1、| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | BRITISH STANDARD BS EN 12396-2:1999 The Eu
2、ropean Standard EN 12396-2:1998 has the status of a British Standard ICS 67.050 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAW Non-fatty foods Determination of dithiocarbamate and thiuram disulfide residues Part 2: Gas chromatographic methodBS EN 12396-2:1999 This British Sta
3、ndard, having been prepared under the direction of the Consumer Products and Services Sector Committee, was published under the authority of the Standards Committee and comes into effect on 15 March 1999 BSI 03-1999 ISBN 0 580 30691 7 Amendments issued since publication Amd. No. Date Text affected N
4、ational foreword This British Standard is the English language version of EN 12396-2:1998. The UK participation in its preparation was entrusted to Technical Panel AW/-/3, Food analysis Horizontal methods, which has the responsibility to: aid enquirers to understand the text; present to the responsi
5、ble European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor related international and European developments and promulgate them in the UK. A list of organizations represented on this panel can be obtained on request to its secretar
6、y. Cross-references The British Standards which implement international or European publications referred to in this document may be found in the BSI Standards Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Find” facility of the BSI Standards El
7、ectronic Catalogue. A British Standard does not purport to include all the necessary provisions of a contract. Users of British Standards are responsible for their correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pages This
8、 document comprises a front cover, an inside front cover, the EN title page, pages 2 to 7 and a back cover.CEN European Committee for Standardization Comite Europe en de Normalisation Europa isches Komitee fu r Normung Central Secretariat: rue de Stassart 36, B-1050 Brussels 1998 CEN All rights of e
9、xploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 12396-2:1998 E EUROPEAN STANDARD EN 12396-2 NORME EUROPE ENNE EUROPA ISCHE NORM October 1998 ICS 67.040 Descriptors: food products, chemical analysis, determination of content, pesticides, fungicides, p
10、esticide residues, chromatographic analysis, gas chromatography English version Non-fatty foods Determination of dithiocarbamate and thiuram disulfide residues Part 2: Gas chromatographic method Aliments non gras De termination des re sidus de dithiocarbamates et de bisulfures de thiurame Partie 2:
11、Me thode par chromatographie en phase gazeuse Fettarme Lebensmittel Bestimmung von Dithiocarbamat- und Thiuramdisulfid-Ru cksta nden Teil 2: Gaschromatographisches Verfahren This European Standard was approved by CEN on 2 October 1998. CEN members are bound to comply with the CEN/CENELEC Internal Re
12、gulations 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 Central Secretariat or to any CEN member. This
13、 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 Central Secretariat has the same status as the official versions. CEN members are the
14、 national standards bodies of Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.Page 2 EN 12396-2:1998 BSI 03-1999 Foreword This European Standard has been pre
15、pared 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 an identical text or by endorsement, at the latest by April 1999, and conflicting nati
16、onal standards shall be withdrawn at the latest by April 1999. This European Standard EN 12396, Non-fatty foods Determination of dithiocarbamate and thiuram disulfide residues, consists of three parts: Part 1: Spectrometric method; Part 2: Gas chromatographic method; Part 3: Xanthogenate method. Acc
17、ording to the CEN/CENELEC Internal Regulations, the national standards organizations of the following countries are bound to implement this European Standard: Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Netherlands, Norway, Portug
18、al, Spain, Sweden, Switzerland and the United Kingdom. Contents Page Foreword 2 1 Scope 3 2 Normative references 3 3 Principle 3 4 Reagents 3 5 Apparatus 4 6 Sampling 4 7 Preparation of the samples 4 8 Procedure 4 9 Expression of the results 5 10 Confirmatory tests 5 11 Precision 5 12 Test report 5
19、Annex A (informative) Precision 6 Annex B (informative) Gas chromatographic operating conditions 6 Annex C (informative) Bibliography 7Page 3 EN 12396-2:1998 BSI 03-1999 1) r is the mass concentration. 1 Scope This European Standard specifies a gas chromatographic method for the determination of res
