1、Designation:D583799 (Reapproved 2005) Designation: D5837 12Standard Test Method forFuranic Compounds in Electrical Insulating Liquids by High-Performance Liquid Chromatography (HPLC)1This standard is issued under the fixed designation D5837; the number immediately following the designation indicates
2、 the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination in el
3、ectrical insulating liquids of products of the degradation of cellulosicmaterials such as paper, pressboard, and cotton materials typically found as insulating materials in electrical equipment. Thesedegradation products are substituted furan derivatives, commonly referred to as furanic compounds or
4、 furans. This test methodallows either liquid/liquid or solid phase extraction (SPE) of the furanic compounds from the sample matrix followed by analysisfor specific furanic compounds by HPLC or direct injection for analysis of specific furanic compounds by HPLC.1.2 The individual furanic compounds
5、that may be identified and quantified include the following:5-hydroxymethyl-2-furaldehydefurfuryl alcohol2-furaldehyde2-acetylfuran5-methyl-2-furaldehyde1.3 The direct injection method generally has a higher limit of detection, especially for furfuryl alcohol. Greater interferencefor furfuryl alcoho
6、l may be expected when using the direct injection method as opposed to extraction methods.1.4 This test method has been used to successfully test for furanic compounds in mineral insulating oil, silicone fluid, high firepoint electrical insulating oils of mineral origin, askarels, and perchloroethyl
7、ene-based dielectric fluids.1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of
8、this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D923 Practices for Sampling Electrical Insulating LiquidsD3487 Specification for Mineral Insulating Oil Used in Electric
9、al ApparatusD3612 Test Method for Analysis of Gases Dissolved in Electrical Insulating Oil by Gas ChromatographyD3613Practice for Sampling Insulating Liquids for Gas Analysis and Determination of Water Content Test Method for Analysisof Gases Dissolved in Electrical Insulating Oil by Gas Chromatogra
10、phy2.2 International Electrotechnical Commission (IEC) Standard:Method 1198 Furanic Compounds Analysis in Mineral Oil Insulating Oil33. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 adsorbent, nthe stationary phase in solid-phase extraction; silica is used as the adsorbent in t
11、his test method.3.1.2 extract, nthe liquid phase of a liquid/liquid extraction containing the compound that has been extracted and that willbe analyzed.3.1.3 liquid/liquid extraction, nthe preparative step of extraction by mixing nonpolar test specimen with polar solvent to1This test method is under
12、 the jurisdiction of ASTM Committee D27 on Electrical Insulating Liquids and Gases and is the direct responsibility of Subcommittee D27.03on Analytical Tests.Current edition approved Oct. 1, 2005. Published November 2005. Originally approved in 1995. Last previous edition approved in 1999 as D583799
13、1. DOI:10.1520/D5837-99R05.Current edition approved Feb. 1, 2012. Published February 2012. Originally approved in 1995. Last previous edition approved in 2005 as D5837 99(2005). DOI:10.1520/D5837-12.2For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Servic
14、e at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.3Available from IEC, IEC Central Office, 3 rue de Varembe, P.O. Box 131, CH-1211, Geneva 20, Switzerland.1This document is not an ASTM standard and is intended
15、only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current ve
16、rsionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.preferentially partition and concentrate polar compounds of interest from an insulating liquid test sp
17、ecimen.3.1.4 mobile phase, nthe carrier liquid phase in an HPLC analytical system used to transfer the prepared test specimen to andthrough the analytical column and detector; the composition of the mobile phase affects elution time and separation of analytes.3.1.5 solid phase extraction (SPE), na p
18、reparative step based on column chromatography, where intermolecular interactionsbetween adsorbent, solvent, and test specimen components are optimized to effect retention of analytes on a solid-phase extractioncartridge, followed by solvent elution from the extraction cartridge.3.1.6 ultraviolet (U
19、V), adjreferring to that region of the electromagnetic spectrum including wavelengths from 10 to 380 nm.The UV detectors of most HPLC systems operate in the range of wavelengths from 190 to 380 nm.4. Summary of Test Method4.1 Furanic compounds in electrical insulating liquids are extracted from a kn
