1、Designation: D2379 09 (Reapproved 2017)Standard 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.
2、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 the determination of the acidityof commercially available formaldehyde solutions.1.2 For purposes of determin
3、ing 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 v
4、alues 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 suppliersSafety Data Sheet.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It
5、is theresponsibility of the user of this standard to establish appro-priate safety, health, and environmental practices and deter-mine the applicability of regulatory limitations prior to use.Specific hazard statements are given in Section 7.1.6 This international standard was developed in accor-dan
6、ce with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards, Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Sta
7、ndards: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 f
8、or 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 speci
9、fication 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 reagen
10、ts 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 theac
11、curacy 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 wa
12、ter.6.4 Sodium Hydroxide, Standard Solution (0.1 N)Prepareand standardize 0.1 N sodium hydroxide (NaOH) solution asdescribed in Practice E200.1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings, Materials, and Applications and is the direct responsibility o
13、fSubcommittee D01.35 on Solvents, Plasticizers, and Chemical Intermediates.Current edition approved Dec. 1, 2017. Published December 2017. Originallyapproved in 1965. Last previous edition approved in 2009 as D2379 09. DOI:10.1520/D2379-09R17.2For referenced ASTM standards, visit the ASTM website, w
14、ww.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 suggestion
15、s 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.Copyright ASTM International, 100 B
16、arr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards, Guides and Reco
17、mmendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.17. Hazards7.1 Formaldehyde and formaldehyde solutions are hazard-ous and exposure to them should be minimized to avoid acuteeffects and possible sensitization. Consult your suppliersSafety Data Sheet for
18、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.8. Procedure8.1 Measure 50 mL of the sample into a 250-mL Erlen-meyer flask, add 3 or 4 dro
19、ps 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 titrateto a blue end poin
20、t.9. Calculation9.1 Calculate the percent of formic acid as follows:Formic acid, weight% 5 V 3 N 30.046!/S 3 D!# 3100 (1)where:V = millilitres of NaOH solution, required for titration ofthe specimen,N = normality of the NaOH solution,0.046 = the milliequivalent weight of formic acid,S = millilitres
21、of sample used, andD = specific gravity of sample.The value of D from Test Method D2380, may be used,although specific gravity estimated to the second decimal isadequate.10. Report10.1 Report the percent formic acid to the nearest 0.001 %.Duplicate determinations which agree within 0.002 % absolutea
22、re acceptable for averaging (95 % confidence level).11. Precision and Bias11.1 In an interlaboratory study of this test method, thewithin-laboratory standard deviation was found to be 0.0007 %absolute at 60 degrees of freedom, and the between-laboratories standard deviation 0.0031 % absolute at 9 de
23、greesof freedom. Based on these standard deviations, the followingcriteria should be used for judging the acceptability of resultsat the 95 % confidence level:11.1.1 RepeatabilityTwo results, each the mean ofduplicates, obtained by the same analyst on different daysshould be considered suspect if th
24、ey differ by more than0.002 % absolute.11.1.2 ReproducibilityTwo results, each the mean ofduplicates, obtained by analysis in different laboratories,should be considered suspect if they differ by more than0.010 % absolute.NOTE 1The above precision estimates are based on an interlaboratorystudy invol
25、ving ten laboratories using three samples with two analystsperforming duplicate runs on each of two days. The mean level of theacidity value of the samples studied was 0.02 %.11.2 BiasBias of this test method has not been determinedbecause primary standards do not exist.12. Keywords12.1 formaldehyde
26、; formic acidASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of suc
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