20、idues of dithiocarbamates and thiuram disulfides, which release carbon disulfide under the described conditions (e.g. mancozeb, maneb, propineb, thiuram, zineb). It is applicable to such compounds in and on fruits and some vegetables but also in and on cereals and other foodstuffs of plant origin. O
21、nly the quantification of the whole group is possible using this method, not the identification of individual compounds. Generally the maximum residue limits (MRLs) are expressed in terms of carbon disulfide. 2 Normative references This European Standard incorporates, by dated and undated reference,
22、 provisions from other publications. These normative references are cited at the appropriate places in the text and the publications are listed hereafter. For dated references, subsequent amendments to or revisions of any of these publications apply to this European Standard only when incorporated i
23、n it by amendment or revision. For undated references the latest edition of the publication referred to applies. EN 12393-1:1998, Non-fatty foods Multiresidue methods for the gas chromatographic determination of pesticide residues Part 1: General considerations. EN 12393-3, Non-fatty foods Mutiresid
24、ue methods for the gas chromatographic determination of pesticide residues Part 3: Determination and confirmatory tests. EN 12396-1, Non-fatty foods Determination of dithiocarbamate and thiuram disulfide residues Part 1: Spectrometric method. ISO 1750, Pesticides and other agrochemicals Common names
25、. 3 Principle The sample is heated with hydrochloric acid and tin(II)chloride in a gas-tight flask to release carbon disulfide from any dithiocarbamates and/or thiuram disulfide present. The quantity of carbon disulfide collecting in the headspace of the flask is determined by gas chromatography (GC
26、) with an electron capture detector (ECD) or with a flame-photometric detector (FPD) in the sulfur mode. For further information on the principle of this method, see 1 to 4. 4 Reagents 4.1 General Unless otherwise stated, use reagents of recognized analytical grade, preferably for pesticide residue
27、analysis, and only distilled or demineralized water. Label all standard containers with name and purity of all pesticides. For the full chemical names and structures, see ISO 1750. Take every precaution to avoid possible contamination of water, solvents, inorganic salts etc. by plastics and rubber m
28、aterials or even by air. Use only glass containers for storage and handling of all water and reagents. 4.2 Acetone. 4.3 Light petroleum, boiling range 408Ct o6 08 C. 4.4 Carbon disulfide, colourless, at least 99 % of mass concentration. If stored at2208C it is stable for 2 years to 3 years. 4.5 Hydr
29、ochloric acid, concentrated, r 20 (HCl) = 1,16 g/ml. 4.6 Tin(II)chloride - hydrochloric acid solution, r(SnCl 2 2H 2 O) = 15 g/l 1) . Dissolve 15 g of tin(II)chloride dihydrate in 400 ml of concentrated hydrochloric acid (4.5) and dilute to 1 000 ml with water. 4.7 Carbon disulfide stock solution, r
30、(CS 2 ) 25 mg/ml. Weigh to the nearest 10 mg a stoppered 50 ml volumetric flask with ground glass neck containing 40 ml of acetone (4.2) or light petroleum (4.3). Pipette into this about 1 ml of carbon disulfide (4.4) (according to about 1,25 g), close the flask immediately and weigh again to the ne
31、arest 10 mg in order to determine the exact mass of carbon disulfide taken. Dilute to the mark with light petroleum or acetone and mix well. Prepare freshly for each calibration curve. 4.8 Carbon disulfide standard solutions 4.8.1 Carbon disulfide standard solution I, r(CS 2 ) 10 mg/ml. Pipette 20 m
32、l of carbon disulfide stock solution (4.7) into a 50 ml volumetric flask and dilute to the mark with light petroleum (4.3) or acetone (4.2)a s appropriate. Prepare freshly for each calibration curve. 4.8.2 Carbon disulfide standard solution II, r(CS 2 ) 1 mg/ml. Pipette 5 ml of carbon disulfide stan
33、dard solution I (4.8.1) into a 50 ml volumetric flask and dilute to the mark with light petroleum (4.3)o r acetone (4.2), as appropriate. Prepare freshly for each calibration curve.Page 4 EN 12396-2:1998 BSI 03-1999 5 Apparatus 5.1 General Thoroughly clean glassware shall be used. See EN 12393-1:199
34、8, 5.1 for the cleaning of glassware. Usual laboratory equipment and, in particular, the following. 5.2 Digestion flask, 250 ml glass bottle with a screw cap which has been drilled with a 3 mm hole and fitted with a polytetrafluoroethylene (PTFE) septum. 5.3 Water bath, capable of being controlled a