20、own volume of test specimen by means of aliquid/liquid extraction or solid-phase extraction. A direct injection of the oil also may be used.4.2 Aportion of the extract or an aliquot of the oil is introduced into an HPLC system equipped with a suitable analytical columnand UV detector.4.3 Furanic com
21、pounds in the test specimen are identified and quantified by comparison to standards of known concentration.5. Significance and Use5.1 Furanic compounds are generated by the degradation of cellulosic materials used in the solid insulation systems of electricalequipment.5.2 Furanic compounds which ar
22、e oil soluble to an appreciable degree will migrate into the insulating liquid.5.3 High concentrations or unusual increases in the concentrations of furanic compounds in oil may indicate cellulosedegradation from aging or incipient fault conditions. Testing for furanic compounds may be used to compl
23、ement dissolved gas inoil analysis as performed in accordance with Test Method D3612.6. Interferences6.1 Materials used in the manufacture of the polypropylene tubes and polyethylene frits of some commercially preparedsolid-phase extraction columns may interfere with the determination of furanic com
24、pounds, such as furfuryl alcohol and5-hydroxymethyl-2-furaldehyde.6.2 The use of acetone in any preparative or analytical step will cause accelerated sample decay and may interfere with theaccurate determination of 5-hydroxymethyl-2- furaldehyde.6.3 The use of cellulosic filtering media may serve to
25、 adsorb furanic compounds yielding erroneous or unreproducible results,or both.7. Apparatus7.1 High-Performance Liquid Chromatograph (HPLC)The required analytical apparatus, an HPLC, consists of an injectiondevice with sample loop, pumping system capable of mixing at least two solvents, reversed pha
26、se analytical column, UV detectoror detectors with the ability to operate at a minimum of two wavelengths, and a data recording device or integrator.7.2 It is recommended that a precolumn packed with the same material as the analytical column be used to increase column lifeand remove interferences.7
27、.3 Helium sparging of the mobile-phase solvents is recommended in some cases and with some types of HPLC equipment todisplace atmospheric gases dissolved in the mobile-phase solvents and to prevent the evolution of air bubbles.7.4 The analytical apparatus may be heated several degrees Celsius above
28、ambient if necessary to reduce variance in analyticalresults that may be caused by temperature fluctuations. Operation at ambient temperature or at a controlled temperature of 30 to40C has been found satisfactory by some laboratories.7.5 The following range of HPLC analytical conditions has been fou
29、nd to be satisfactory for extracted test specimens (specificexamples are given in the appendix):Injection Volume 15 to 30 LMobile Phase water/acetonitrile or water/methanol gradientFlow Rate 0.5 mL/min to 1.5 mL/minColumn Temperature ambient to 40CColumn 3.9 3 300 mm C18 60 to 125A, 4 to 10 m or 4.1
30、 3 150mm PRP-1 100 A, 5 to 10 mGradient see appendixNOTE 1Some laboratories have found it beneficial to filter all mobile phase solvents with a 0.45-m or smaller polytetrafluoroethylene or nylon filter.Store water in containers shielded from light. Some laboratories use 50 mL of methanol added to 4
31、L of water to inhibit biological growth.7.6 The following HPLC analytical conditions have been found to be satisfactory for direct injection of the oil:Injection volume 20 to 30 LMobile phase acetonitrile/water gradientFlow rate, initial 0.51.0 mL/minColumn temperature ambient to 30CD5837 122Column
32、WatersT Nova-Pak C18 Reversed Phased 300 3 3.9mm, 60A, 4 mGradient see Appendix7.7 For direct injection, a fixed wavelength between 274 and 281 nm has been found to provide the best chromatography forall compounds of interest, except furfuryl alcohol, which is best measured with a separate test usin
33、g a wavelength between 215and 220 nm. Each furanic compound has a characteristic maximum light absorbance occurring within the indicated ranges ofwavelengths. Use of variable wavelength or diode array detectors allows the selection of a specific wavelength for each furaniccompound. Each laboratory s
34、hall select the specific wavelength to yield maximum absorbance for each compound as follows:Furanic Compound nm5-hydroxymethyl-2-furaldehyde 280 to 282furfuryl alcohol 215 to 2202-furaldehyde 272 to 2802-acetyl furan 270 to 2805-methyl-2-furaldehyde 280 to 2927.8 After the last compound of interest
