BS EN 61198-1994 Mineral insulating oils - Methods for the determination of 2-furfural and related compounds《绝缘矿物油 2-糖醛和有关化合物测定方法》.pdf

1、BRITISH STANDARD BS EN 61198:1994 IEC 1198:1993 Mineral insulating oils Methods for the determination of 2-furfural and related compounds The European Standard EN61198:1994 has the status of a British Standard UDC 621.315.615.2:610.1:543.8BS EN61198:1994 This British Standard, having been prepared u

2、nder the directionof the Cables and Insulation Standards Policy Committee, was published underthe authority of the Standards Board and comes into effect on 15June1994 BSI 11-1999 The following BSI references relate to the work on this standard: Committee reference CIL/10 Draft for comment 92/03950 D

3、C ISBN 0 580 23385 5 Cooperating organizations The European Committee for Electrotechnical Standardization (CENELEC), under whose supervision this European Standard was prepared, comprises thenational committees of the following countries: Austria Italy Belgium Luxembourg Denmark Netherlands Finland

4、 Norway France Portugal Germany Spain Greece Sweden Iceland Switzerland Ireland United Kingdom Amendments issued since publication Amd. No. Date CommentsBS EN61198:1994 BSI 11-1999 i Contents Page Cooperating organizations Inside front cover National foreword ii Foreword 2 Text of EN 61198 3 Nationa

5、l annex NA (informative) Committees responsible Inside back cover National annex NB (informative) Cross-references Inside back coverBS EN61198:1994 ii BSI 11-1999 National foreword This British Standard has been prepared under the direction of the Cables and Insulation Standards Policy Committee and

6、 is the English language version of EN61198:1994 Mineral insulating oils Methods for the determination of 2-furfural and related compounds, published by the European Committee for Electrotechnical Standardization (CENELEC). It is identical with IEC1198:1993 published by the International Electrotech

7、nical Commission (IEC). WARNING. This British Standard calls for the use of substances and procedures that may be injurious to health if adequate precautions are not taken. It refers only to technical suitability and does not absolve the user from legal obligations relating to health and safety at a

8、ny stage. 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 document

9、comprises a front cover, an inside front cover, pages i and ii, the EN title page, pages 2 to 12, an inside back cover and a back cover. This standard has been updated (see copyright date) and may have had amendments incorporated. This will be indicated in the amendment table on the inside front cov

10、er.EUROPEAN STANDARD NORME EUROPENNE EUROPISCHE NORM EN 61198 March 1994 UDC 621.315.615.2:610.1:543.8 Descriptors: Liquid electrical insulating materials, mineral oils, chemical analysis, determination, furfural, extraction methods, chromatography analysis, high performance liquid, chromatography E

11、nglish version Mineral insulating oils Methods for the determination of2-furfural and related compounds (IEC 1198:1993) Huiles minrales isolantes Mthodes pour la dtermination du 2-furfural et ses drivs (CEI 1198:1993) Isolierle auf Minerallbasis Prfverfahren zur Bestimmung von Fur-fural und verwandt

12、en Verbindungen (IEC 1198:1993) This European Standard was approved by CENELEC on1993-12-08. CENELEC members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-

13、date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to any CENELEC member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation und

14、er the responsibility of a CENELEC member into its own language and notified to the Central Secretariat has the same status as the official versions. CENELEC members are the national electrotechnical committees of Austria, Belgium, Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy,

15、Luxembourg, Netherlands, Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom. CENELEC European Committee for Electrotechnical Standardization Comit Europen de Normalisation Electrotechnique Europisches Komitee fr Elektrotechnische Normung Central Secretariat: rue de Stassart 35, B-1050 B

16、russels 1994 Copyright reserved to CENELEC members Ref. No. EN 61198:1994 EEN61198:1994 BSI 11-1999 2 Foreword The text of document 10(CO)270, as prepared by IEC Technical Committee10: Fluids for electrotechnical applications, was submitted to the IEC-CENELEC parallel vote in October1992. The refere

17、nce document was approved by CENELEC as EN61198 on8December1993. The following dates were fixed: Annexes designated “normative” are part of the body of the standard. In this standard, Annex A andAnnex ZA are normative. Contents Page Foreword 2 Introduction 3 1 Scope 3 2 Normative references 3 3 Samp

18、ling 3 4 Labelling of samples 3 5 Apparatus 3 5.1 General equipment 3 5.2 Equipment for extraction by Method A 3 5.3 Equipment for extraction by Method B 3 5.4 High-performance liquid chromatograph(HPLC) 3 6 Reagents 3 7 Symbols and units 4 8 Analytes 4 9 Operating procedure 4 9.1 Extraction of the

