ASTM_D_2379_-_09.pdf

Designation:D237909Standard Test Method forAcidity of Formaldehyde Solutions1This standard is issued under the fixed designation D2379;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 the acidityof commercially available formaldehyde solutions.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 the user of 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 7.2.Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent WaterD2380 Test Method for Methanol Content of FormaldehydeSolutionsE29 Practice for Using Significant Digits in Test Data toDetermine Conformance with SpecificationsE200 Practice for Preparation,Standardization,and Storageof Standard and Reagent Solutions for Chemical Analysis3.Summary of Test Method3.1 A specimen is titrated with standard alkali to thebromthymol blue end point.4.Significance and Use4.1 This test method provides a measurement of acidity(asformic acid)in formaldehyde solutions.The results of thesemeasurements can be used for specification acceptance.5.Apparatus5.1 Buret,25-mL,calibrated in 0.1-mL divisions.A TFE-fluorocarbon resin stopcock is suitable for this purpose.6.Reagents and Materials6.1 Purity of ReagentsReagent grade chemicals shall beused in all tests.Unless otherwise indicated,it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available.3Other grades may beused,provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.6.2 Purity of WaterReference to water shall be understoodto mean reagent water conforming to Type IV or better ofSpecification D1193.6.3 Bromthymol Blue Indicator Solution(1.0 g/L)Dissolve 0.1 g of the water-soluble form of bromthymol blueindicator powder in 100 mL of water.6.4 Sodium Hydroxide,Standard Solution(0.1 N)Prepareand standardize 0.1 N sodium hydroxide(NaOH)solution asdescribed in Practice E200.7.Hazards7.1 Formaldehyde and formaldehyde solutions are hazard-ous and exposure to them should be minimized to avoid acuteeffects and possible sensitization.Consult your suppliersMaterial Safety Data Sheet for specific hazard information.7.2 Sodium hydroxide solutions are corrosive and hazard-ous.Exercise steps to prevent contact with the skin or eyes.Consult suppliers Material Safety Data Sheet for specifichazard.1This 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 1,2009.Published June 2009.Originallyapproved in 1965.Last previous edition approved in 2004 as D2379 04.DOI:10.1520/D2379-09.2For 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 website.3Reagent Chemicals,American Chemical Society Specifications,AmericanChemical Society,Washington,DC.For suggestions on the testing of reagents notlisted by the American Chemical Society,see Analar Standards for LaboratoryChemicals,BDH Ltd.,Poole,Dorset,U.K.,and the United States Pharmacopeiaand National Formulary,U.S.Pharmacopeial Convention,Inc.(USPC),Rockville,MD.*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 8.Procedure8.1 Measure 50 mL of the sample into a 250-mL Erlen-meyer flask,add 3 or 4 drops of bromthymol blue indicatorsolution,and titrate with 0.1 N NaOH solution to a blue endpoint.8.2 If good laboratory practice dictates that the concentra-tion of NaOH be adjusted as a result of higher or lower acidlevels,then adjust as necessary using Practice E200,and titrat