35、 elutes through the column, increase the acetonitrile or methanol to 100 % of the mobilephase to remove all oil contamination remaining in the analytical column.7.9 Readjust the solvent ratio of the mobile phase to the initial conditions and allow 10 to 15 min for the column to come toequilibrium pr
36、ior to the next injection.8. Reagents and Materials8.1 AcetonitrileHPLC grade.8.2 2-Acetylfuran99 % purity, CAS #1192-62-7.8.3 Electrical Insulating OilVirgin oil of mineral origin.8.4 2-Furaldehyde99 % purity, CAS #98-01-1.8.5 Furfuryl Alcohol99 % purity, CAS #98-00-0.8.6 HexaneHPLC grade.8.7 5-Hyd
37、roxymethyl-2-Furaldehyde 99 % purity, CAS #67-47-0.8.8 MethanolHPLC grade.8.9 5-Methyl-2-furaldehyde99 % purity, CAS #620-02-0.8.10 Silica SPE ColumnSolid-phase extraction column filled with 500 mg of silica.8.11 TolueneHPLC grade.8.12 Vacuum ManifoldDevice to pull vacuum on solid-phase extraction c
38、olumn in order to pass sample and eluent throughSPE column.8.13 Volumetric Test TubeTest tube designed to volumetrically measure in 0.10-mL graduations.8.14 Vortex Mixer.8.15 WaterHPLC grade.9. Sampling9.1 Obtain test specimens (insulating fluid samples) in accordance with the procedures for samplin
39、g in Practices D923orPractice D3613.10. Preparation of Extraction Standards in Solvent10.1 Prepare the extraction standards by dilution of a weighed standard compound to a standard volume or by volumetricaddition of a standard compound to a standard volume in accordance with either of the procedures
40、 described in 10.1.1 or 10.1.2.10.1.1 Weight ProcedureWeigh out 0.100 g 6 5 % of each of the five furanic compounds listed in this test method and recordthe weight to the nearest 0.1 mg. Dissolve weighed portions into 100 mL of acetonitrile or methanol. Take 1 mL of this solutionand add to a clean 1
41、-L volumetric flask. Add 199 mL of either acetonitrile or methanol, using the same solvent as was used earlierto dissolve the weighed portions of the furanic compounds. Bring the solution in the volumetric flask to 1 Lwith water. Other ratiosof solvent to water may be used such as to match that of t
42、he initial mobile phase. This solution yields a concentration of about1 mg/L (1000 g/L) of each of the furanic compounds. Use the actual mass of each compound to calculate the concentration. Storein a clean, dark plastic container. Do not store in glass.10.1.2 Volumetric AdditionFuranic compounds th
43、at are not liquid at ambient temperature should be heated to 35C where allof the compounds are in a liquid state. Use a 1-L syringe to add the indicated volumes of furanic compounds to 10 mL ofacetonitrile or methanol. The volumes to be added are as follows:0.83 L 6 1 % of 5-hydroxymethyl-2-furaldeh
44、yde0.88 L 6 1 % of furfuryl alcohol0.86 L 6 1 % of 2-furaldehyde0.91 L 6 1 % of 2-acetylfuran0.90 L 6 1 % of 5-methyl-2-furaldehyde10.1.2.1 These volumes represent a mass of 1000 g of each of the five furanic compounds. Add 10 mL of acetonitrile ormethanol containing the dissolved volumes of furanic
45、 compounds to 190 mL of the same solvent in a 1-L volumetric flask. BringD5837 123this solution to 1 L with water. Other ratios of solvent to water can be used such as to match that of the initial mobile phase. Theresulting concentration is 1 mg/L (1000 g/L) for each of the five furanic compounds. S
46、tore as indicated in 10.1.1.11. Preparation of Calibration Standards in Oil11.1 Prepare standards of furanic compounds in new dielectric liquid which has been tested and shown to have a flat baselinefor the range of retention times for the compounds of interest. Mineral oil shall otherwise conform t
47、o Specification D3487. Otherdielectric liquids should conform with applicable ASTM specifications.NOTE 2The same type of dielectric liquid should be used for standard preparation as the dielectric liquid found in the test specimen(s). This testmethod has been developed for mineral oil, but has been
48、found to be applicable to other dielectric fluids.11.2 Volumetric Preparation:11.2.1 Use a graduated 1-L syringe to inject volumes of the five furanic compounds as listed in 10.1.2 into 8 mL of toluene.Dissolve the compounds and add quantitatively to a 1-L volumetric flask. Make sure all compounds a
49、re thoroughly mixed.11.2.2 Dilute the 8 mL of toluene containing furanic compounds to a total volume of 1 L with electrical insulating oil of mineralorigin. The solution yields a concentration of 1 mg/L (1000 g/L) of each of the five furanic compounds. Store as described in10.1.1.11.3 Gravimetric Preparation:11.3.1 Weigh out 0.100 g 6 5 % of each of the five furanic compounds and record the weight to the nearest 0.1 mg. Dissolvethe weighed portion in toluene and dilute volumetrically to 100 mL in toluene. Mix thoroughly so that all
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