EN 15764-2009 en Foodstuffs - Determination of trace elements - Determination of tin by flame and graphite furnace atomic absorption spectrometry (FAAS and GFAAS) after pressure di.pdf

1、BS EN 15764:2009ICS 67.050NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBRITISH STANDARDFoodstuffs Determination oftrace elements Determination oftin by flame andgraphite furnaceatomic absorptionspectrometry (FAASand GFAAS) afterpressure digestionThis British Standardwas publ

2、ished under theauthority of the StandardsPolicy and StrategyCommittee on 31 January2010 BSI 2010ISBN 978 0 580 61086 8Amendments/corrigenda issued since publicationDate CommentsBS EN 15764:2009National forewordThis British Standard is the UK implementation of EN 15764:2009.The UK participation in it

3、s 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. Users are responsible

4、for its correct application.Compliance with a British Standard cannot confer immunityfrom legal obligations.BS EN 15764:2009EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 15764 December 2009 ICS 67.050 English Version Foodstuffs - Determination of trace elements - Determination of tin by flame

5、 and graphite furnace atomic absorption spectrometry (FAAS and GFAAS) after pressure digestion Produits alimentaires - Dosage des lments traces - Dosage de ltain par spectromtrie dabsorption atomique flamme (SAAF) et spectromtrie dabsorption atomique four graphite (SAAFG) aprs digestion sous pressio

6、n Lebensmittel - Bestimmung von Elementspuren - Bestimmung von Zinn mit der Flammen- und Graphitofen-Atomabsorptionsspektrometrie (FAAS und GFAAS) nach Druckaufschluss This European Standard was approved by CEN on 7 November 2009. CEN members are bound to comply with the CEN/CENELEC Internal Regulat

7、ions 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 the CEN Management Centre or to any CEN member. This Eu

8、ropean 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 Management Centre has the same status as the official versions. CEN members are the

9、national standards bodies of Austria, Belgium, Bulgaria, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland

10、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 exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 1576

11、4:2009: EBS EN 15764:2009EN 15764:2009 (E) 2 Contents Page Foreword 31 Scope 42 Normative references 43 Principle 44 Reagents .45 Apparatus and equipment 66 Procedure .77 Evaluations .98 Precision 109 Test report . 11Annex A (informative) Results of the inter-laboratory test 12Bibliography . 16BS EN

12、 15764:2009EN 15764:2009 (E) 3 Foreword This document (EN 15764:2009) 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 by publication of a

13、n identical text or by endorsement, at the latest by June 2010, and conflicting national standards shall 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

14、 responsible for identifying any or all such patent rights. 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, Cyprus, Czech Republic, Denmark, Estonia, Finland,

15、 France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. BS EN 15764:2009EN 15764:2009 (E) 4 1 Scope This European Standard specifies a meth

16、od for the determination of tin in foodstuffs and canned foods by flame and graphite furnace atomic absorption spectrometry (AAS) after pressurized digestion. The collaborative study included foodstuffs such as carrot puree, tomato puree, pineapple, mixed fruit, white wine, peach powder, tomato powd

17、er, powdered beans, powdered fruit yoghurt, fish powder, having mass fractions of tin ranging from 43 mg/kg to 260 mg/kg (Flame-AAS) and from 2,5 mg/kg to 269 mg/kg (Graphite Furnace AAS). 2 Normative references The following referenced documents are indispensable for the application of this documen

18、t. 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 trace elements Pressure digestion 3 Principle The sample is mineralized through pressurized digesti

19、on with nitric acid and hydrochloric acid in accordance with EN 13805. In the resulting digestion solution, tin is quantified by flame AAS (F-AAS) or graphite furnace AAS (GF-AAS) depending on the concentration in the sample solution. 4 Reagents 4.1 General The concentration of tin in the reagents a

20、nd water used shall be low enough not to affect the results of the determination. 4.2 Nitric acid Mass fraction w(HNO3) 65 %, mass concentration (HNO3) 1,4 g/ml. 4.3 Hydrochloric acid w(HCL) 30 %, (HCl) 1,15 g/ml. 4.4 Tin stock solution (Sn) = 1 000 mg/l. 4.5 Tin standard and calibration solutions 4

