BS ISO 17780-2015 Animal and vegetable fats and oils Determination of aliphatic hydrocarbons in vegetable oils《动植物油脂 植物油中脂肪烃的测定》.pdf

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1、BSI Standards PublicationBS ISO 17780:2015Animal and vegetable fatsand oils Determinationof aliphatic hydrocarbons invegetable oilsBS ISO 17780:2015 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 17780:2015.The UK participation in its preparation was entrusted

2、 to TechnicalCommittee AW/307, Oilseeds, animal and vegetable fats and oils andtheir by-products.A list of organizations represented on this committee can beobtained on request to its secretary.This publication does not purport to include all the necessaryprovisions of a contract. Users are responsi

3、ble for its correctapplication. The British Standards Institution 2015. Published by BSI StandardsLimited 2015ISBN 978 0 580 80481 6ICS 67.200.10Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of theStandards Pol

4、icy and Strategy Committee on 31 August 2015.Amendments issued since publicationDate Text affectedBS ISO 17780:2015 ISO 2015Animal and vegetable fats and oils Determination of aliphatic hydrocarbons in vegetable oilsCorp gras dorigines animale et vgtale Dtermination des hydrocarbures aliphatiques en

5、 corps gras dorigines vgtaleINTERNATIONAL STANDARDISO17780First edition2015-08-15Reference numberISO 17780:2015(E)BS ISO 17780:2015ISO 17780:2015(E)ii ISO 2015 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2015, Published in SwitzerlandAll rights reserved. Unless otherwise specified, no part o

6、f this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below or ISOs member body

7、in the country of the requester.ISO copyright officeCh. de Blandonnet 8 CP 401CH-1214 Vernier, Geneva, SwitzerlandTel. +41 22 749 01 11Fax +41 22 749 09 47copyrightiso.orgwww.iso.orgBS ISO 17780:2015ISO 17780:2015(E)Foreword ivIntroduction v1 Scope . 12 Normative references 13 Terms and definitions

8、. 14 Principle 25 Reagents 26 Apparatus . 37 Sampling 48 Preparation of the test sample . 59 Procedure. 59.1 Chromatography column preparation 59.1.1 Preparation of AgNO3impregnated silica gel . 59.1.2 Column packing 59.2 Elution of the hydrocarbon fraction . 59.3 Gas chromatography 69.3.1 Gas chrom

9、atography setup . 69.3.2 Working conditions for gas chromatography analysis 69.3.3 Peak identification 69.3.4 Performance of the gas chromatography system 79.4 Procedural blank . 79.5 Quantitative determination . 710 Determination of hydrocarbons attributed to mineral origin .1111 Precision 1111.1 I

10、nterlaboratory test 1111.2 Repeatability 1111.3 Reproducibility 1112 Test report 11Annex A (informative) Examples of chromatograms 12Annex B (informative) Validation of silver nitrate impregnated silica gel purification .17Annex C (informative) Procedure for rapid method .19Annex D (informative) Fat

11、 extraction from food sample 23Annex E (informative) Results of interlaboratory trials .26Bibliography .29 ISO 2015 All rights reserved iiiContents PageBS ISO 17780:2015ISO 17780:2015(E)ForewordISO (the International Organization for Standardization) is a worldwide federation of national standards b

12、odies (ISO member bodies). The work of preparing International 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 organizati

13、ons, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.The procedures used to develop this document and those intended for its furthe

14、r maintenance are described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the different types of ISO documents should be noted. This document was drafted in accordance with the editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives

15、).Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any patent rights identified during the development of the document will be in the Intro

16、duction and/or on the ISO list of patent declarations received (see www.iso.org/patents).Any trade name used in this document is information given for the convenience of users and does not constitute an endorsement.For an explanation on the meaning of ISO specific terms and expressions related to co

17、nformity assessment, as well as information about ISOs adherence to the WTO principles in the Technical Barriers to Trade (TBT) see the following URL: Foreword - Supplementary informationThe committee responsible for this document is ISO/TC 34, Food products, Subcommittee SC 11, Animal and vegetable

18、 fats and oils.iv ISO 2015 All rights reservedBS ISO 17780:2015ISO 17780:2015(E)IntroductionThe major saturated hydrocarbons present in vegetable oils are long chain n-alkanes, containing more than 21 carbon atoms, and having an odd carbon number preference.1Mineral oils can contain n-alkanes with u

