1、BRITISH STANDARDBS EN 12497:2005Paper and board Paper and board intended to come into contact with foodstuffs Determination of mercury in an aqueous extractThe European Standard EN 12497:2005 has the status of a British StandardICS 67.250; 85.060g49g50g3g38g50g51g60g44g49g42g3g58g44g55g43g50g56g55g3
2、g37g54g44g3g51g40g53g48g44g54g54g44g50g49g3g40g59g38g40g51g55g3g36g54g3g51g40g53g48g44g55g55g40g39g3g37g60g3g38g50g51g60g53g44g42g43g55g3g47g36g58BS EN 12497:2005This British Standard was published under the authority of the Standards Policy and Strategy Committee on 12 December 2005 BSI 12 December
3、 2005ISBN 0 580 46956 5National forewordThis British Standard is the official English language version of EN 12497:2005. It supersedes DD ENV 12497:1998 which is withdrawn.The UK participation in its preparation was entrusted by Technical Committee CW/47, Materials and articles in contact with foods
4、tuffs, to Subcommittee CW/47/3, Paper and board in contact with foodstuffs, which has the responsibility to: aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep UK interests informed;
5、 monitor related international and European developments and promulgate them in the UK.A list of organizations represented on this subcommittee can be obtained on request to its secretary.Cross-referencesThe British Standards which implement international or European publications referred to in this
6、 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 a contr
7、act. Users are responsible for its correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations.Summary of pagesThis document comprises a front cover, an inside front cover, the EN title page, pages 2 to 8, an inside back cover and a back cover.Th
8、e BSI copyright notice displayed in this document indicates when the document was last issued.Amendments issued since publicationAmd. No. Date CommentsEUROPEAN STANDARDNORME EUROPENNEEUROPISCHE NORMEN 12497August 2005ICS 67.250; 85.060 Supersedes ENV 12497:1998 English VersionPaper and board - Paper
9、 and board intended to come intocontact with foodstuffs - Determination of mercury in an aqueousextractPapier et carton - Papiers et cartons destins entrer encontact avec les denres alimentaires - Dtermination dumercure dans un extrait aqueuxPapier und Pappe - Papier und Pappe fr den Kontakt mitLebe
10、nsmitteln - Bestimmung von Quecksilber in einemwssrigen ExtraktThis European Standard was approved by CEN on 27 June 2005.CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this EuropeanStandard the status of a national standard withou
11、t any alteration. Up-to-date lists and bibliographical references concerning such nationalstandards may be obtained on application to the Central Secretariat or to any CEN member.This European Standard exists in three official versions (English, French, German). A version in any other language made
12、by translationunder the responsibility of a CEN member into its own language and notified to the Central Secretariat has the same status as the officialversions.CEN members are the national standards bodies of Austria, Belgium, Cyprus, Czech Republic, Denmark, Estonia, Finland, France,Germany, Greec
13、e, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Slovakia,Slovenia, Spain, Sweden, Switzerland and United Kingdom.EUROPEAN COMMITTEE FOR STANDARDIZATIONCOMIT EUROPEN DE NORMALISATIONEUROPISCHES KOMITEE FR NORMUNGManagement Centre: rue
14、de Stassart, 36 B-1050 Brussels 2005 CEN All rights of exploitation in any form and by any means reservedworldwide for CEN national Members.Ref. No. EN 12497:2005: EEN 12497:2005 (E) 2 Contents page Foreword 3 1 Scope .4 2 Normative references .4 3 Principle.4 4 Reagents4 4.1 General 4 4.2 Nitric ac
15、id (HNO3), 65 % (d = 1,42).4 4.2.1 Nitric acid (4.2), diluted 1 : 1 (V/V) with water .4 4.2.2 Nitric acid (4.2), diluted to 1,5 % (V/V) with water.4 4.3 Potassium permanganate (KMnO4), 5 % aqueous solution (m/V) .4 4.4 Mercury, stock solution, 1000 mg/l4 Sulphuric acid (H2SO4), (d = 1,84).5 4.6 Pota
16、ssium dichromate (K2Cr2O7), 50 g/l in sulphuric acid solution 5 4.7 Hydroxylammonium chloride (HONH3Cl), 20 g/l aqueous solution.5 4.8 Reducing solutions.5 4.8.1 Tin (II) chloride (SnCl2 2H2O), 50 g/l in 10 % hydroxhloric acid (4.9.1) 5 4.8.2 Sodium tetrahydroborate (NaBH4), 0,2 g/l in 0,05 % sodium
17、 hydroxide solution (4.10) 5 4.9 Hydrochloric acid (HCl), 36 % (d = 1,19)5 4.9.1 Hydrochloric acid (4.9) (HCl), diluted 10 % (V/V) 5 4.10 Sodium hydroxide (NaOH), 0,05 % aqueous solution (m/V) 5 5 Apparatus 5 5.1 General 5 5.2 General laboratory equipment .5 5.3 Volumetric flasks, 100 ml .5 5.4 Anal