21、.5.1 General The standard and calibration solutions are prepared from the stock solution by dilution in glass volumetric flasks. For calibration, prepare at least four calibration solutions of different concentrations. The acid concen-tration shall correspond to the concentration in the measurement

22、solution. BS EN 15764:2009EN 15764:2009 (E) 5 The preparation of the solutions in 4.5.2 and 4.5.3 is given as an example. 4.5.2 Calibration solutions of (Sn) = 5 mg/l, 10 mg/l, 20 mg/l and 30 mg/l for flame AAS. Fill four 50 ml volumetric flasks with 10 ml to 20 ml of water, add 5 ml of nitric acid

23、(4.2) and 1 ml of hydrochloric acid (4.3) and mix. Cool the solutions to ambient temperature, and pipette exactly 0,25 ml, 0,50 ml, 1,00 ml and 1,50 ml of tin stock solution (4.4) for the respective calibration solutions of mass concentrations 5 mg/l, 10 mg/l, 20 mg/l and 30 mg/l into the four diffe

24、rent 50 ml volumetric flasks. Mix the solutions and dilute to volume with water. These solutions are stable for at least one day. The calibration solutions described here shall be understood as examples. The concentrations prepared shall be in the linear range of the measuring device. The acid conce

25、ntration of the calibration solutions shall be matched to the acid concentration in the sample solution. 4.5.3 Calibration solutions of (Sn) = 0,010 mg/l, 0,020 mg/l, 0,040 mg/l and 0,060 mg/l for GF-AAS. To prepare standard solution 1 (Sn) = 50 mg/l), fill a 50 ml volumetric flask with 10 ml to 20

26、ml of water, add 2,5 ml of hydrochloric acid (4.3) and mix. Cool the solution to ambient temperature, add exactly 2,5 ml of tin stock solution (4.4) and dilute to volume. This solution is stable for at least one week. To prepare standard solution 2 (Sn) = 1,0 mg/l), fill a 50 ml volumetric flask wit

27、h 10 ml to 20 ml of water, add 2,5 ml of hydrochloric acid (4.3) and mix. Cool the solution to ambient temperature, add exactly 1,0 ml of tin standard solution 1 by pipette and dilute to volume. Prepare the calibration solutions for the graphite furnace AAS from standard solution 2 according to the

28、following procedure: Fill four 50 ml volumetric flasks with 10 ml to 20 ml of water, add 5 ml of nitric acid (4.2) and 1 ml of hydro-chloric acid (4.3) and mix. Cool the solutions to ambient temperature, pipette exactly 0,50 ml, 1,0 ml, 2,0 ml and 3,0 ml of standard solution 2 for the respective cal

29、ibration solutions of mass concentrations 0,010 mg/l, 0,020 mg/l, 0,040 mg/l and 0,060 mg/l into the four different 50 ml volumetric flasks and dilute to final volume with water. These solutions shall be re-prepared for each day of measurement. The calibration solutions described here shall be under

30、stood as an example. The concentrations prepared shall be in the linear range of the measuring device. The acid concentration of the calibration solutions shall be matched to the amounts of acid used in the digestion. 4.6 Blank solution The blank solution contains water, nitric acid and hydrochloric

31、 acid in amounts that correspond to the concentrations in the measurement solution, for example 10 ml of nitric acid (4.2) and 2 ml of hydrochloric acid (4.3) in 100 ml of water. 4.7 Matrix modifiers for graphite furnace AAS 4.7.1 General Tin compounds shall be stabilized by matrix modifiers for qua

32、ntification by graphite furnace AAS during the ashing step. Different matrix modifiers are used at different concentrations. To use a suitable modifier, first consider the recommendations of the device manufacturer. Select a suitable modifier; use the sample matrix to be examined to verify the ashin

