1、| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | BRITISH STANDARD BS EN 12396-1:1999 The Eu
2、ropean Standard EN 12396-1:1998 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 1: Spectrometric methodBS EN 12396-1:1999 This British Standard,
3、 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 30690 9 Amendments issued since publication Amd. No. Date Text affected Nationa
4、l foreword This British Standard is the English language version of EN 12396-1:1998. 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 responsible in
5、ternational/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
6、secretary. 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 Stan
7、dards 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 correct application. Compliance with a British Standard does not of itself confer immunity from legal obligations. Summary of pa
8、ges This 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.CEN European Committee for Standardization Comite Europe en de Normalisation Europa isches Komitee fu r Normung Central Secretariat: rue de Stassart 36, B-1050 Bru
9、ssels 1998 CEN All rights of exploitation in any form and by any means reserved worldwide for CEN national Members. Ref. No. EN 12396-1:1998 E EUROPEAN STANDARD EN 12396-1 NORME EUROPE ENNE EUROPA ISCHE NORM October 1998 ICS 67.040 Descriptors: food products, chemical analysis, determination of cont
10、ent, pesticides, fungicides, pesticide residues, spectrophotometric analysis English version Non-fatty foods Determination of dithiocarbamate and thiuram disulfide residues Part 1: Spectrometric method Aliments non gras De termination des re sidus de dithiocarbamates et de bisulfures de thiurame Par
11、tie 1: Me thode spectrome trique Fettarme Lebensmittel Bestimmung von Dithiocarbamat- und Thiuramdisulfid- Ru cksta nden Teil 1: Spektralphotometrisches Verfahren This European Standard was approved by CEN on 2 October 1998. CEN members are bound to comply with the CEN/CENELEC Internal Regulations w
12、hich 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 European S
13、tandard 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 national s
14、tandards 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 12396-1:1998 BSI 03-1999 Foreword This European Standard has been prepared by Te
15、chnical 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 national standa
16、rds 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. According to t
17、he 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, Portugal, Spain,
18、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 5 7 Preparation of the samples 5 8 Procedure 5 9 Expression of the results 6 10 Confirmatory tests 6 11 Precision 7 12 Test report 7 Annex A (in
19、formative) Precision data 8 Annex B (informative) Bibliography 8Page 3 EN 12396-1:1998 BSI 03-1999 1) r is the mass concentration. 1 Scope This European Standard specifies a spectrometric method for the determination of residues of dithiocarbamates and thiuram disulfides, which release carbon disulf
20、ide under the described conditions (e.g. mancozeb, maneb, propineb, thiuram, zineb). It is applicable to such compounds in and on fruits and many vegetables and also in and on cereals and other foodstuffs of plant origin. Only the quantification of the whole group is possible using this method but n
21、ot 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 or undated reference, provisions from other publications. These normative references are cited at
22、 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 in it by amendment or revision. For undated references the latest edition of
23、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 12396-2, Non-fatty foods Determination of dithiocarbamate and thiuram disulfide residues Part 2: Gas chromatog
24、raphic method. ISO 1750, Pesticides and other agrochemicals Common names. 3 Principle The sample is heated with hydrochloric acid and tin(II)chloride to release carbon disulfide from any dithiocarbamates and/or thiuram disulfide present. The carbon disulfide is separated and purified by distillation
25、 and collected in an ethanolic solution of copper(II)acetate and diethanolamine. With copper(II)acetate and diethanolamine, the carbon disulfide forms two yellow copper(II)-N,N-bis(2-hydroxy-ethyl)-dithiocarbamate complexes with the molar ratio Cu:CS 2 = 1:1 and 1:2. The absorption of these reaction
26、 products is measured in a spectrometer at a wavelength of 435 nm and the concentration of dithiocarbamate and/or thiuram disulfide residues is calculated and expressed in terms of milligrams (mg) of carbon disulfide per kilogram (kg) of foodstuff. For further information on the principle of this me
27、thod, see 1 to 4. 4 Reagents 4.1 General Unless otherwise stated, use reagents of recognized analytical grade, preferably for pesticide residue analysis, and only distilled or demineralized water. Label all standard containers with name and purity of all pesticides. For the full chemical names and s
