1、Designation:E219308Standard Test Method forUltraviolet Transmittance of Monoethylene Glycol(Ultraviolet Spectrophotometric Method)1This standard is issued under the fixed designation E2193;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revis
2、ion,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.Scope*1.1 This test method covers a procedure for the determina-tion of the transmittance of monoethylene glycol(1,2
3、-ethanediol;MEG)at wavelengths in the region 220 to 350 nm.The results provide a measure of the purity of the sample withrespect to ultraviolet absorbing compounds.1.2 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.3 This stan
4、dard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.1.4 Review the current Material
5、 Safety Data Sheets(MSDS)for detailed information concerning toxicity,first aidprocedures,and safety precautions.2.Referenced Documents2.1 ASTM Standards:2E131 Terminology Relating to Molecular SpectroscopyE169 Practices for General Techniques of Ultraviolet-VisibleQuantitative AnalysisE180 Practice
6、 for Determining the Precision of ASTMMethods for Analysis and Testing of Industrial and Spe-cialty Chemicals(Withdrawn 2009)3E275 Practice for Describing and Measuring Performance ofUltraviolet and Visible Spectrophotometers2.2 Other Document:Manufacturers Instruction Manual of Spectrophotometer3.S
7、ummary of Test Method3.1 The product is sampled in such a way as to avoidextraneous contamination and air contact.The absorbance ofthe sample contained in a 50-mm or 10-mm cell is measuredagainst water at a series of wavelengths and the transmittanceover a pathlength of 10 mm is calculated.3.2 This
8、test method can be performed with two options asto sample preparation prior to UV measurement.3.2.1 Option A:Nitrogen sparging of the sample(see 4.2).3.2.2 Option B:No nitrogen sparging.4.Significance and Use4.1 Knowledge of the ultraviolet transmittance of monoeth-ylene glycol is required to establ
9、ish whether the product meetsthe requirements of its quality specifications.4.2 Dissolved oxygen in organic solvents,such as MEG,forms complexes that shift the solvent absorption from thevacuum ultraviolet range into the measurable UV range(near190 to 250 nm).Monoethylene glycol has a UV absorptionp
10、eak at 180 nm.For MEG-oxygen complexes,this peak isshifted to a longer wavelength,thus increasing the absorbabil-ity at 220 nm.4.2.1 However,this effect is not observed in water.There isno significant measurable effect due to dissolved oxygen inwater that would require nitrogen sparging prior to usi
11、ng forcollection of the reference spectrum.4.2.2 Nitrogen sparging and re-measurement of suspect orborderline glycol samples at 220 nm can be used as a tool torule out or confirm the presence of UV affecting contaminantsother than oxygen.5.Apparatus5.1 Ultraviolet Spectrophotometer,double beam,suita
12、blefor measurement at wavelengths in the region 200 to 400 nm,having a spectral bandwidth of 2.0 nm or less at 220 nm,wavelength accuracy 60.5 nm or less at 220 nm,wavelengthrepeatability 0.3 nm or less at 220 nm and a photometricaccuracy of 60.5%T or less,in the transmittance regionabove 50%T.Stray
13、 light shall be less than 0.1%at 220 nm.The instrument shall be provided with matched fused silicacells with pathlengths of 50 6 0.1 mm or 10 mm 6 0.01 mm.Use of 50-mm cell should provide better precision.1This test method is under the jurisdiction of ASTM Committee E15 onIndustrial and Specialty Ch
14、emicalsand is the direct responsibility of SubcommitteeE15.02 on Product Standards.Current edition approved April 1,2008.Published May 2008.Originallyapproved in 2002.Last previous edition approved in 2004 as E2193 04.DOI:10.1520/E2193-08.2For referenced ASTM standards,visit the ASTM website,www.ast
15、m.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard is referenced onwww.astm.org.*A Summary of Changes section appears at th
16、e end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 5.1.1 Optional Single Beam SpectrophotomerUse thesame cell for measurement of the blank and the sample.5.2 Nitrogen Stripping Apparatus(Option A,3.2.1),consist-ing of an oil-free pressure reducing valve to fit the nitrogencylinder,a control valve,vinyl tubing and a disposable glasspipette to be inserted in a 25-mL volumetric flask.Componentsshould be clean and free