19、analytes 4 9.2 Analysis of the extract 4 10 Calibration 5 10.1 Standard solutions in oil 5 10.2 Standard solution in the chromatographiceluent 5 10.3 Procedure 5 11 Calculations 5 12 Report 5 13 Minimum level of detection 6 14 Precision 6 14.1 Repeatability 6 14.2 Reproducibility 6 Annex A (normativ

20、e) Checking extraction and recovery 7 Annex ZA (normative) Other international publications quoted in this standard with the references of the relevant European publications 12 Figure 1 Example of suitable device for extraction with silica cartridge (method B) 8 Figure 2 Examples of chromatograms re

21、corded at two wavelengths (220 nm and 276 nm) 9 Figure 3 UV spectra of the 2-furfural derivates 11 latest date of publication of an identical national standard (dop) 1994-12-01 latest date of withdrawal of conflicting national standards (dow) 1994-12-01EN61198:1994 BSI 11-1999 3 Introduction The deg

22、radation of cellulosic materials constituting the solid insulation of oil-filled electrical equipment leads to the formation of several compounds specific to cellulose decomposition, such as sugars and furan derivatives. The furan derivatives, of which a large proportion remains adsorbed on the pape

23、r, are nevertheless slightly soluble in oil. Their presence can be used as a diagnostic tool to equipments in service and to supplement information from dissolved gas analysis. 1 Scope This International Standard specifies test methods for the analysis of 2-furfural and related furan compounds resul

24、ting from the degradation of cellulosic insulation and found in mineral insulating oil samples taken from electrical equipment. 2-furfural and related furan compounds dissolved in mineral oil are analysed by high performance liquid chromatography (HPLC). Prior to HPLC analysis, furan derivatives are

25、 extracted from the oil by use of a suitable extraction method such as liquid-liquid extraction (method A) or solid-phase separation on a silica cartridge (method B). 2 Normative references The following normative documents contain provisions which, through reference in this text, constitute provisi

26、ons of this International Standard. At the time of publication of this standard, the editions indicated were valid. All normative documents are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recen

27、t editions of the normative documents indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. IEC 475:1974, Method of sampling liquid dielectrics. IEC 567:1992, Guide for the sampling of gases and of oil from off-filled electrical equipment and for the

28、analysis of free and dissolved gases. 3 Sampling Oil samples are collected in accordance with IEC475 and IEC567. Samples should be protected from direct light. 4 Labelling of samples Samples shall be labelled in accordance with IEC567. 5 Apparatus 5.1 General equipment: laboratory glassware; beakers

29、 or Erlenmeyer flasks; volumetric flasks; pipettes; analytical balance (0,1 mg). 5.2 Equipment for extraction by method A 25 ml glass stoppered graduated cylinder; 5 ml pipette; mechanical shaker. 5.3 Equipment for extraction by method B silica cartridges, containing about1g of silica with a particl

30、e size ranging from154m to1004m. Commercially available cartridges are suitable; a vacuum device suitable to produce a slight vacuum (i.e. filter pump or vacuum manifold), seeFigure 1; a 10 ml luer lock syringe; volumetric flasks, 2 ml. 5.4 High-performance liquid chromatograph (HPLC) A high-perform

31、ance liquid chromatograph equipped with: pumping system suitable for at least two solvents; injection device capable of injecting104l to204l and suitable precision syringe (504l to2504l); reversed phase column packed with octyl or octadecyl bonded silica; pre-column packed with the same material as

32、the analytical column (optional); UV detector capable of recording UV spectra; a diode array UV detector is recommended; data acquisition system (recorder or integrator). 6 Reagents HPLC grade acetonitrile; HPLC grade methanol; HPLC grade water; HPLC grade acetic acid; Analytical grade n-pentane; An

33、alytical grade analytes as listed in clause8.EN61198:1994 4 BSI 11-1999 7 Symbols and units 8 Analytes Analytical conditions shall be suitable for the determination of the following furan derivatives: For the purpose of this standard the determination of furoic acids is optional as it is often diffi

34、cult to resolve them from other organic acids that may be present in aged mineral insulating oil samples. 9 Operating procedure 9.1 Extraction of the analytes 9.1.1 Method A: liquid-liquid extraction Extract approximately20ml of oil sample, weighed to the nearest0,1g, with5ml of acetonitrile, measur

