EN 15765-2009 en Foodstuffs - Determination of trace elements - Determination of tin by inductively coupled plasma mass spectrometry (ICP-MS) after pressure digestion《食品 微量元素的测定 高压.pdf

1、BS EN 15765:2009ICS 67.050NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBRITISH STANDARDFoodstuffs Determination oftrace elements Determination oftin by inductivelycoupled plasma massspectrometry (ICP-MS) after pressuredigestionThis British Standardwas published under theauth

2、ority of the StandardsPolicy and StrategyCommittee on 31 January2010 BSI 2010ISBN 978 0 580 61087 5Amendments/corrigenda issued since publicationDate CommentsBS EN 15765:2009National forewordThis British Standard is the UK implementation of EN 15765:2009.The UK participation in its preparation was e

3、ntrusted 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. Users are responsible for its correct app

4、lication.Compliance with a British Standard cannot confer immunityfrom legal obligations.BS EN 15765:2009EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 15765 December 2009 ICS 67.050 English Version Foodstuffs - Determination of trace elements - Determination of tin by inductively coupled plas

5、ma mass spectrometry (ICP-MS) after pressure digestion Produits alimentaires - Dosage des lments traces - Dosage de ltain par spectromtrie de masse plasma induit par haute frquence (ICP-MS) aprs digestion sous pression Lebensmittel - Bestimmung von Elementspuren - Bestimmung von Zinn mit Massenspekt

6、rometrie mit induktiv gekoppeltem Plasma (ICP-MS) nach Druckaufschluss This European Standard was approved 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 st

7、andard without any alteration. Up-to-date lists and bibliographical references concerning such national 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 oth

8、er language made by translation under the responsibility of a CEN member into its own language and notified 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

9、, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom. EUROPEAN COMMITTEE FOR STANDARDIZATION COMIT EUROPEN DE NORMALISATION EUROPIS

10、CHES KOMITEE FR NORMUNG Management Centre: Avenue Marnix 17, B-1000 Brussels 2009 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 15765:2009: EBS EN 15765:2009EN 15765:2009 (E) 2 Contents Page Foreword 31 Scope 42 Normative referen

11、ces 43 Principle 44 Reagents .45 Apparatus and equipment 56 Procedure .67 Evaluations .78 Precision .79 Test report 8Annex A (informative) Results of the inter-laboratory test .9Bibliography . 11BS EN 15765:2009EN 15765:2009 (E) 3 Foreword This document (EN 15765:2009) has been prepared by Technical

12、 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 by publication of an identical text or by endorsement, at the latest by June 2010, and conflicting national standards s

13、hall be withdrawn at the latest by 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 Re

14、gulations, the national standards 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, Ne

15、therlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. BS EN 15765:2009EN 15765:2009 (E) 4 1 Scope This European Standard specifies a method for the determination of tin in foodstuffs by inductively coupled plasma mass spectrometry (ICP-M

16、S) after pressurized digestion. The collaborative study included carrot puree, tomato puree, pineapple, mixed fruit, white wine, peach powder, tomato powder, beans powder, powdered fruit yoghurt and fish powder foodstuffs having a mass fraction of tin ranging from 2,5 mg/kg to 259 mg/kg. 2 Normative

17、 references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. EN 13805, Foodstuffs Determination of

18、 trace elements Pressure digestion 3 Principle The sample is mineralized through pressurized digestion with nitric acid and hydrochloric acid in accordance with EN 13805. The digestion solution obtained thereby is diluted and then atomised and ionised in an inductively coupled argon plasma. After ex

19、traction from the plasma by a system of sampler and skimmer cones the positive (charged) tin ions are separated according to their mass charge ratio in a mass spectrometer and quantified in a detector system. 4 Reagents 4.1 General The concentration of tin in the reagents and water used shall be low

20、 enough not to affect the results of the determination. Solution shall be understood as an aqueous solution unless otherwise specified. 4.2 Nitric acid, mass fraction w(HNO3) 65 %, mass concentration (HNO3) 1,4 g/ml. 4.3 Hydrochloric acid, w(HCl) 30 %, density (HCl) 1,15 g/ml. 4.4 Stock solutions 4.