19、p to 60 carbon atoms with no odd carbon predominance. Chromatograms of mineral oils obtained by this method are characterized by a wide peak due to the presence of a complex mixture of saturated branched and cyclic hydrocarbons. Medium and low viscosity mineral oils are typically characterized by a

20、complex mixture with between C10 and C25 chain length; while high viscosity mineral oils are indicated by a complex mixture with the midpoint around C30 chain length.2The Joint FAO/WHO Expert Committee on Food Additives (JECFA) has set several ADIs for mineral oil (2002) dividing low-medium viscosit

21、y mineral oils into three different subclasses depending on the point of toxicity. This method does not help to distinguish between different classes.Chromatograms of diesel oil are characterized by the presence of n-alkanes between C10 and C25 chain length with no odd carbon predominance, i.e. both

22、 even and odd numbered hydrocarbons are present in relatively equal proportions. ISO 2015 All rights reserved vBS ISO 17780:2015BS ISO 17780:2015Animal and vegetable fats and oils Determination of aliphatic hydrocarbons in vegetable oils1 ScopeThis International Standard specifies a method for the d

23、etermination of saturated aliphatic hydrocarbons from C10 to C56 of natural origin present in vegetable oils, and for detecting the presence of mineral oil and diesel oil.The method is applicable to all types of crude and refined edible oils and fats, for concentrations of mineral oils from 50 mg/kg

24、 to 1 000 mg/kg.A rapid method for refined and virgin (or cold-pressed) oils is proposed in Annex C. This rapid method is not adapted for crude oils due to a lack of retention of triglycerides observed for some samples.A method for fat recovery from food samples by soxhlet extraction with a blend of

25、 solvents is proposed in Annex D.2 Normative referencesThe following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenc

26、ed document (including any amendments) applies.ISO 661, Animal and vegetable fats and oils Preparation of test sample3 Terms and definitionsFor the purposes of this document, the following terms and definitions apply.3.1hydrocarbon contentssum of saturated aliphatic hydrocarbons, expressed as a mass

27、 fraction, determined according to the method specified3.2unresolved complex mixtureUCMcomplex mixture of saturated hydrocarbons not resolved by gas chromatography, represented by a wide peak, which can be due to a contamination with mineral oilNote 1 to entry: The width of the peak is approximately

28、 5 min to 15 min depending on gas chromatography conditions,Note 2 to entry: See relevant chromatograms in Annex A.3.3dieselsum of saturated n-alkanes between C10 and C25 chain length, expressed as a mass fraction, determined according to the methodNote 1 to entry: See relevant chromatograms in Anne

29、x A.INTERNATIONAL STANDARD ISO 17780:2015(E) ISO 2015 All rights reserved 1BS ISO 17780:2015ISO 17780:2015(E)4 PrincipleThe saturated aliphatic hydrocarbons of the sample are isolated by liquid chromatography on silica gel impregnated with silver nitrate and determined by capillary gas chromatograph

30、y with flame ionization detection using an internal standard. From the chromatogram, the area attributed to mineral oil is calculated by the subtraction of sharp peaks due to n-alkanes (naturally occurred hydrocarbons) from the total area including the UCM. To indicate diesel contamination, the peak

31、 areas of individual hydrocarbons between C10 and C25 chain length are summed and quantified together.5 ReagentsWARNING Attention is drawn to national regulations that specify the handling of hazardous substances, and users obligations thereunder. Technical, organizational and personal safety measur

32、es shall be followed.Unless otherwise specified, use only reagents of recognized analytical grade.5.1 Silica gel 601), extra pure for column chromatography with particle size between 60 m and 200 m (70-230 mesh).5.2 Water, distilled and cooled down to room temperature.5.3 Anhydrous sodium sulfate, a

33、nalytical grade, purity 99 % minimum.NOTE Sodium sulfate may be replaced by sea sand, washed with n-hexane.5.4 n-Hexane, trace organic analysis grade, purity 99 % minimum, residue after evaporation maximum 2 mg/kg.NOTE 1 Hexane purity may be checked by concentrating 200 ml of n-hexane mixed with 2 m

34、l of internal standard solution (5.6) using a rotary evaporator, dissolving the residue in 0,2 ml of n-hexane and the analysis of 5 l by gas chromatography (9.3).NOTE 2 Hexane may be replaced by isooctane, n-heptane or a mixture of alkanes of boiling point 65 C to 70 C, as long as the residue after