35、ed by a pipette, in a25ml stoppered cylinder, shaking the samples on a mechanical shaker for at least2min. Allow the samples to stand until the solvent and oil layers separate completely. The extract can then be analysed as described in9.2. NOTEThe time period necessary for phase separation tends to

36、 increase for oils with higher acid values. 9.1.2 Method B: solid-liquid extraction Weigh exactly10g 0,1g of oil sample and dissolve it in10ml analytical grade n-pentane. Rinse a new silica cartridge with2ml n-pentane and discard the eluate. While the silica is still wet, immediately pass the sample

37、 solution through the cartridge under a slight vacuum at a maximum flow of3ml/min followed by20ml n-pentane. Discard all eluates. Dry the cartridge by suction by maintaining the vacuum for at least5min. Release the vacuum and elute the retained material with the same eluent used in the first minutes

38、 of the chromatogram (see9.2), using a10ml syringe as the dispenser. Collect the first two millilitres in a2ml volumetric flask. NOTEAnnex A describes a method to assess the efficiency of the silica cartridge. 9.2 Analysis of the extract 9.2.1 Adjust the liquid chromatograph in accordance with the m

39、anufacturers instructions and establish suitable operating conditions. 9.2.2 The following set of conditions has been found satisfactory but some adjustments may be appropriate depending upon specific features of the instrumentation and local conditions. 9.2.3 The UV detector shall monitor the follo

40、wing wavelengths: 220 nm for 2-furfurylalcohol. 275 nm to 280 nm for all other compounds listed in clause8. NOTEMaximum light absorption occurs at approximately the following wavelengths: Selection of the above wavelengths will enhance the sensitivity of the analysis for specific compounds. 9.2.4 Wh

41、en the chromatograph and detector are equilibrated inject an aliquot of the extract and record the detector response. Examples of typical chromatograms are shown inFigure 2. 9.2.5 After elution of the last peak of interest (5-methyl-2-furfural with specified columns) switch the mobile phase to100% m

42、ethanol or acetonitrile and increase the flow rate until all oil residues have been flushed out of the column. F i Detector response factor for each of the analytes. Detector response for each analyte in the calibration standards (the response may be expressed by peak area or peak height). R i Detec

43、tor response for each of the detected analytes. (mgkg 1 ) Concentration of each analyte in the calibration standards. C i (mgkg 1 ) Concentration of each of the analytes in the mineral insulating oil sample. 5-hydroxymethyl-2-furfural (5HMF) 2-furfurylalcohol (2FOL) 2-furfural (2FAL) 2-acetylfuran (

44、2ACF) 5-methyl-2-furfural (5MEF) R i s C i s isocratic conditions; eluent: water60% to80% in volume; methanol or acetonitrile20% to40% in volume; flow rate: 0,5 to 2,0 ml/min. NOTEIn some cases an elution gradient may be useful to improve the separation. Also the addition of a small amount of acetic

45、 acid (0,01 %) may improve the separation of the more polar compounds. 5-hydroxymethyl-2-furfural 280 nm 2-furfurylalcohol 215 nm 2-furfural 274 nm 2-acetylfuran 272 nm 5-methyl-2-furfural 288 nmEN61198:1994 BSI 11-1999 5 10 Calibration Standard solutions in oil are required to calibrate analyses of

46、 extracts obtained from method A. Standard solutions either in oil or in chromatographic eluent may be used with extracts prepared in accordance with method B. 10.1 Standard solutions in oil 10.1.1 Preparation of stock solution dissolve 0,025g of each of the five compounds in25ml toluene (concentrat

47、ion1000mg/l); stock solutions shall be stored in a brown glass bottle and kept in the dark. They should be replaced at intervals of not more than three months. 10.1.2 Preparation of standard solutions dilute an aliquot of the toluene stock solution in a weighed amount of unused mineral insulating oi

48、l to prepare a standard solution of the desired concentration (i.e. 0,5, 1,0, 5 or10 mg/kg); store in brown glass bottles and keep in the dark. NOTE 1Select an appropriate mineral insulating oil which is free from species likely to interfere with the analytes. NOTE 2Standard solutions deteriorate ra

49、pidly if they are not properly stored. Freshly-prepared solutions are preferred. 10.2 Standard solution in the chromatographic eluent If method B is used, an alternative easier and faster calibration procedure may be used: weigh 0,015 g of each of the five compounds; dissolve them in100ml of the chromatographic eluent to obtain a stock solution of about150mg/l; dilute the stock solution to obtain a standard solution of the desired concentration (i.e. 2,5, 5