1、BRITISH STANDARD BS EN ISO 11212-1:1997 Starch and derived products Heavy metals content Part 1: Determination of arsenic content by atomic absorption spectrometry The European Standard EN ISO 11212-1:1997 has the status of a British Standard ICS 67.180.20BSENISO 11212-1:1997 This British Standard,
2、having been prepared under the direction of the Consumer Products and Services Sector Board, was published under the authority of the StandardsBoard and comes into effect on 15 April 1997 BSI 01-1999 ISBN 0 580 27458 6 National foreword This British Standard is the English language version of EN ISO
3、 11212-1:1997. It is identical with ISO 11212-1:1997 and implements it as the UK national standard. This British Standard has been produced to fulfil BSIs obligation to implement all European Standards but, because of the absence of interest in the UK in the subject concerned, there has been no UK p
4、articipation in the preparation of EN ISO 11212-1. Any queries relating to the EN should be directed to BSI, quoting the reference AW/100. Cross-references The British Standards which implement international or European publications referred to in this document may be found in the BSI Standards Cata
5、logue under the section entitled “International Standards Correspondence Index”, or using the “Find” facility of the BSI Standards Electronic Catalogue. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their cor
6、rect application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This document comprises a front cover, an inside front cover, pages i and ii, theEN ISO title page, page 2, the ISO title page, page ii, pages 1 to 4 and a back cover. Thi
7、s standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cover. Amendments issued since publication Amd. No. Date CommentsBSENISO11212-1:1997 BSI 01-1999 i Contents Page National foreword Inside front
8、 cover Foreword 2 Foreword ii Text of ENISO11212-1 1ii blankEUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN ISO 11212-1 March 1997 ICS 67.180 Descriptors: See ISO document English version Starch and derived products Heavy metals content Part 1: Determination of arsenic content by atomic absorpt
9、ion spectrometry (ISO 11212-1:1997) Amidons, fcules et produits drivsTeneur en mtaux lourdsPartie 1: Dtermination de la teneur en arsenic par spectromtrie dabsorption atomique (ISO 11212-1:1997) Strke und Strkederivate SchwermetallgehaltTeil 1: Bestimmung des Arsengehaltes durch Atomabsorptionsspekt
10、rometrie (ISO 11212-1:1997) This European Standard was approved by CEN on 1997-02-28. 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
11、and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CEN member. The European Standards exist in three official versions (English, French, German). A version in any other language made by translation under the responsib
12、ility of a CEN member into its own language and notified to the Central Secretariat has the same status as the official versions. CEN members are the national standards bodies of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Po
13、rtugal, Spain, Sweden, Switzerland and United Kingdom. CEN European Committee for Standardization Comit Europen de Normalisation Europisches Komitee fr Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels 1997 CEN All rights of exploitation in any form and by any means reserved worldwide
14、 for CEN national Members. Ref. No. EN ISO 11212-1:1997 EENISO11212-1:1997 BSI 01-1999 2 Foreword The text of the International Standard ISO11212-1:1997 has been prepared by Technical Committee ISO/TC 93 “Starch (including derivatives and by-products)” in collaboration with CEN/CS. This European Sta
15、ndard shall be given the status of a national standard, either by publication of an identical text or by endorsement, at the latest by September 1997, and conflicting national standards shall be withdrawn at the latest by September 1997. According to the CEN/CENELEC Internal Regulations, the nationa
16、l standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and the United Kingdom. Endorsement notice T
17、he text of the International Standard ISO11212-1:1997 was approved by CEN as a European Standard without any modification. Contents Page 1 Scope 1 2 Definition 1 3 Principle 1 4 Reagents 1 5 Apparatus 1 6 Procedure 2 7 Expression of results 3 8 Precision 3 9 Test report 3 Annex A (informative) Resul
18、ts of interlaboratory test 4 Figure 1 Digestion apparatus 2 Table A.1 Interlaboratory test on corn starch 4EN ISO 11212-1:1997 ii Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing Intern