35、evaporation is maximum 2 mg/kg. Solvents with higher boiling point than n-hexane take longer to evaporate. However, they are preferred due to the toxicity of hexane.5.5 Internal standard: n-octadecane (C18), purity 99 % minimum.n-Octadecane may be replaced by n-eicosane (C20). Before choosing one of

36、 these two compounds as the internal standard, it should be verified that there is no co-elution with other peaks from the sample to be analysed.n-Octadecane shall be replaced by naphthalene if the sample is contaminated with a diesel oil, in order to avoid the overlapping of the internal standard p

37、eak with the alkane peaks to be quantified.5.6 Solution of internal standard, mass concentration = 0,04 mg/ml.As an example, weigh to the nearest mg, approximately 50 mg of n-octadecane (5.5) and dilute to 25 ml with n-hexane (5.4), and then proceed with a second dilution of this mixture of 1 ml 50

38、ml with n-hexane. Store this solution at room temperature in order to maintain its stability.5.7 n-Decane (C10), purity 99 % minimum.1) Silica gel is available from Merck, reference 7754 or 7734. This reference is an example of a suitable product which is available commercially. This information is

39、given for the convenience of users of this International Standard and does not constitute an endorsement by ISO of this product.2 ISO 2015 All rights reservedBS ISO 17780:2015ISO 17780:2015(E)5.8 n-Decane solution, mass concentration = 0,04 mg/ml.As an example, weigh to the nearest mg, approximately

40、 50 mg of n-decane and dilute to 25 ml with n-hexane (5.4), and then proceed with a second dilution of this mixture of 1 ml 50 ml with n-hexane. Store this solution at room temperature in order to maintain its stability.5.9 Octatetracontane (C48), purity 99 % minimum. This standard is used to limit

41、the integration of the hump to a certain retention time that will correspond to the retention time of this hydrocarbon.5.10 Octatetracontane solution, mass concentration approximately = 0,08 mg/ml.As an example, weigh to the nearest mg approximately 2 mg of octatetracontane (5.9) and dilute to 25 ml

42、 of n-hexane (5.4). Store this solution at room temperature in order to maintain its stability.NOTE Solubility of octatetracontane in hexane is limited at room temperature, due to its high melting point. However, the concentration of the solution of octatetracontane does not need to be accurate as i

43、t is used only to determine the limit of integration for the mineral oil peak.5.11 Silver nitrate (AgNO3), analytical grade.5.12 Silver nitrate aqueous solution, mass concentration = 0,75 g/ml.As an example, to prepare silver nitrate silica gel for 3 columns, weigh approximately 4,5 g of silver nitr

44、ate in 6 ml of distilled water (5.2).5.13 Carrier gas for gas chromatography, helium or hydrogen.5.14 Auxiliary gases for flame ionization detector, hydrogen, air, and nitrogen suitable for gas chromatography.5.15 Alkane standard mixture C10 to C402), solution in non-polar solvent.5.16 Viscous paraf

45、fin and highly liquid paraffin3), solution in non-polar solvent.5.17 Solution of paraffin and n-octadecane, mass concentration of paraffin = 0,5 mg/ml, mass concentration of n-octadecane = 0,08 mg/ml.As an example, weigh to the nearest mg, approximately 500 mg of viscous paraffin (5.16) and 80 mg of

46、 n-octadecane (5.5) and dilute to 10 ml with n-hexane (5.4), and then proceed with a second dilution of this mixture of 1 ml 100 ml with n-hexane. Store this solution at room temperature in order to maintain its stability.6 ApparatusUsual laboratory apparatus and, in particular, the following.IMPORT

47、ANT The glassware used for the determination shall be thoroughly cleaned and rinsed with n-hexane (5.4) before use so that it is free from impurities.2) Alkane standard mixture at 50 mg/l is available from Sigma-Aldrich, reference 68281 (). This reference is an example of suitable products which are

48、 available commercially. This information is given for the convenience of users of this International Standard and does not constitute an endorsement by ISO of these products.3) A viscous paraffin is available from Merck, reference 107160. Highly liquid paraffin is available from Merck, reference 10

49、7174. This information is given for the convenience of users of this International Standard and does not constitute an endorsement by ISO of these products. ISO 2015 All rights reserved 3BS ISO 17780:2015ISO 17780:2015(E)6.1 Glass column for chromatography (30 cm to 40 cm length and 15 mm to 20 mm internal diameter), fitted with sintered glass discs and polytetrafluoroethylene (PTFE) stop cock.NOTE A pad of cotton wool exhaustively extracted with n-hexane may be used to replace the sintered gla