1、Designation: D 2379 09Standard 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 () 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
3、 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
4、 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 the
5、responsibility 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 Wate
6、rD 2380 Test Method for Methanol Content of Formalde-hyde SolutionsE29 Practice for Using Significant Digits in Test Data toDetermine Conformance with SpecificationsE 200 Practice for Preparation, Standardization, and Stor-age of Standard and Reagent Solutions for ChemicalAnalysis3. Summary of Test
7、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 Bur
8、et, 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
9、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
10、of WaterReference to water shall be understoodto mean reagent water conforming to Type IV or better ofSpecification 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 Hydroxide, Standard Sol
11、ution (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 suppliersMaterial Safe
12、ty 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 Pain
13、tand 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 D 2379 04.
14、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,
15、 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.
16、 (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 flask, add 3 or 4 drops of
17、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 titrateto a blue end point.9.
18、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 acid,S = millilitres of
19、 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 within 0.002 % absolutear
20、e 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 deg
21、reesof 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 beconsidered suspect if t
22、hey 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 interlaboratorystudy in
23、volving 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 formaldeh
24、yde; formic acidSUMMARY OF CHANGESCommittee D01.35 has identified the location of selected changes to this standard since the last issue(D 2379 - 04) that may impact the use of this standard. (Approved June 1, 2009.)(1) Modified 6.2.ASTM International takes no position respecting the validity of any
25、 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 such rights, are entirely their own responsibility.This standard is subject to revi
26、sion 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 either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your
27、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 hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyri
28、ghted 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).D2379092