18、ytical balance, accuracy 0,1 mg .5 5.5 Pipettes from 100 l to 10 ml, glass or plastics, (high density polyethylene/polypropylene).5 5.6 Atomic absorption spectrometer with an appropriate detection system and sensitivity6 6 Preparation of sample 6 7 Procedure 6 7.1 General 6 7.2 Preparation of refere
19、nce solution6 7.3 Determination of mercury.6 7.3.1 General 6 7.3.2 Standard additions7 7.4 Determination of blank value .7 8 Expression of results7 9 Precision8 10 Test report .8 EN 12497:2005 (E) 3 Foreword This European Standard (EN 12497:2005) has been prepared by Technical Committee CEN/TC 172 “
20、Pulp, paper and board”, 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 February 2006, and conflicting national standards shall be withdrawn at the latest
21、by February 2006. This European Standard supersedes ENV 12497:1998. With regard to ENV 12497:1998 the following changes have been made: a) implementation in a European Standard; b) addition of the clause “Precision“; c) editorial updating. According to the CEN/CENELEC Internal Regulations, the natio
22、nal standards organizations of the following countries are bound to 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, Por
23、tugal, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EN 12497:2005 (E) 4 1 Scope This European Standard is one in a series of standards for the determination of heavy metals in an aqueous extract of paper and paperboard intended for contact with food. This European Standard spec
24、ifies the test method for the determination of mercury in an aqueous extract. It is applicable to paper and board with extractable mercury content exceeding 0,06 mg per kg. NOTE 1 The above limit of determination is 5 times below the actual limit existing today or proposed in Europe. NOTE 2 Mercury
25、content levels below 0,06 mg per kg can be measured by this European Standard, if very sensitive equipment is available and if all other laboratory conditions fulfil the requirements for trace element analysis. 2 Normative references The following referenced documents are indispensable for the appli
26、cation of this European Standard. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 645, Paper and board intended to come into contact with foodstuffs Preparation of a cold water extract
27、EN 647, Paper and board intended to come into contact with foodstuffs Preparation of a hot water extract 3 Principle An aliquot portion of the stabilized cold water (see EN 645) or stabilized hot water extract (see EN 647) (see Clause 6) is analysed by atomic absorption spectrometry using cold vapou
28、r generation. 4 Reagents 4.1 General All reagents and the water used shall be suitable for trace element analysis. Store the solutions in high-density polyethylene/polypropylene bottles. 4.2 Nitric acid (HNO3), 65 % (d = 1,42) 4.2.1 Nitric acid (4.2), diluted 1 : 1 (V/V) with water 4.2.2 Nitric acid
29、 (4.2), diluted to 1,5 % (V/V) with water 4.3 Potassium permanganate (KMnO4), 5 % aqueous solution (m/V) NOTE Potassium permanganate solution is used to prepare the mercury stock solution. It is not needed if a commercially available standard solution is used (see 4.4). 4.4 Mercury, stock solution,
30、1000 mg/l Warning: Mercury is toxic. EN 12497:2005 (E) 5 Dissolve 1,080 g of mercury(II)oxide (HgO) in the minimum volume of nitric acid (4.2.1). Add 0,2 ml of potassium permanganate solution (4.3) and make up to 1000 ml with water. NOTE Commercially available standard solutions can be used if prefe
31、rred. 4.5 Sulphuric acid (H2SO4), (d = 1,84) 4.6 Potassium dichromate (K2Cr2O7), 50 g/l in sulphuric acid solution Warning: Potassium dichromate is carcinogenic. Dissolve 5 g of potassium dichromate in 80 ml of water. Add with caution 5 ml of sulphuric acid (4.5) and dilute with water to 100 ml. 4.7
32、 Hydroxylammonium chloride (HONH3Cl), 20 g/l aqueous solution Dissolve 5 g of hydroxylammonium chloride in 250 ml of water. 4.8 Reducing solutions 4.8.1 Tin (II) chloride (SnCl2 2H2O), 50 g/l in 10 % hydroxhloric acid (4.9.1) 4.8.2 Sodium tetrahydroborate (NaBH4), 0,2 g/l in 0,05 % sodium hydroxide
33、solution (4.10) NOTE Either tin chloride or sodium tetrahydroborate should be used depending on the type of spectrometer. It is recommended to follow the instructions provided by the manufacturer of the instrument. 4.9 Hydrochloric acid (HCl), 36 % (d = 1,19) 4.9.1 Hydrochloric acid (4.9) (HCl), dil
34、uted 10 % (V/V) NOTE Hydrochloric acid is used only together with tin (II) chloride (see 4.8.1 and 7.3.1). 4.10 Sodium hydroxide (NaOH), 0,05 % aqueous solution (m/V) NOTE Sodium hydroxide solution is used only together with sodium tetrahydroborate (see 4.8.2 and 7.3.1). 5 Apparatus 5.1 General All
