1、 - STD-BSI BS EN 13L9L-L-ENGL 2000 Lb24bb9 08b29b7 534 D BRITISH STANDARD BS EN 13191-1:2000 Non-fatty food - Determination of bromide residues - Part 1: Determination of total bromide as inorganic bromide The European Standard EN 13191-1:2OOO has the status of a British Standard ICs 67.050 NO COPYI
2、NG WITHOUT BSI PEBMISSION EXCEPT AS PEBMI“ED BY COPYRIGHT LAW STD.BSI BS EN L3LL-l-ENGL 2000 Lb24bb OBb2b8 400 = BS EN 13191-1:2000 AmdNo. This British Standard, having been prepared under the direction of the Consumer Products and Services Sector Committee, was published under the authority of the
3、Standards Committee and comes into effect on 16 August 2000 Date Comments 0 BSI 082000 1 ISBN 01580 34847 4 National foreword This British Standard is the officiai English language version of EN 13191-1:2000. The UK participation in its preparation was enmted to Technid Committee AW/-/3, Food anaiyi
4、s - Horizontal methods, which has the responsibility to: - aid enquirers to understand the text; - present to the responsible European committee any enquiries on the - monitor related international and European developments and promulgate interpretation, or proposals for change, and keep the UK inte
5、rests informed; them in the UK. A list of organizations represented on this committee can be obtained on request to its secretary. Cross-references The British Standards which implement ink Determination of inorganic bromide. According to the CENICENELEC Internal Regulations, the national standards
6、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, Sweden, Switzerland and the United Kingdom. Annexes A and B
7、are informative. Q BSI 08-2000 Page 3 EN 13191-1:2000 1 Scope This European Standard specifies a gas chromatographic (GC) method for the determination of bromide residues (including some organic bromine present) as inorganic bromide in non-fatty foods. Generally, the maximum residue levels are expre
8、ssed in terms of bromide ion from all sources but not including covalently bound bromine. The method is applicable to beets, carrots, chicory, endives, cereal grains, lettuce, potatoes, spinach, strawberries and tomato. It has been validated in an interlaboratory test on lettuce i. 2 Normative refer
9、ence This draft European Standard incorporates, by dated or undated reference, 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
10、of these publications apply to this draft European Standard only when incorporated in it by amendment or revision. For undated references the latest edition of the publication referred to applies. EN IS0 3696, Water for analytical laboratory use - Specification and test methods (IS0 3696:1987). 3 Pr
11、inciple An aqueous ethanolic extract of the test portion is evaporated to dryness and the residue is ashed in the presence of sodium hydroxide. The ash is solubilized with sulfuric acid and the solution is treated with ethylene oxide in di-isopropyl ether. Inorganic bromide is converted to 2-bromoet
12、hanol, which is analyzed by gas chromatography with electron-capture detection 2. 4 Reagents 4.1 General and safety aspects Unless otherwise specified, use reagents of recognized analytical grade, preferably for pesticide residue analysis, and water of grade 2 according to EN IS0 3696. Take every pr
13、ecaution 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 4.3 4.4 4.5 4.6 4.7 Ethanol, (p(C2H50H) = 96 % (VAI). Sodium hydroxide solution, c(Na0H) = 0,2 mol/l.
14、 Sulfuric acid, c(HZS04) = 0,6 mol/l. Acetone. Di-isopropyl ether, peroxide-free. Before use, check each newly opened bottle by injecting the same volume, e.g. 51.11, into the gas chromatograph as used in 6.3. If interfering peaks are observed, distill over potassium hydroxide. WARNING: Di-isopropyl
15、 ether is extremely flammable. Store protected from light. Unstable peroxides can form upon longer standing or exposure to sunlight in bottles and can result in explosion risk. Work always in a well-ventilated fume hood. Ethylene oxide, rp(C2H40) of at least 993 % volume fraction, in pressurized can
16、 fitted with valve. Store at approximately -20 OC. WARNING: Ethylene oxide is a highly reactive and cancerogenic gas. Work always in a well-ventilated fume hood. Consult the safety data sheets of the manufacturer for information. To destroy excess ethylene oxide solution, add a surplus of sodium chl
17、oride solution, shake several times and allow to stand for some hours. O BSI 08-2000 Page 4 EN 13191-1:2000 4.8 Ethylene oxide solution In a well-ventilated fume hood, pour 96 ml of ice-cold di-isopropyl ether (4.6) into a 100 ml volumetric flask, and add ethylene oxide (4.7) dropwise to the mark fr
18、om the completely inverted, ice-cold pressurized can and mix well. Store at approximately 4 “C. Prepare fresh daily. 4.9 Amrhoniurn sulfate. 4.10 Sodium sulfate, anhydrous. Heat for 5 h at 500 “C. 4.1 I 2-Bromoethanol standard solution, in acetone, p(C,H,BrO) = 1 mgA. 5 Apparatus Usual laboratory ap