21、4.1 Tin stock solution, mass concentration (Sn) = 1 000 mg/l. 4.4.2 Rhodium stock solution (internal standard), mass concentration (Rh) = 1 000 mg/l. 4.5 Standard solutions 4.5.1 Tin standard solution 1, mass concentration (Sn) = 50 mg/l Fill a 50 ml volumetric flask with 10 ml to 20 ml of water, ad

22、d 2,5 ml of hydrochloric acid (4.3) and mix. Cool to ambient temperature, and add by means of a pipette exactly 2,5 ml of tin stock solution (4.4.1) and dilute to volume with water. This solution is stable for at least one week. BS EN 15765:2009EN 15765:2009 (E) 5 4.5.2 Tin standard solution 2, mass

23、 concentration (Sn) = 1,0 mg/l Fill a 50 ml volumetric flask with 10 ml to 20 ml of water, add 2,5 ml of hydrochloric acid (4.3) and mix. Cool to ambient temperature, and add by means of a pipette exactly 1,0 ml of tin standard solution 1 (4.5.1) and dilute to volume with water. This solution is sta

24、ble for one week. 4.5.3 Rhodium standard solution, mass concentration (Rh) = 10 mg/l Fill a 50 ml volumetric flask with 10 ml to 20 ml of water, add 2,5 ml of hydrochloric acid (4.3) and mix. Cool to ambient temperature, and add by means of a pipette exactly 0,5 ml of rhodium stock solution (4.4.2)

25、and dilute to volume with water. This solution is stable for at least four weeks. 4.6 Calibration solutions The following concentrations of the calibration solutions are examples and may be changed according to the sensitivity of measuring instrument and the concentration range to be investigated. C

26、are shall be taken that calibration is carried out within the linear range of the detector system while paying attention to the varying frequency of isotopes. The quantity of internal standard added should be sufficient enough to obtain a stable and reproducible intensity. For calibration at least t

27、hree calibration solutions of different concentration shall be used. The acid concentration should correspond to the one in the measuring solution. The preparation of the following solutions is given as an example: Calibration solutions with mass concentrations of 5 g/l, 10 g/l, 20 g/l and 40 g/l. T

28、he calibration solutions are prepared from the tin standard solution 2 (4.5.2) according to following procedure: Fill four 50 ml volumetric flasks with 10 ml to 20 ml of water, add 0,5 ml of nitric acid (4.2) and 0,1 ml of hydro-chloric acid (4.3) and mix. Cool to ambient temperature, and pipette ex

29、actly the same amount of internal standard, e.g. 0,5 ml of rhodium standard solution (4.5.3), into each of the measuring flasks. Then, for the calibration solutions of mass concentrations of 5 g/l, 10 g/l, 20 g/l and 40 g/l, pipette exactly 0,25 ml, 0,50 ml, 1,0 ml and 2,0 ml of the standard solutio

30、n 2 (4.5.2), respectively, into the four separate 50 ml volumetric flasks and make up to volume with water. These solutions shall be freshly prepared on each day of measurement. The calibration solutions described here shall be understood as examples. The concentrations prepared shall be in the line

31、ar range of the ICP-MS detector system. Furthermore, the acid concentration of the calibration solutions shall be matched to the amounts of acid being present in the diluted digestion solution. 4.7 Blank solution (blank solution) The blank solution contains water, nitric acid and hydrochloric acid i

32、n amounts that correspond to the concentrations in the measurement solution, for example 0,5 ml of nitric acid (4.2) and 0,1 ml of hydrochloric acid (4.3) in 50 ml as well as the same amount of internal standard (0,5 ml rhodium standard solution (4.5.3) as used for the calibration solutions in 50 ml

33、. 5 Apparatus and equipment 5.1 General All apparatus and equipment that come into direct contact with the sample and solutions shall be pre-cleaned appropriately. BS EN 15765:2009EN 15765:2009 (E) 6 5.2 ICP-MS instrument with inductively coupled argon plasma as ionisation unit, sample feeding and n

34、ebulising system as well as an instrument controlling unit and an evaluation unit. 6 Procedure 6.1 Digestion of the sample Mineralize the sample by pressurized digestion in accordance with EN 13805. For the quantification of tin, add 0,5 ml to 1 ml of hydrochloric acid (4.3) to the digestion vessel,

