, whale meat, cod muscle and Greenland halibut m

22、uscle (all freeze-dried) with mass fractions from 0,04 mg/kg to 3,6 mg/kg dry weight according to ISO 5725-2 1. Laboratory experiences have shown that this method is also applicable on fresh samples 2. 2 Normative references The following documents, in whole or in part, are normatively referenced in

23、 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 13804, Foodstuffs Determination of elements and their chemical species General

24、considerations and specific requirements EN ISO 3696, Water for analytical laboratory use Specification and test methods (ISO 3696) 3 Principle The sample is spiked with an appropriate amount of Hg-isotope enriched MMHg and digested using tetramethylammonium hydroxide (TMAH). After pH adjustment, de

25、rivatisation and extraction, the organic phase is analysed using GC-ICP-MS. The GC separates the different mercury species before the derivatised species (ethylmethylmercury) is atomised and ionised in the high temperature by the ICP. The ions are extracted from the plasma by a set of sampler and sk

26、immer cones and transferred to a mass spectrometer where the ions are separated by their mass/charge ratio and determined by a pulse-count and/or analogue detector. The result is calculated using the isotope dilution equation. WARNING The use of this method may involve hazardous materials, operation

27、s 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 safety and health practices and determine the applicability of regulatory limitations prior to use. 4 Reagents 4.1 Ge

28、neral The concentration of mercury species in the reagents and water used shall be low enough to not affect the results of the determination. When using a method of high sensitivity like ICP-MS, the control of the blank levels of water, acid and other reagents is very important. Generally ultra-pure

29、 water complying with ISO 3696 grade 1 (i.e. electrical conductivity below 0,1 S/cm at 25 C) and acid of high purity is recommended, e.g. cleaned by sub-boiling distillation. Reagents should be of minimum p.a. quality where possible. Special facilities can be used in order to avoid contamination dur

30、ing the steps of preparation and measurement (e.g. uses of laminar flow benches or comparable clean room facilities). DIN EN 16801:2016-07 EN 16801:2016 (E) 5 4.2 Monomethylmercury stock solutions. Commercially available MMHg standard enriched in the 201Hg-isotope with a mass fraction of 5,5 g/g (as

31、 Hg) is recommended, such as IES-MMHg2011). Other MMHg Hg-isotope enriched standards may also be available in suitable mass fractions from other suppliers or may be prepared in-house. In this case, the method shall be adjusted accordingly. The quality of the standards should be designed to be used b

32、y isotope dilution methods. Stock solutions in diluted acid are preferred. 4.3 Monomethylmercury standard solution. 4.3.1 General The mass fractions of the MMHg in the standard solutions shall be chosen in relation to the expected mass fraction of MMHg in samples. It is important that all dilutions

33、are done by weighing so that their accurate mass fractions can be calculated. The following descriptions are given as examples. 4.3.2 MMHg approximately 500 ng/g (as Hg). Dilute approximately 1 g, to the nearest milligram, of 201Hg enriched MMHg stock solution (4.2) with water up to 10 g. Calculate

34、the exact mass fraction using the mass fraction of the stock solution and weight. 4.3.3 MMHg approximately 50 ng/g (as Hg). Dilute approximately 1 g, to the nearest milligram, of the 500 ng/g 201Hg enriched MMHg solution (4.3.2) with water up to 10 g. Calculate the exact mass fraction using the exac

35、t mass fraction of the 500 ng/g solution and weights. 4.3.4 MMHg approximately 5 ng/g (as Hg). Dilute approximately 1 g, to the nearest milligram, of the 50 ng/g 201Hg enriched MMHg solution (4.3.3) with water up to 10 g. Calculate the exact mass fraction using the exact mass fraction of the 50 ng/g

36、 solution and weights. 4.4 Tetramethylammonium hydroxide (TMAH), mass fraction w = 25 % in water, minimum synthesis quality. 4.5 Acetic acid, concentrated, mass concentration = 1,05 g/ml, minimum p.a. quality. 4.6 Sodium hydroxide, minimum p.a. quality. 4.7 Sodium hydroxide solution, substance conce