19、paratus and, in particular, the following: 5.1 Chopper. 5.2 Homogenizer or high speed blender, fitted with glass jar. 5.3 Centrifuge, provided with glass tubes of capacity I00 ml, and capable of producing a centrifugal acceleration of at least 7 O00 g at the base of the centrifuge tubes. 5.4 Nickel
20、crucibles, e.g. 5,5 cm high, inner diameter 6 cm. 5.5 Water bath, capable of being maintained at 1 O0 OC. 5.6 Laboratory oven, capable of being maintained at approximately 80 OC, with ventilation. 5.7 Muffle furnace, capable of being maintained at approximately 500 OC. 5.8 Conical flask, 250 ml, wit
21、h ground joint. 5.9 Test tubes, 10 ml and 25 ml, with ground joint. 5.10 Gas chromatograph, equipped with an electron-capture detector. 6 Procedure 6.1 Ashing Chop the test sample using the chopper (5.1), avoiding loss of juice. Transfer a test portion of 50 g into the blender cup (5.2) and add 50 m
22、l of water and 50 ml of ethanol (4.2). Blend for 2 min to 3 min and centrifuge at 7 O00 g. Calculate the total volume of supernatant taking into account the water content of the sample. Transfer an aliquot of supernatant corresponding to 15 g of the test portion into a nickel crucible (5.4) and add
23、5 ml of sodium hydroxide solution (4.3). Place the nickel crucible (without lid) on a boiling water bath (5.5) until the liquid is evaporated. Place the nickle crucible first overnight in a well-ventilated oven (5.6) at approximately 80 OC, and then in a muffle furnace (5.7) for 15 min at 500 OC. WA
24、RNING: Good ventilation in the oven is necessary, as otherwise explosions could occur due to the formation of flammable mixtures of ethanol and air. During the ashing procedure, air shall be allowed to come in contact with the evaporated residue, as otherwise mineralization will be incomplete. The c
25、olour of the ash should be grey to dark-grey. NOTE 1 : Sometimes, e.g. in the case of beet samples, the evaporated residue has been found to ignite in the furnace due to inadequate heat transfer. Ignition leads to appreciable losses of bromide. In this case, a smaller test portion should be used. NO
26、TE 2: Reduction of the supernatant corresponding to approximately I g of the test portion is necessary when samples with high content of organic matter are analyzed, because otherwise ashing will be incomplete. 6.2 Derivatization Allow the ash to cool and add 5 ml of sulfuric acid (4.4). Mix the ash
27、 well with the liquid and transfer the content of the crucible to a conical flask (5.8), using 20 ml of acetone (4.5) for rinsing. Add 5 ml of ethylene oxide solution (4.8). Stopper the flask, mix the contents by shaking and allow to stand for 1 h at room temperature. Q BSI 08-2000 STD-BSI BS EN L3L
28、SL-L-ENGL 2000 Lb24669 08b2973 878 Page 5 EN 131 91 -1 12000 Transfer approximately IO ml of the upper organic phase to a 25 ml test tube (5.9) and add 2 g of ammonium sulfate (4.9). Stopper the tube and shake vigorously for 2 min, Allow to settle and transfer approximately 5 ml of the supernatant t
29、o a 10 ml test tube. Add 1 g of sodium sulfate (4.10), stopper the tube, shake well and allow to stand for 30 min at room temperature (sample test solution). 6.3 Gas chromatography Inject equal volumes (B) of the sample test solution derived from 6.2 and of dilutions of 2-bromoethanol standard solut
30、ion (4.11) into the gas chromatograph. Make sure that the gas chromatographic conditions (column length, stationary phase type, injector, detector and column temperatures, gas flow rates, etc.) are such that the separation of 2-bromoethanol from possible interfering peaks originating from the sample
31、s is as complete as possible. Typical gas chromatographic conditions are given in annex A. NOTE 1: Due to their high separation efficiency, capillary columns are preferably used. NOTE 2: 2-chloroethanol is formed from chloride ions naturally occurring in the sample material. Its peak, however, has a
32、 shorter retention time and does not interfere with the determination. Test for interferences and recoveries 6.4 Prepare reagent blanks and carry out spiked recovery tests at levels appropriate to the maximum residue level. The chromatogram of the reagent blank should not show a peak at the retentio
33、n time of 2-bromoethanol. NOTE: Occasionally, a tailing peak with a longer retention time appears which is due to ethylene glycol and does not interfere with the determination. 7 Evaluation of results Measure the peak height (or peak area) obtained from the sample test solution and compare it with t
34、he peak heights (or peak areas) obtained for appropriate dilutions of the 2-bromoethanol standard solution (4.11). Based on this quotient, calculate the mass (A) of 2-bromoethanol, in nanograms, present in the injected sample test solution. Calculate the mass fraction w of bromide, in milligrams per