28、tructures, see ISO 1750. Take every precaution to avoid possible contamination of water, solvents, inorganic salts etc. by plastics and rubber materials. Use only glass containers for storage and handling of all water and reagents. 4.2 Carbon disulfide, colourless, mass concentration of at least 99
29、%. If stored at2208C it is stable for 2 years to 3 years. 4.3 Diethanolamine, at least 99 % of mass concentration. 4.4 Ethanol, mass concentration of at least 95 %. 4.5 Hydrochloric acid, concentrated, r 20 (HCl) = 1,16 g/ml. 4.6 Sulfuric acid (optional), concentrated, r 20 (H 2 SO 4 ) = 1,84 g/ml 4
30、.7 Sodium hydroxide solution, r(NaOH) = 100 g/l 1) . 4.8 Copper(II)acetate solution, r(Cu(CH 3 COO) 2 H 2 O) = 400 mg/l. Weigh 400 mg of copper(II)acetate monohydrate, to the nearest 1 mg, with gentle warming only, in 250 ml of ethanol (4.4). Dilute 25 ml of this solution to 100 ml with ethanol. 4.9
31、 Lead acetate solution (optional), r(Pb(CH 3 COO) 2 3H 2 O) = 300 g/l. 4.10 Tin(II)chloride solution, r(SnCl 2 2H 2 O) = 40 g/100 ml in concentrated hydrochloric acid (4.5). 4.11 Tin(II)chloride - hydrochloric acid solution, r(SnCl 2 2H 2 O) = 3,3 g/100 ml. Mix 20 ml of tin(II)chloride solution (4.1
32、0) with 20 ml of concentrated hydrochloric acid (4.5) and add carefully 200 ml of water. 4.12 Zinc acetate solution (optional), r(Zn(CH 3 COO) 2 ) = 20 g/100 ml. 4.13 Carbon disulfide stock solution Weigh to the nearest 10 mg a stoppered 50 ml volumetric flask with a ground glass neck containing 40
33、ml of ethanol (4.4). Add approximately 1 ml of carbon disulfide (4.2) (equivalent to approximately 1,25 g) using a pipette, close the flask at once and re-weigh to the nearest 10 mg to obtain the exact mass of carbon disulfide by difference. Dilute to the mark with ethanol and mix well. Prepare fres
34、hly for each calibration curve.Page 4 EN 12396-1:1998 BSI 03-1999 1 Liebig condenser 4 cylindrical flask or round bottomed flask 2 dropping funnel 5 absorption tubes 3 gas inlet tube 6 Widmer helix Figure 1 Decomposition and distillation apparatus 4.14 Carbon disulfide standard solution Pipette 5 ml
35、 of carbon disulfide stock solution (4.13) into a 50 ml volumetric flask and dilute to the mark with ethanol (4.4). Pipette 5 ml of this dilution into a 250 ml volumetric flask and dilute to the mark with ethanol. 1 ml of this standard solution is equivalent to approximately 50mg of carbon disulfide
36、. Prepare freshly for each calibration curve. 4.15 Colour reagent Successively introduce 100 ml of ethanol (4.4), 30 ml of copper(II)acetate solution (4.8) and 25 g of diethanolamine (4.3) into a 250 ml volumetric flask, and dilute to the mark with ethanol. 5 Apparatus 5.1 General Thoroughly clean g
37、lassware shall be used. See EN 12393-1:1998, 5.1 for the cleaning of glassware. Usual laboratory equipment and, in particular, the following. 5.2 Decomposition and distillation apparatus, consisting of a 1 l or 2 l round bottomed three necked flask or cylindrical flask with a three necked adapter, a
38、 dropping funnel, a gas inlet tube, an ascending Liebig condenser, three absorption tubes, the last two preferably fitted with a Widmer helix, connected by spherical socket joints, the first being attached to the Liebig condenser (see Figure 1).Page 5 EN 12396-1:1998 BSI 03-1999 5.3 Flowmeter. 5.4 H
39、eating mantle, electrically operated, at least 450 W; or gas burner fitted with a Babo funnel and flask holder 5.5 Spectrometer, suitable for measurements at a wavelength of 435 nm, with a 1 cm glass or quartz cell. A double beam spectrometer should preferably be used. 5.6 Water jet pump, attached t
40、o the last absorption tube, or a source of nitrogen under pressure, attached to the gas inlet tube. 6 Sampling Prepare the laboratory sample according to generally recommended methods of sampling to achieve a representative part of the product to be analysed. NOTE Sampling procedures for the officia
41、l control 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 af
42、ter their 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 r
43、emoved shall be kept. The sample thus prepared is the analytical sample. If the sample cannot be analysed immediately, it may be stored 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
44、obtained (e.g. 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 secti
45、ons (e.g. large 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. The
46、refore precautions 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
47、 portion Weigh 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 residu
48、e mass fraction 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 fall the more the test portion is cut. Analyse the test p
49、ortion immediately after cutting. 8 Procedure 8.1 Safety aspects WARNING: Many dithiocarbamates, thiuram disulfides, and carbon disulfides are toxic by various routes of exposure, especially in concentrated form. When working with dithiocarbamates, thiuram disulfides and carbon disulfides, consult safety data sheets of the manufacturer for information. Vapours from some volatile solvents are toxic. Several of these solvents can easily be absorbed through the skin. Use effective fume hoods to remove vapours of
