ASTM_D_3125_-_06_2012.pdf

Designation:D312506(Reapproved 2012)Standard Test Method forMonomethyl Ether of Hydroquinone in Colorless MonomericAcrylate Esters and Acrylic Acid1This standard is issued under the fixed designation D3125;the number immediately following the designation indicates 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.Scope*1.1 This test method covers the determination of monom-ethyl ether of hydroquinone2(MEHQ)in colorless monomericacrylate esters and acrylic acid.The test method is applicableto the determination of MEHQ in the concentration range from0 to 1200 parts per million.1.2 For purposes of determining conformance of an ob-served or a calculated value using this test method to relevantspecifications,test result(s)shall be rounded off“to the nearestunit”in the last right-hand digit used in expressing thespecification limit,in accordance with the rounding-off methodof Practice E29.1.3 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.4 For hazard information and guidance,see the suppliersMaterial Safety Data Sheet.1.5 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of whoever uses this standard to consult andestablish appropriate safety and health practices and deter-mine the applicability of regulatory limitations prior to use.Specific precautionary statements are given in Section 8.2.Referenced Documents2.1 ASTM Standards:3D1193 Specification for Reagent WaterE29 Practice for Using Significant Digits in Test Data toDetermine Conformance with SpecificationsE180 Practice for Determining the Precision of ASTMMethods for Analysis and Testing of Industrial and Spe-cialty Chemicals(Withdrawn 2009)43.Summary of Test Method3.1 As shown in the equation,MEHQ reacts with nitrousacid(sodium nitrite in acidic media)to form the nitrosoderivative which equilibrates between two structures.3.2 The yellow color of the nitroso compound is measuredspectrophotometrically at a wavelength of 420 nm.4.Significance and Use4.1 Acrylic acid and its esters are normally inhibited withMEHQ only.This procedure presents a rapid and accuratemethod of determining the MEHQ content of fresh acrylic acidand acrylate esters in the absence of other inhibitors.4.2 MEHQ effectiveness may decline with age and thisdecline in effectiveness may not be indicated by this testmethod.5.Interferences5.1 Hydroquinone(HQ),thiodiphenylamine,diphenylphenylene-diamine and p-hydroxydiphenylamine in-terfere if present.6.Apparatus6.1 Spectrophotometer,with borosilicate-glass cells for de-termining absorbance at 420 nm.6.2 Volumetric Flasks,50 and 100-mL capacity.6.3 Measuring Pipets,5 and 10-mL capacity.7.Reagents7.1 Purity of ReagentsReagent grade chemicals shall beused.Unless otherwise indicated,it is intended that all reagents1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings,Materials,and Applications and is the direct responsibility ofSubcommittee D01.35 on Solvents,Plasticizers,and Chemical Intermediates.Current edition approved June 1,2012.Published July 2012.Originally approvedin 1972.Last previous edition approved in 2006 as D3125 06.DOI:10.1520/D3125-06R12.2IUPAC-approved name is 4-methoxyphenol.3For referenced ASTM standards,visit the ASTM website,www.astm.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.4The last approved version of this historical standard is referenced onwww.astm.org.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 shall conform to the specifications of the Committee onAnalytical Reagents of the American Chemical Society wheresuch specifications are available.5Other grades may be used,provided it is first ascertained that the reagent is of sufficientlyhigh purity to permit its use without lessening the accuracy ofthe determination.7.2 Purity of WaterUnless otherwise indicated,referencesto water shall be understood to mean reagent grade waterconforming to Type IV of Specification D1193.7.3 Acetic Acid,glacial.7.4 Monomethyl Ether of Hydroquinone(MEHQ)(4-methoxyphenol).7.5 Sodium Nitrite Solution(2%)Dissolve 2 g of sodiumnitrite(NaNO2)in water and dilute to 100 mL.8.Hazards8.1 Store samples of acrylic monomers in amber bottles orprotect from light by other means to aid in preventingpolymerization.Keep samples away from heat sources andchemicals that can cause free radical polymerization.Acrylicmonomers can polymerize violently,evolving considerableheat.Keep sample container size to a minimum.The inhibitor,monomethyl/est