1、STD*CEN EN 3239h-Z-ENGL 3998 O 3L104589 0380928 540 RATIFIED EUROPEAN TEXT EN12396-2:1998 European Standards only exist formally as national transpositions (.e. a BS EN for the UK) of a commonly agreed “ratified“ text. This document is a ratified text which will shortly be published as a BS EN. It i
2、s being made available in advance of its formal publication to give interested parties early access to the technical information which the BS EN will contain. When the BS EN is formally published it will be supplied to you automatically, without any additional charge. Purchasers of this ratified tex
3、t should be aware of the following limitations when using the document. O The BS EN may contain additionai information in the national foreword or national annex, O Full rights conferred by compliance with the standard may only be granted by reference to the formal national transposition of the text
4、 as a BS EN. This ratified text was approved by CENICENELEC in its three official languages on the date given below. Under CENKENELEC rules, BSI is obliged to publish its national transposition within six months of this date. This ratified text was approved on 1998-10-02 NO COPYING WITHOUT BSI PERMI
5、SSION EXCEPT AS PERMITTED BY COPYRIGHT LAW STDeCEN EN L237b-2-ENGL 3778 m 3404507 0380727 487 m EUROPEAN STANDARD NORME EUROPENNE EURWISCHE NORM October 1998 ICC 67.040 Descriptors: food products, chemical analysis, determination of content, pesticides, fungicides, pesticide residues, chromatographi
6、c analysis, gas chromatography English version Non-fatty foods - Determination of dithiocarbamate and thiuram disulfide residues - Part 2: Gas chromatographic method Aliments non gras - termination des rsiidus de dithiocarbamates et de bisulfures de thiurame - Partie 2: Mdthode par chromatographie e
7、n phase gazeuse Fettarme Lebensmittel - Bestimmung von Diaiiocarbamat- und iuradwM-R 0,l mgkg; 0,2 mg/kg; 0,4 mgkg; 0,8 mgkg; 1,2 mgkg; 1,6 mg/kg and 2,0 mgkg of residue as carbon disulfide in a 50 g sample. Place the spiked digestion flasks in the water bath (5.3) for 2 h and follow the procedure d
8、escribed in 8.5.2. Plot a calibration curve from the peak areas or peak heights against amounts of carbon disulfide added. NOTE: As the response from the flame photometric detector follows a square function, the chart recoder readings should be plotted as logarithmic to give linearity. 8.5 Sample me
9、asurement 8.5.1 Preparation of the digestion flask Introduce a 50 g test portion into the digestion flask (5.2), add 100 ml of tin(ll)chloride-hydrochloric acid solution (4.6) and immediately close the flask tightly with the PTFE septum and screw cap. Place the flask into the thermostatically contro
10、lled water bath (5.3) for 2 h. Shake vigorously the flask for 2 min at least 3 times during the digestion stage, in order to fully release carbon disuifide from any dithiocarbamate and thiuram disulfide present. Remove the flask and allow to cool to room temperature. STD-CEN EN 1239b-Z-ENGL 1798 = 3
11、404589 018093b bL7 Page 8 EN 12396-21998 8.5.2 Gas chromatographic measurement Inject 25 pl to 300 pI of the cooled headspace gas from the digestion flask at room temperature into the gas chromatograph (5.5). Injections of the sample shall be preceded and followed by injection of the headspace gas a
12、bove one of the standard solutions obtained in 8.4. 9 Expression of the results Read off the amount of carbon disulfide present in the sample from the calibration cuwe. Calculate the mass fraction of residue w, in milligrams per kilogram, expressed in terms of carbon disulfide using equation (1): wh
13、ere: m, is the mass of carbon disulfide released (read off from the calibration curve), in micrograms; tq is the mass of the test portion (before the removal of any parts for example stones), in grams. If the results indicate that the amount of residue approaches or exceeds the maximum residue limit
14、, at least two further test portions shall be examined. NOTE: The routine limit of determination depends on the amount of test portion used. If the mass of the test portion is 50 g, the routine limit of determination lies at approximateiy O,OI mgiicg. 10 Confirmatory tests Analyses for confirmation
15、using a different method should be performed, especially in those cases in which the result indicates that the maximum residue limit has been exceeded. NOTE 1: The method in EN 12396-1 permits carbon disulfide to be determined spectrometrically. NOTE 2: The method in EN 12396-3 permits carbon disulf
16、ide to be determined spectrometrically as xanthogenate and is especially useful for the determination of low levels of dithiocarbamate and thiuramdisuifide residues. NOTE 3: Coupled gas chromatography-mass spectrometry (GC-MS) is a specific method to confirm the identity and the quantity of carbon d
17、isulfide in samples prepared according to 8.5.1. NOTE 4: A method which determines undestroyed ethylene and propylene bis-dithiocarbamates as their respective sodium salts by means of gel chromatographic separation and on line photometric determination at a wavelength of 285 nm is described in 6. -
18、- STD-CEN EN 1239b-Z-ENGL 1998 I3404587 0180937 553 Page 9 EN 12396-2: 1 998 11 Precision Some general criteria, based on experience, are given in annex A as guidance for the analyst. 12 Testreport The test report shall contain at least the following information: - all information necessary for the