35、flasks, pipettes etc. have to be washed with nitric acid before use and stored in dilute nitric acid (4.2.2) until required. Rinse with demineralized water before use. 5.2 General laboratory equipment 5.3 Volumetric flasks, 100 ml 5.4 Analytical balance, accuracy 0,1 mg 5.5 Pipettes from 100 l to 10
36、 ml, glass or plastics, (high density polyethylene/polypropylene) EN 12497:2005 (E) 6 5.6 Atomic absorption spectrometer with an appropriate detection system and sensitivity 6 Preparation of sample Prepare a cold water or a hot water extract from the paper or board using the test methods described i
37、n EN 645 or EN 647 respectively. Carry out two parallel extractions. Stabilize the extract by adding nitric acid (4.2) in the ratio of 3,5 ml per 100 ml of extract. Store the extract in glass bottles and analyze as soon as possible because the extract is not stable. Decrease of concentration within
38、two weeks is observed. Add potassium dichromate solution (4.6) to a content of approximately 10 mg of potassium dichromate per 100 ml of extract. NOTE Organic mercury compounds will not respond to the flameless technique unless they are decomposed into mercury(II)ions. Potassium dichromate oxidizes
39、these compounds. 7 Procedure 7.1 General Absorb the exhaust from the spectrometer in a suitable mercury absorbent. The following solution is suitable: Iodide 2,5 g; Potassium iodide 30 g; Make up to 100 ml with water. 7.2 Preparation of reference solution Prepare the reference solution daily. Dilute
40、 the stock solution (4.4) with nitric acid (4.2.2) to the appropriate concentration. A concentration of 10,0 g/l is usually appropriate. 7.3 Determination of mercury 7.3.1 General Carry out at least two parallel determinations from each stabilized extract (see Clause 6). Add 4 ml of hydroxyl ammoniu
41、m chloride solution (4.7) per 100 ml of extract to inactivate the surplus of potassium dichromate. Follow the instructions given by the manufacturer of the spectrometer in order to reduce the mercury (II) ions to mercury. The reducing agent to be used is either tin (I)chloride (4.8.1) or sodium tetr
42、ahydroborate (4.8.2), and the appropriate amount is specified in the instructions. The details of the measurement depends on the type of spectrometer. Follow the instructions and record the mercury peak. EN 12497:2005 (E) 7 7.3.2 Standard additions The matrix of some samples is such that it is impos
43、sible to record the mercury peak. In such a case the standard addition method may be useful. The following is a guide to the application of standard additions: stabilized extract 50 ml; stabilized extract 50 ml + (M) mg mercury; stabilized extract 50 ml + (2M) mg mercury. (M) represents a known mass
44、 of mercury added by using a suitable volume of the mercury stock solution (4.4) and (2M) represents double this volume. The masses selected shall give clear readings on the instrument. Follow the further instructions provided in 7.3.1 7.4 Determination of blank value Submit the water and reagents u
45、sed for the extraction to the test procedure to provide a blank value to be deducted from the extract value. NOTE Although not deprecated, the extract should only be supplied to the laboratory together with the water used for the extraction. Without this, no blank can be determined and therefore not
46、 deducted from the extract value. If a partial blank is determined this should be reported. 8 Expression of results Calculate the results with a computer or graphically. Take the blank value into consideration in the evaluation. Express the results in mg/kg or mg/dm of paper. Calculate the mercury c
47、ontent of the sample (Cmsee formula (1), Cssee formula (2) as follows: 1000110010010m=fGVCC (1) 1001100001000sbGVCC = (2) where: Cm amount of mercury soluble of the sample in mg/kg; Csamount of mercury soluble of the sample in mg/dm2; C concentration of mercury read from the calibration graph, in g/
48、l; V0total volume of extract, in ml; b grammage, in g/m2; f moisture content of the sample, in %; G mass of the sample taken under the same condition as grammage, in g. NOTE 1 The extractable mercury content of the original paper or board can be calculated if data are available. EN 12497:2005 (E) 8
49、NOTE 2 Trace element determinations are sensitive to a number of sources of error. It is, therefore, recommended to check the performance of the system by running standard reference materials. Special attention should be paid to factors such as high blank levels caused by impure reagents or modifiers, contamination during handling of the solutions, adsorption on the walls of vessels, inadequate background correction or unmatched acid concentrations of sample and calibration solutions. The detection limit should be e
