1、Designation: D 2379 04Standard Test Method forAcidity of Formaldehyde Solutions1This standard is issued under the fixed designation D 2379; 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 pare
2、ntheses indicates the year of last reapproval. Asuperscript epsilon (e) 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 The values stated in SI units are to b
3、e regarded as thestandard. The values given in parentheses are for informationonly.1.3 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
4、 used in expressing thespecification limit, in accordance with the rounding-off methodof Practice E 29.1.4 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
5、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:2D 1193 Specification for Reagent W
6、aterD 2380 Test Method for Methanol Content of Formalde-hyde SolutionsE 200 Practice for Preparation, Standardization, and Stor-age of Standard and Reagent Solutions for ChemicalAnalysisE 29 Practice for Using Significant Digits in Test Data toDetermine Conformance with Specifications3. Summary of T
7、est 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
8、 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 specificati
9、ons 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 Pur
10、ity of WaterUnless otherwise indicated, referencesto water shall be understood to mean reagent water conformingto Type IV of Specification D 1193.6.3 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
11、Hydroxide, Standard Solution (0.1 N)Prepareand standardize 0.1 N sodium hydroxide (NaOH) solution asdescribed in Practice E 200.7. Hazards7.1 Formaldehyde and formaldehyde solutions are hazard-ous and exposure to them should be minimized to avoid acuteeffects and possible sensitization. Consult your
12、 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 AST
13、M 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, 2004. Published June 2004. Originallyapproved in 1965. Last previous edition approve
14、d in 1999 as D 2379 99.2For 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
15、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. Pharmac
16、opeial Convention, Inc. (USPC), Rockville,MD.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.8. Procedure8.1 Measure 50 mL of the sample into a 250-mL Erlenm-eyer flas
17、k, 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 E 200, and titrate
18、to a blue end point.9. Calculation9.1 Calculate the percent of formic acid as follows:Formic acid, weight % 5 V 3 N 3 0.046!/S 3 D!# 3 100 (1)where:V = millilitres of NaOH solution, required for titrationof the specimen,N = normality of the NaOH solution,0.046 = the milliequivalent weight of formic
19、acid,S = millilitres of sample used, andD = specific gravity of sample.The value of D from Test Method D 2380, 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 wi
20、thin 0.002 % absoluteare 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 0.0
21、031 % absolute at 9 degreesof 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 of dupli-cates, obtained by the same analyst on different days should be
22、considered suspect if they differ by more than 0.002 %absolute.11.1.2 ReproducibilityTwo results, each the mean of du-plicates, obtained by analysis in different laboratories, shouldbe considered suspect if they differ by more than 0.010 %absolute.NOTE 1The above precision estimates are based on an
23、interlaboratorystudy involving 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.
24、 Keywords12.1 formaldehyde; formic acidSUMMARY OF CHANGESSubcommittee D01.35 has identified the location of selected changes to this standard since the last issue(D 2379 99) that may impact the use of this standard.(1) Added reference to Practice E 29 in 1.3 of the Scopesection.(2) Added Practice E
25、29 to the list in 2.1 of the ReferencedDocuments section.ASTM 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 paten
26、t rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited eithe
27、r for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair he
28、aring you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).D2379042