19、ational Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with
20、 ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an
21、International Standard requires approval by at least 75% of the member bodies casting a vote. International Standard ISO 11212-1 was prepared by Technical Committee ISO/TC 93, Starch (including derivatives and by-products). ISO 11212 consists of the following parts, under the general title Starch an
22、d derived products Heavy metals content: Part 1: Determination of arsenic content by atomic absorption spectrometry; Part 2: Determination of mercury content by atomic absorption spectrometry; Part 3: Determination of lead content by atomic absorption spectrometry with electrothermal atomization; Pa
23、rt 4: Determination of cadmium content by atomic absorption spectrometry with electrothermal atomization. Annex A of this part of ISO 11212 is for information only. Descriptors: Starches, food starch, chemical analysis, determination of content, heavy metals, arsenic, atomic absorption spectrometric
24、 method.ENISO 11212-1:1997 BSI 01-1999 1 1 Scope This part of ISO 11212 specifies a method for the determination of the arsenic content of starch, including derivatives and by-products, by atomic absorption spectrometry with hybride generation. The hybride generators currently available use very dif
25、ferent techniques; it is thus impossible to propose a comprehensive method likely to ensure the attainment of satisfactory results on all types of apparatus. Each analyst should therefore optimize the conditions of use of his/her own apparatus on the basis of general or particular instructions. 2 De
26、finition For the purposes of this part of ISO 11212, the following definition applies. 2.1 arsenic content quantity of arsenic determined in accordance with the conditions specified in this method and expressed as arsenic (As), in micrograms per kilogram of the product as received 3 Principle Wet di
27、gestion of the organic matrix. Reduction of arsenic (As 3+ ) to arsenic hydride by hydrogen resulting from the action of sodium borohydride on hydrochloric acid. Entrainment of the hydride form by a flow of gas and determination by atomic absorption spectrometry in a heated quartz cell. Measurement
28、of the absorbance at a wavelength of193,7 nm. Determination of the concentration of arsenic in the sample by means of a calibration curve. 4 Reagents Use only reagents of recognized analytical grade and distilled water or water of equivalent purity. 4.1 Nitric acid (r 20= 1,38 g/ml). 4.2 Hydrogen pe
29、roxide, 30% (V/V) solution. 4.3 Sodium borohydride solution Prepare a solution at the concentration recommended in the instructions for use of the hydride generator (5.3). 4.4 Hydrochloric acid solution Prepare a solution at the concentration recommended in the instructions for use of the hydride ge
30、nerator (5.3). 4.5 Arsenic standard solution, 1 g/l Standard solutions are commercially available at this concentration. These solutions may be prepared by weighing and dissolving the salt or metal of known purity. 4.6 Calibration solutions Before each series of measurements, prepare from the standa
31、rd arsenic solution (4.5) at least five calibration solutions covering the range of concentrations to be determined. 100 ml of each calibration solution shall contain 7,5 ml of nitric acid (4.1). 5 Apparatus All the glassware used shall be previously washed by means of suitable products (such as nit
32、ric acid) and rinsed with distilled water to eliminate any trace of arsenic. Use ordinary laboratory apparatus and, in particular, the following. 5.1 Digestion apparatus (see Figure 1), made of borosilicate glass and consisting of three elements terminating with conical ground joints (5.1.1 to 5.1.3
33、). 5.1.1 Soxhlet extraction tube, of capacity 200ml, equipped with a stopcock and a lateral tube connected directly to the flask (5.1.3). 5.1.2 Cooling apparatus, 35 cm long, connected to the top of the Soxhlet extraction tube (5.1.1). 5.1.3 Round-bottom flask, of capacity 250 ml, connected to the l
34、ower part of the Soxhlet extraction tube (5.1.1). When the stopcock is open, the device is under reflux; when it is closed, the Soxhlet extraction tube(5.1.1) retains the condensed water and acid vapours. 5.2 Atomic absorption spectrometer, consisting of five elements (5.2.1 to 5.2.5). 5.2.1 High-re
35、solution monochromator, allowing a 0,2 nm bandwidth slit. 5.2.2 Correcting device for non-specific absorption. 5.2.3 Measuring and photoelectric reception device, with a response time not exceeding about 10 ms. 5.2.4 Detector and signal processing system, allowing recording of the maximum and/or int
