1、Designation:D 1358 86(Reapproved 1995)e1Standard Test Method forSpectrophotometric Diene Value of Dehydrated Castor Oiland Its Derivatives1This standard is issued under the fixed designation D 1358;the number immediately following the designation indicates the year oforiginal adoption or,in the case
2、 of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon(e)indicates an editorial change since the last revision or reapproval.e1NOTEUnit of measurement statement and Keywords were added editorially in May 1995.1.Scope1.1 This test met
3、hod covers the determination of the spec-trophotometric diene value as a measure of the content ofconjugated dienoic acids in dehydrated castor oil and itsderivatives.Due to the high linoleic acid content in dehydratedcastor oil and its derivatives,the absolute conjugated dienoicacid content cannot
4、be determined by this test method.1.2 The values stated in SI units are to be regarded as thestandard.The values given in parentheses are for informationonly.1.3 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of
5、this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.Specific hazardstatements are given in Section 6.2.Terminology2.1 Description of Term Specific to This Standard:2.1.1 spectrophotometric diene valueunder the co
6、nditionsof this test method,the percent of conjugated dienoic acids.3.Significance and Use3.1 In the process of dehydrating castor oil,a double bondis formed in the ricinoleic acid to make either conjugatedlinoleic or normal linoleic fatty acid segments in the oil.Thistest method attempts to measure
7、 the amount of conjugatedunsaturation by means of the absorbance at a specific wave-length which is in the ultraviolet range.Since some absorptionis due to linoleic acid,a correction factor is included in thecalculation.This test method is only applicable to dehydratedcastor oil products.4.Apparatus
8、4.1 SpectrophotometerUltraviolet photoelectric spectro-photometer,2covering a spectral range from 200 to 350 nm,with a wavelength scale readable to 0.1 nm,and equipped withan absorption cell compartment3for holding 10.00-mm cells.4.2 Absorption Cells,quartz,matched pairs of lengths 10.006 0.05 mm.Th
9、e cells in a pair,when filled with water orisooctane,shall match within 0.01 absorbancy unit(Note 1).The cells may be the 10.00-mm nondemountable type made ofquartz,or the demountable type consisting of a chemicallyresistant glass4cell body of outside diameter of about 22 mmwith centered-ground glas
10、s stopper,threaded metal caps,pol-ished crystalline quartz windows,and cork gaskets.NOTE1If the cells do not match within 0.01 absorbancy unit,theymay be filled with water or isooctane and calibrated against each other atthe specified wavelength.The necessary correction in absorbancy units isthen ap
11、plied where necessary.Highest precision is obtained by the methodof reversing cells.The absorbancy of the solution is read against thesolvent blank.The cells are then cleaned and the solvent blank put in thecell previously used for the solution and the solution in the cell previouslyused for the bla
12、nk and the absorbancy measured.The two absorbancies arethen averaged to obtain As,the observed absorbancy.The cells should berinsed with solvent,water,concentrated nitric acid,water,and solvent,inthat sequence,before each reading.4.3 Filter Tube,810 by 45 mm(32 by 134in.).4.4 Cork Stopper covered wi
13、th aluminum foil to fit looselyin the top of the filter tube.4.5 Dropping Bottle,stoppered,for weighing the samples.4.6 Volumetric Flasks,glass-stoppered,having capacities of100 mL,50 mL,and 25 mL.4.7 Volumetric Pipets,precision grade,assorted sizes,formaking dilutions when required.5.Reagents and M
14、aterials5.1 Silica Gel,28 to 200-mesh.51This test method is under the jurisdiction of ASTM Committee D-1 on Paintand Related Coatings,Materials,andApplications,and is the direct responsibility ofSubcommittee D01.32 on Drying Oils.Current edition approved March 27,1986.Published May 1986.Originallypu
15、blished as D 1358 55 T.Last previous edition D 1358 58(1984)e1.2The Beckman Model DU photoelectric quartz spectrophotometer,Catalog No.2500 DU,Beckman Laboratories,S.Pasadena,CA,has been found satis-factory for this purpose.3The cell compartment assembly,as Catalog No.2510,and the ultravioletaccesso
16、ry set,as Catalog No.2501,that includes the No.2230 hydrogen dischargelamp,the No.2511 adapter,No.23-10-10-89 cells,and No.2504 cover,bothavailable from Beckman Laboratories,S.Pasadena,CA,have been found satis-factory for this purpose.4Borosilicate glass has been found satisfactory for this purpose.5Silica gel available from Davison Chemical Co.,Baltimore,MD,as Code11-08,or the equivalent,has been found satisfactory for this purpose.1AMERICAN SOCIETY FOR TESTING AND MATERIALS100 Barr Harbor Dr.,