33、g temperature of the graphite furnace program and optimize it in such a way that no tin is lost in the graphite tube during the mineralization step. BS EN 15764:2009EN 15764:2009 (E) 6 In 4.7.2 to 4.7.4 an example is presented of a modifier for quantifying tin. 4.7.2 Ammonium dihydrogen phosphate so

34、lution Mass fraction w 10 %. Dissolve 10,0 g of ammonium dihydrogen phosphate (NH4H2PO4) in 100 ml of water. 4.7.3 Magnesium nitrate solution Mass concentration (Mg) = 10 g/l. Dissolve 10,5 g of magnesium nitrate hexahydrate (Mg(NO3)2 6H2O) in 100 ml of water. NOTE Commercially available solutions c

35、an also be used. 4.7.4 Matrix modifiers for quantification of tin (NH4H2PO4) = 50 g/10 l and (Mg(NO3)2) = 3 g/10 l. Pipette 2,5 ml of ammonium dihydrogen phosphate solution (4.7.2) and 0,25 ml of magnesium nitrate solution (4.7.3) into a 50 ml volumetric flask; add 1 ml of nitric acid (4.2), and dil

36、ute to volume with water. This solution remains usable for several months when refrigerated. 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. 5.2 Atomic absorption spectrometer with nitro

37、us oxide/acetylene burner and atomization system. 5.3 Atomic absorption spectrometer with background correction (Zeemann background correction is recommended), graphite tube furnace and autosampler. 5.4 Element-selective detection 5.4.1 Element-specific lamp for tin (hollow-cathode or electrodeless

38、discharge lamp). 5.4.2 Continuum radiation source with high-resolution monochromatic illuminator as an alternative to 5.4.1. The resolution of the measuring equipment at normal operation shall correspond to at least the half-width value of the emission line of the element specific lamp (usually 1 pm

39、 to 3 pm). BS EN 15764:2009EN 15764:2009 (E) 7 6 Procedure 6.1 Digestion of the sample Mineralize the sample in 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, which contains nitric acid (4.2) us

40、ed for the 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 avoid loss of active chlorine. S

41、tart 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 Precisely weigh 0,4 g to 0,5 g of dry

42、 sample (residual moisture of less than 20 %) in a 100 ml digestion vessel and mix it with 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 acid (4.3) and close the diges

43、tion 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 can be used directly or can be diluted for the subsequent quantification of tin.

44、 6.2 Flame atomic absorption spectrometry 6.2.1 General Start the instrument and let it stabilise, then optimise it according to the manufacturers specifications. Set the wavelength to 286,3 nm or 235,5 nm. The nitrous oxide/acetylene flame needs special attention. In general reducing conditions giv

45、e the best response. If deposits are formed on the burner they need to be removed before they interfere with the determination. If necessary, use background correction. 6.2.2 Quantification by flame AAS Warm up and stabilize the instrument; then begin measurements. 6.2.3 Calibration and measurement

46、Use the blank solution (4.6) to zero the instrument. Measure the calibration solutions (4.5.2) and use the extinctions (absorbance) and concentrations to generate a calibration curve. Determine the linear range of the calibration function. The measurement solution is taken up and measured. Use the c

47、alibration curve to convert the determined extinction into concentration units. For long series of measurements, verify the blank and the calibration function multiple times. 6.3 Graphite furnace atomic absorption spectrometry 6.3.1 General Set and optimize the instrument according to the manufactur

48、ers specifications. Set the wavelength to 286,3 nm. Use the manufacturers specifications to set the slit width, volumes of samples and modifiers, and the temperatures and times of the drying, ashing and atomizing steps. Adjust these parameters to the sample matrix to be examined, and optimize the as

49、hing and atomizing times and temperatures in particular. The instrument parameters depend on the type and amount of modifier used, the type of graphite tube heating and the settings that are recommended by the manufacturer and that result from direct optimization. BS EN 15764:2009EN 15764:2009 (E) 8 NOTE The wavelength of 235,5 nm can be used, but was not tested in the collaborative trial. 6.3.2 Calibration and measurement 6.3.2.1 General Check if the standard curve and the standard addition cur