35、 which contains nitric acid (4.2) used for digestion, at an amount that corresponds to the amount of nitric acid. Do not add the hydrochloric acid until the spontaneous reaction with nitric acid has subsided. After addition of the hydrochloric acid close the digestion vessel immediately in order to

36、avoid loss of active chlorine. Start pressurized digestion shortly thereafter. The digestion requirements are based on the specifications of the instrument manufacturer, the reactivity of the sample, the maximum pressure stability of the digestion vessel and the attainable temperature. EXAMPLE 1 Pre

37、cisely weigh 0,4 g to 0,5 g of dry sample (residual moisture of less than 20 %) into a 100 ml digestion vessel and add 5 ml of nitric acid (4.2). Carefully shake the digestion vessel to prevent clots from forming in the sample. After the spontaneous reaction has subsided, add 1 ml of hydrochloric ac

38、id (4.3) and close the digestion vessel as quickly as possible. For samples with a higher degree of moisture content, the weighed quantities can be increased. The digestion solution that results from the pressurized digestion according to EN 13805 is made up to a defined volume, e.g. 20 ml, by water

39、. This solution is diluted, using water, by a factor of 10 or higher for the subsequent determination of tin. It is important that the amount of internal standard is exactly the same, both in the measurement solutions and in the calibrations solutions. EXAMPLE 2 For preparation of the measurement so

40、lution directly in the vessel used for measurement, pipette exactly 1,0 ml digestion solution and 0,5 ml rhodium standard solution (4.5.3) into the measurement vessel and make up with water to 10 ml. This solution should be measured on the day of preparation. 6.2 Inductively coupled plasma mass spec

41、trometry 6.2.1 ICP-MS operating conditions Set the instrument according to the manufacturers specifications and ignite the plasma. Following sufficient warming up and stabilization of the instrument, optimise the settings. 6.2.2 Determination by ICP-MS Once the instrument is optimised start the meas

42、urements. For evaluation tin isotopes of the masses 117 and 118 shall be used. The internal standard rhodium is analysed for the mass 103. Correction with internal standard is implemented by the method settings of the instrument software. Measure the blank solution (4.7) and calibration solutions (4

43、.6) and use the counting rate (counts/s) and concentrations to generate a calibration curve. Determine the linear range of the calibration function. The measurement solution is aspirated and measured. Use the calibration curve to convert the determined counting rate into concentration units. 6.3 Qua

44、lity control For quality control, analyse a reference material with reliably known content of tin in parallel to each series of measurements. Include all procedural steps starting at the digestion. This also applies to each series of digestions including all procedural steps to prepare and measure b

45、lank solutions. BS EN 15765:2009EN 15765:2009 (E) 7 7 Evaluations 7.1 Calculation of the tin content in foodstuffs Calculate the tin content, w, in milligrams per kilogram of sample or , in milligrams per litre of sample according to Equation (1): w or = 000100010001EFVa(1) where a is the mass conce

46、ntration of tin of the measurement solution, in micrograms per litre (g/l); V is the volume of the digestion solution diluted to volume, in millilitres (ml); E is the initial sample mass, in grams (g), or the initial sample volume, in millilitres (ml); F is the dilution factor ( 10). 7.2 Limit of qu

47、antification The ICP-MS instrument should be able to quantify 1 g/l tin in the diluted digestion solution. When using ICP-MS, the limit of quantification in the digestion solution prepared according to EN 13805 is mainly affected by the matrix content. Regarding the foodstuff, the limit of quantific

48、ation depends on the amount of sample used for digestion, on the final volume of digestion solution and on the minimum dilution applied (in this case 10). For trace elements the limit of quantification is conventionally defined as 6, where is the standard deviation of the field blank signal. Table 1

49、 lists relevant examples. Table 1 Examples of quantification limits in the sample Weighed quantity of sample g Final volume ml Dilution Mass fraction of tin mg/kg 0,5 20 1:10 0,42,0 20 1:10 0,18 Precision 8.1 General Details of an inter-laboratory test are summarised in Annex A. The values derived from this inter-laboratory test may not be applicable to concentration ranges and matrices other than those given in Annex A. 8.2 Repeatability The absolute difference between two independent