36、egrated absorbance signal.ENISO 11212-1:1997 2 BSI 01-1999 5.2.5 Arsenic discharge lamp or arsenic hollow cathode lamp 5.3 Hydride generator, allowing the generation of hydrides as well as their transport to a heated measuring cell whose wavelength is adapted to the spectrometer, and equipped with a
37、n automatic sampling device which is necessary to obtain good repeatability and to reduce the risk of contamination. 5.4 Pipettes and micropipettes, of suitable capacity. 5.5 Analytical balance 6 Procedure 6.1 Preparation of test sample Thoroughly homogenize the sample. 6.2 Digestion Use the digesti
38、on apparatus described in 5.1. Weigh, to the nearest 1 mg, about 5 g of the test sample into the flask (5.1.3). Add 27,5 ml of nitric acid (4.1) and 1 ml of hydrogen peroxide (4.2). Distil under reflux for 4 h leaving the stopcock open. Turn the stopcock off, continue heating and distil until about
39、20 ml 1 ml of liquid are recovered in the extraction tube (5.1.1). Stop heating and allow the flask to cool. Separate the flask from the extraction tube. Add 20 ml of water to the digested residue in the flask, bring to the boil for a few minutes, stop heating and allow to cool. Transfer the solutio
40、n to a 100 ml volumetric flask, dilute to the mark with distilled water and stir. 6.3 Blank test Perform digestion under the same conditions as in 6.2, replacing the test portion by 5 ml of water. 6.4 Determination of the calibration curve Carry out the analysis of the diluted calibration solutions
41、(4.6) with reference to the instructions for use of the hydride generator (5.3), by adding the recommended quantities of hydrochloric acid solution (4.4) and sodium borohydride solution (4.3). Measure the absorbance of each calibration solution at a wavelength of 193,7 nm using the spectrometer (5.2
42、). Draw the calibration curve by plotting the arsenic concentrations of the calibration solutions, expressed in micrograms per litre, as the abscissa against the corresponding values of the signal, read either in maximum absorbance or in integrated absorbance, as the ordinate. The calibration curve
43、shall be periodically checked depending on the length of the series of analyses. 6.5 Determination Measure the absorbance of the test samples under the same conditions as the calibration solutions and compare the results with the previously plotted calibration curve. Figure 1 Digestion apparatusENIS
44、O 11212-1:1997 BSI 01-1999 3 7 Expression of results With reference to the calibration curve, determine the concentrations corresponding to the signals of the test portion and the blank. The arsenic concentration of the sample, w, expressed in micrograms per kilogram of the product as received, is g
45、iven by the equation: where NOTEWhen strictly following this method, the quantification limit can reach 20 g/kg. 8 Precision Details of an interlaboratory test on the precision of the method are summarized in Annex A. The values derived from the interlaboratory test may not be applicable to analyte
46、concentration ranges and matrices other than those given in Annex A. 8.1 Repeatability The absolute difference between two independent single test results, obtained using the same method on identical test material in the same laboratory by the same operator using the same equipment within a short in
47、terval of time, will not exceed the repeatability limit r deduced from Table A.1 in more than 5% of cases. 8.2 Reproducibility The absolute difference between two single test results, obtained using the same method on identical test material in different laboratories with different operators using d
48、ifferent equipment, will not exceed the reproducibility value R deduced from Table A.1 in more than 5% of cases. 9 Test report The test report shall specify: the method in accordance with which sampling was carried out, if known; the method used; the test result(s) obtained; and if the repeatability
49、 has been checked, the final quoted result obtained. It shall also mention all operating details not specified in this part of ISO11212, or regarded as optional, together with details of any incidents which may have influenced the test result(s). The test report shall include all information necessary for the complete identification of the sample. r 1 is the numerical value of the arsenic concentration, in micrograms per litre, of the test solution (6.2) read from the calibration curve (6.4); r 0 is the numerical value of
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