1、Designation:D571215Standard Test Method forAnalysis of Aqueous Extractable Protein in Latex,NaturalRubber,and Elastomeric Products Using the ModifiedLowry Method1This standard is issued under the fixed designation D5712;the number immediately following the designation indicates the year oforiginal a
2、doption 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 an analytical test for determin-ing the amount of to
3、tal aqueous extractable protein associatedwith NR,latex,and elastomeric products.Water solubleproteins are extracted in a buffer solution and then precipitatedto concentrate them and also to separate them from watersoluble substances that may interfere with the determination.The extracted protein is
4、 redissolved and quantified colorimetri-cally by the modified Lowry method using a protein standard.1.2 For the purpose of this test method,the range of proteinmeasurement will be based on the limit of detection andquantitation and recorded in micrograms per dm2test speci-men.1.3 The test method is
5、designed to be accurate and compat-ible with the industrial environment.1.4 Steps are included in this test method to minimize theeffects of interfering substances.1.5 It is recognized that other methods for the analysis ofleachable proteins exist and these may be used for routinequality control pur
6、poses provided they have been validated anda correlation established against the reference method specifiedby this test method.1.6 This test method has not been validated for use withlubricated products such as condoms.Condoms with differentlubricants as typically marketed,have not been tested in an
7、ASTM ILS to determine if,and if so to what degree,thelubricant interferes with the assay.1.7 This standard 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 a
8、nd determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D3577 Specification for Rubber Surgical GlovesD3578 Specification for Rubber Examination GlovesD4483 Practice for Evaluating Precision for Test MethodStandards in the Rubber and Carbon Bl
9、ack ManufacturingIndustries3.Terminology3.1 Definitions:3.1.1 backgroundthe absorbance measurement of theLowry assay in the absence of the protein analyte.3.1.2 calibrationthe standardization of an instrument set-ting.3.1.3 calibration solutionthe standard solution used toroutinely and reproducibly
10、calibrate a measuring instrument.3.1.4 concentration rangethe recommended analyte con-centration range in g/mL that produces an absorbance mea-surement of 0.01 to 1.5 units at 600 to 750 nm.3.1.5 dilution factor(F)the ratio of the volume NaOH inmillilitres used to redissolve the test specimen extrac
11、t tovolume NaOH in millilitres used to redissolve the standardovalbumin proteins.For example,if protein in a 1-mL testextract is acid precipitated and redissolved in 0.25 mL,and theovalbumin protein standards are also redissolved in 0.25 mL,then the dilution factor ratio of the test extract to that
12、of thecalibration curve would equal one.3.1.6 extractantan aqueous buffer of pH 7.4 6 0.2 usedfor the extraction process.3.1.7 initial settingthe instrument setting to which thespectrophotometer is adjusted with the reference solution.3.1.8 interferentany substance that results in a false posi-tive
13、or negative measurement in the analytical test method.1This test method is under the jurisdiction of ASTM Committee D11 on Rubberand is the direct responsibility of Subcommittee D11.40 on Consumer RubberProducts.Current edition approved July 1,2015.Published September 2015.Originallyapproved in 1995
14、.Last previous edition approved in 2010 as D5712 10.DOI:10.1520/D5712-15.2For 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 w
15、ebsite.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 3.1.9 latex proteinaqueous extractable proteins and poly-peptides occurring in latex and its products.3.1.10 limit of detection(LOD)the lowest protein concen-tration that can be measu
16、red and be statistically different fromthe blank.The LOD is expressed as 3.3 standard error of they-intercept of the calibration regression line divided by theslope of the calibration line.3.1.11 limit of quantitation(LOQ)the lowest protein con-centration that can be measured to produce quantitativelymeaningful results with acceptable precision and accuracy.TheLOQ is expressed as 10 standard error of the y-intercept of thecalibration regression line divided by the slope of the calibra-tion line.