35、 kilogram of sample, using equation (I): Ax 25 x 0,639 Bx15 W= where: A is the mass of 2-bromoethanol in the injected volume of the sample test solution, in nanograms; B is the injection volume, in microlitres; 0,639 is the factor for conversion of 2-bromoethanol to bromide; 25 is the volume of the
36、organic solvents added in 6.2 in millilitres (20 ml of acetone and 5 ml of ethylene oxide solution); 15 is the mass of the aliquot of the test portion ashed in the nickel crucible, in grams. If the results indicate that the amount of residue approaches or exceeds the maximum residue level, examine a
37、t least two further test portions. 8 Confirmatory tests The bromide content can be confirmed with the derivatization method described in EN 13191-2:2000 3 using propylenoxide as reagent. O BSI 08-2000 Page 6 EN 13191-1:2000 9 Precision 9.1 General Details of the interlaboratory test of the precision
38、 of the method according to IS0 57251986 4 are summarized in annex B. The values derived from the interlaboratory test may not be applicable to analyte concentration ranges and matrices other than given in annex B. 9.2 Repeatability The absolute difference between two single test results found on id
39、entical test material by one operator using the same apparatus within the shortest feasible time interval will exceed the repeatability limit r in not more than 5 % of the cases. The values are: lettuce from untreated soil X = 13,3 mg/kg r= 3,6 mg/kg - lettuce from treated soil x = 209 mg/kg r= 35,O
40、 mg/kg 9.3 Reproducibility The absolute difference between two single test results on identical test material reported by two laboratories will exceed the reproducibility limit R in not more than 5 % of the cases. The values are: lettuce from untreated soil E = 13,3 mg/kg R= 6,9mg/kg - lettuce from
41、treated soil x = 209 mg/kg R= 75,O mg/kg 10 Test report The test report shall contain at least the following information: - all information necessary for the identification of the sample; - a reference to this European Standard or to the method used; -the results and the units in which the results h
42、ave 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 test; - any operations not specified in the method or regarded as optional which might have affected the results.
43、8 BSI 08-2000 STD-BSI BS EN L3LL-L-ENGL 2000 = Lb24bb 0b2975 b40 I Page 7 EN 131 91 -1 :2000 Annex A (informative) Examples for appropriate gas chromatographic operating conditions A.1 The following gas chromatographic operating conditions have been proven to be satisfactory. A.2 Packed glass column
44、s Column size Column filling Column temperature Injector temperature Carrier gas Column size Column filling Column temperature Injector temperature Carrier gas Column size Column filling Column temperature Injector temperature Carrier gas Column size Column filling Column temperature Injector temper
45、ature Carrier gas 1,80mx2mm 15 % PPG (UCON LB 550-X)*“ or 10 % Carbowax 20-M on Chromosorb W-HP, 150 pm to i90 pm (80 mesh to 100 mesh) 120 “C 130 “C nitrogen or argodmethane, flow rate 60 ml/min 1,80 m x 4 mm Tenax G/c, 190 pm to 250 pm (60 mesh to 80 mesh) 165 “C 175 “C nitrogen, flow rate 65 ml/m
46、in 1,80 mx2 mm 10 % OV-330 on Chromosorb W-HP, 150pm to 190pm (80 mesh to 100 mesh) 110C 150 OC nitrogen or argonlmethane, flow rate 30 mmin 130 m x 3 mm 10 % Carbowax 20-M on Chromosorb W-HP, 120pm to 150 pm (100 mesh to 120 mesh) 130 OC 200 OC nitrogen, flow rate 40 ml/min A.3 Capillary columns (f
47、used silica) Column size Column stationary phase Column temperature Injector temperature 250 “C Carrier gas 60 m x 0,53 mm Restek R-l701“), film thickness 3,O pm programmed to rise from 35 “C to 225 OC with 5 OC/min hydrogen, flow rate 5 mmin Column size Column stationary phase Column temperature In
48、jector temperature 250 “C Carrier gas 30 m x 0,53 mm Restek Stabilwax, film thickness 1 ,O pm programmed to rise from 40 “C to 225 OC with 5 “C/min hydrogen, flow rate 5 ml/min ) UCON LB 550-Pand Restek RTx-1701“ are examples of a suitable product available commercially. This information is given fo
49、r the convenience of users of this European Standard and does not constitute an endorsement by CEN of this product Q BSI 08-2000 STD.BSI BS EN L3LL-L-ENGL 2000 m Lb24bb9 08b297b 587 m Sample Lettuce (from untreated soil) Year of interlaboratory test 1975 Number of laboratories 8 Page 8 EN 13191-1:2000 Lettuce (from treated soil) 1975 8 Annex B (informative) Precision data Number of laboratories retained after eliminating outliers Number of outlying laboratories Number of samples Number of accepted results Mean value, x mg/kg Repeatability standard deviation s, mg/k
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