35、t approximately 708C. 5.4 Gas-tight injection syringes, 100ml and 1 000ml. Check the gas-tightness of the syringes regularly. 5.5 Gas chromatograph, equipped with an electron capture detector (ECD) or a flame-photometric detector (FPD) in the sulfur mode (filter 394 nm). A suitable GC system, prefer
36、ably equipped with separate heaters for injector, detector and column oven, should be used. See annex B. Variation in the detector sensitivity should be checked periodically by verifying the calibration curve using carbon disulfide standard solutions. For the determination of carbon disulfide, packe
37、d glass columns are mostly used. For stationary phases and support materials see EN 12393-3. 6 Sampling Prepare the laboratory sample according to a generally recommended method of sampling to achieve a representative part of the product to be analysed. NOTE Sampling procedures for the official cont
38、rol of pesticide residues in and on fruits and vegetables are given in EEC directive 79/700/EEC 5. 7 Preparation of the samples 7.1 Test sample If the sample reaches the laboratory frozen, store it at 2208C before analysis. Where possible, carry out the analysis of fresh samples immediately after th
39、eir arrival in the laboratory. Do not analyse a laboratory sample which is wholly or extensively spoiled. For analysis take only the portion of the laboratory sample to which the maximum residue limit applies. No further plant-parts may be removed. A record of the plant-parts which have been removed
40、 shall be kept. The sample thus prepared is the analytical sample. If the sample cannot be analysed immediately, store it at 08Ct o58 C for no longer than 2 days before analysis. The reduction of the analytical sample shall be carried out in such a way that representative portions are obtained (e.g.
41、 by division into four and selection of opposite quadrants). When the samples are in small units (e.g. small fruits, vegetables, cereals), the analytical sample shall be thoroughly mixed before weighing out the test portion. When the samples are in larger units, take wedge-shaped sections (e.g. larg
42、e fruits and vegetables) or cross-sections (e.g. cucumbers) which include the outer surface from each unit. NOTE The residues of dithiocarbamate and thiuram disulfide, which are on the surface of the plant-parts and are not systemic, decompose rapidly, especially in chopped samples. Therefore precau
43、tions should be taken to avoid decomposition. If samples have to be stored for more than 2 days, they shall be deep-frozen at2208C. To ensure that even after thawing representative samples can be taken, prepare portions of the product which are each sufficient for one analysis. 7.2 Test portion Weig
44、h out test portions of masses up to 200 g to an accuracy of 1 %. After weighing out the test portion, remove any parts which would interfere with the analytical procedure. In the case of stone fruits, the stones are removed after weighing out. The basis for the calculation of the residue mass fracti
45、on is the mass of the original test portion (with stones). The test portion shall not be cut or reduced to smaller pieces than can just pass the neck of the reaction flask, as the residues of dithiocarbamate and thiuram disulfide fungicides fall the more the test portion is cut. Analyse the test por
46、tion immediately after cutting. 8 Procedure 8.1 Safety aspects WARNING: Many dithiocarbamates, thiuram disulfides and carbon disulfide are toxic by various routes of exposure, especially in concentrated form. When working with dithiocarbamates, thiuram disulfides and carbon disulfide, consult safety
47、 data sheets of the manufacturer for information. Vapours from some volatile solvents are toxic. Several of these solvents can easily be absorbed through skin. Use effective fume hoods to remove vapours of these solvents as they are set free. 8.2 Preparation of blanks Prepare reagent and commodity b
48、lanks. Spiked recovery tests at levels appropriate to the maximum residue limits should be carried out as specified in annex A and shall lead to satisfactory results. Test the purity of the reagents and solvents by performing reagent blanks. Test solvents by gas chromatography to determine whether t
49、hey are free from any interfering impurity whose concentration is at the limit of determination. Ensure that the laboratory is free from atmospheric contamination that would give a background response for carbon disulfide, by injecting a few hundred microlitres of air into the GC column. The chromatograph shall not show any interfering impurity. NOTE 1 Analysts should thoroughly familiarize themselves with the method before starting the analyses. NOTE 2 Some vegetables (e.g. those of the family Cruciferae) c