19、identification of the sample; - a reference to this European Standard; - the results and the units in which they have been expressed; - date and type of sampling procedure (if known); - date of receipt of sample in the laboratory; - date of test; - any particular points observed in the course of the
20、 test; - any operations not specified in the method or regarded as optional which might have affected the results. Page 10 EN 1 2396-2: 1 998 Residue level mg/kg 0,Ol o 0,100 1,000 Annex A (informative) Difference (I) msns 0,005 0,025 0,125 Precision Residue level msng 0,Ol 0,lO 1 ,o0 A.1 General Di
21、fference (I) mmg 0,Ol 0,05 0,25 The precision of the analytical method should be evaluated in accordance with the requirements of IS0 57231 986 7. A.2 Repeatability conditions Repeatability conditions are defined as conditions under which mutually independent test resuits are obtained with the same
22、method on identical test material in the same laboratory by the same operator using the same equipment within short intervals of time. Each laboratory should periodically determine if its results under repeatability conditions are acceptable by analysing samples which have been spiked with appropria
23、te pesticides or preferably by using samples with incurred residues, at concentrations, if possible near to the maximum residue limits. Table A.l shows examples of acceptable differences of test results obtained under repeatability conditions. Table A.l: Examples of acceptable differences of test re
24、sults obtained under repeatability conditions In this example, 0,Ol mgkg is near the limit of determination. Determine intermediate values by interpolation from a log-log graph. A.3 Reproducibility conditions Reproducibility conditions are defined as those conditions under which test results are obt
25、ained with this method on identical test material in different laboratories with different operators using different equipment. Table A.2 shows acceptable differences of test results obtained under reproducibility conditions. Table A.2: Examples of acceptable differences of test results obtained und
26、er reproducibility conditions , Page 11 EN 12396-2: 1 998 In this example, 0,Ol mgkg is near the limit of determination. Determine intermediate values by interpolation from a log-log graph. A.4 Recovery The laboratory performance should be assessed periodically by cartying out recovery studies to es
27、tablish the recovery level of pesticide residues. This should be done by analysing samples which have been spiked with ethanolic solutions of nabam or thiram, at concentrations near to the maximum residue limit and at 111 O* of it. These samples should be of the same type as those examined for resid
28、ue content. The mean of recoveries from replicate determinations should fall within the range of 70 % up to 110 %, with a relative standard deviation less or equal to 30 %. Annex B (informative) Gas chromatographic operating conditions B.1 The following gas chromatographic operating conditions have
29、been proven to be satisfactory: 6.2 Packed columns Column size Column filling Column temperature Column size Column filling Column temperature Column size Column filling Column temperature Column site Column filling Column temperature Detector Injector temperature 1,20 m x 2 mm Tenax, 190 pm to 250
30、pm (60 mesh to 80 mesh) 100 “C 130 m x 4 mm Porapak Q, 150 pm to 190 pm (80 mesh to 1 O0 mesh) 200 “C 1,80mx4mm 2 % OV 1 on Gas Chrom Q, 150 pm to 190 pm (80 mesh to 1 O0 mesh) 100 “C 1,80 m x 2 mm 3 % OV 1 on Chromosorb AW-DMCS, 150 pm to 190 pm (80 mesh to 100 mesh) 75 “C Electron capture detector
31、, temperature 300 “C About 150 OC Page 12 EN 12396-21998 8.3 Capillary columns Column Fused silica capillary CP-SiI8CB (50 m x 0,32 mm; film thickness 1,2 pm) Column temperature: - isothermal 55 OC for 10 min; - programmed to rise at 15 “C/min from 55 OC to 200 OC; - isothermal at 200 OC for 1 O min
32、. Detect or Electron capture detector, temperature 300 OC Injector temperature About 150 OC Annex C (informative) Bibliography McLeod, H.A., and McCully, C.A.: Head space gas chromatographic procedure for screening food samples for dithiocarbamate pesticide residues, J. Assoc. ff. Anal. Chem, 52, pp
33、.1226-1230, 1969. Panel on determination of dithiocarbamate residues of the Committee for Analytical Methods for Residues of Pesticides and Veterinary Products in Foodstuffs of the Ministry of Agriculture, Fisheries and Food: Determination of residues of dithiocarbamate pesticides in foodstuffs by a
34、 headspace method, Analyst, 106, pp. 782-787, 1981. EEC document: 1729NV80 - final 1. Greve, P.A. (editor): Analytical methods for residues of pesticides in foodstuffs: Part II, Method Dithiocarbamates, 5th edition, SDU publishers, 1988,. Den Hague. EEC Commission directive of 24.7.79 (79/700/EEC) e
35、stablishing community methods of sampling for the official control of pesticide residues in and on fruits and vegetables. Official Journal of the European Communities L 207, 15.8.79. Pflugmacher, J., and Ebing, W.: Ethylene and propylene bisdithiocarbamate fungicides. In: Deutsche Forschungsgesellschaft, Manual of Pesticide Residue Analysis, VCH Verlagsgesellschaft Weinheim 1987, Vol.1, pp.407-412, method S 21. IS0 57231 986 Precision of test methods - Determination of repeatability and reproducibility for a standard test method by inter-laboratory tests.