37、ntration c(NaOH) = 0,1 mol/l. Transfer 0,4 g of sodium hydroxide to a 100 ml volumetric flask and add water to the mark. 4.8 Sodium acetate, minimum p.a. quality. 4.9 Sodium acetate/acetic acid buffer (pH 5). Dissolve 41 g of sodium acetate in approximately 0,5 l of water. Adjust the pH of the solut

38、ion to 5 by adding concentrated acetic acid (4.5) dropwise by using a pH-meter (5.4). Finally, dilute the solution to 1 l with water. 1) IES-MMHg201 is available from e.g. Innovative Solutions in Chemistry S.L., Edificio Cientfico-Tecnolgico, Campus de “El Cristo“, 33006, Oviedo, Spain http:/www.isc

39、- or Qmx Laboratories, bolford Street, Thaxted, Essex, CM6 2PY, UK http:/ This is an example of a suitable product available commercially. This information is given for the convenience of the users of this International Standard and does not constitute an endorsement by CEN of this product. DIN EN 1

40、6801:2016-07 EN 16801:2016 (E) 6 4.10 Nitric acid, 65 %, of approximately 1,4 g/ml. Hg-free quality. Other acid concentrations may be used if the volume added in 6.2 is adjusted accordingly. 4.11 Sodium tetraethyl borate, minimum synthesis quality (98 %). 4.12 Sodium tetraethyl borate solution (2 %)

41、. Dissolve 1 g of sodium tetraethyl borate in 0,1 mol/l of sodium hydroxide solution (4.7), transfer to a 50 ml-volumetric flask and fill up to the mark with 0,1 mol/l sodium hydroxide solution. Prepare freshly at each day of analysis or divide the solution into smaller amounts and store in the free

42、zer at approximately 20 C. The solution may be stored at approximately 20 C for at least three months. The solution shall be used within the day after removal from the freezer. 4.13 Hexane, minimum HPLC-quality. 4.14 Optimising solution for the ICP-MS. The optimising solution should contain elements

43、 that cover the whole mass range giving a high rate of oxides and doubly charged ions. Use the solutions recommended by the manufacturer of the ICP-MS instrument. A solution containing e.g. Li, Ce and Tl is suitable for those purposes. In this case, choose the concentration of these elements in orde

44、r to achieve a count rate of 10 000 cps (counts per second). 5 Apparatus and equipment All pieces of equipment described here are examples of suitable equipment and may be replaced by equivalent equipment unless otherwise stated. Generally, clean and rinse the vessels carefully according to the proc

45、edure in EN 13804. In addition to standard laboratory equipment, use the following: 5.1 Analytical balance, accuracy of 0,5 mg. 5.2 Orbital/overhead rotator, capable of approximately 0,04 g (20 min1). 5.3 Centrifuge, capable of 1 200 g (4 000 min1). 5.4 pH-meter. 5.5 Laboratory ware, volumetric flas

46、ks of glass, polypropylene tubes (10 ml) for samples, GC-vials, pH paper. 5.6 Inductively Coupled Plasma Mass Spectrometer (ICP-MS). Mass spectrometer with inductively coupled argon plasma operating in a mass range from 5 amu (atomic mass units) to 240 amu. Using routine settings the mass spectromet

47、er shall be capable to resolve 1 amu peak width at 5 % peak height or better (resolution 300) with sufficient sensitivity to achieve the detection limits suitable for the analytical purpose. 5.7 Argon, purity 99,99 %. 5.8 Gas chromatograph (GC), with injector heating, programmable column heating and

48、 heating of transfer line to ICP-MS. 5.9 GC-column, capillary or preparative column capable of separating ethylmethylmercury from other mercury species (e.g. 30 m x 0,32 mm, analytical column with 5 % phenyl methyl siloxane; film thickness: 0,25 m). DIN EN 16801:2016-07 EN 16801:2016 (E) 7 5.10 Heli

49、um, purity 99,99 %. 5.11 Helium, (5.10) with 1 % to 2 % added xenon for tuning of the GC-ICP-MS interface or some other tuning configuration capable of optimising the instrument parameters, optional. 5.12 Oxygen, optional, to prevent carbon deposition, according to manufacturers instructions, e.g. 5 %. 6 Procedure 6.1 Calculation of optimal spike amount The following description is given for the 201Hg enriched MMHg spike solution (4.2). To ensure that the measurement is within acceptable error