1、Designation: D 6191 97 (Reapproved 2008)1Standard Test Method forMeasurement of Evolved Formaldehyde from WaterReducible Air-Dry Coatings1This standard is issued under the fixed designation D 6191; the number immediately following the designation indicates the year oforiginal adoption or, in the cas
2、e 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.1NOTEThe precaution note was moved into subsection 6.2 editorially in November 2008.1. Scope1.1 This te
3、st method may be used to measure the amount offormaldehyde evolved from air-dry water reducible coatingsutilizing latices, resin emulsions, or water reducible alkyds.The results may be used to define the “free” formaldehydeevolved from a sample under controlled laboratory conditions.1.2 This standar
4、d 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.2. Referenced Documents2.1 ASTM
5、 Standards:2D 2194 Test Method for Concentration of FormaldehydeSolutions3. Summary of Test Method3.1 A sample of water reducible coating is placed on thewalls of a test tube with a drawdown rod and purged withnitrogen. The evolved formaldehyde is collected in deionizedwater with tandem impingers an
6、d measured colorimetricallyusing acetylacetone at 412 nm.4. Significance and Use4.1 This test method measures the amount of formaldehydethat is released from a coating under laboratory conditions. Theamount of formaldehyde available for release from a coatingmay vary depending on composition, and ma
7、y decrease as thesample ages.4.2 This test method may be used for typical air dried paintswhere water is the major volatile material. The useful range isestimated to be from 10 ppm to 1000 ppm formaldehyde in thesample.4.3 Significant amounts of other volatile aldehydes, such asacetaldehyde, are rep
8、orted to cause an interference with thedetermination of formaldehyde. This limitation is not expectedto cause a problem for most common water reducible coatings.4.4 Samples containing organic solvents as the major vola-tile component have not been evaluated and are not expected tobe compatible with
9、this test method.5. Apparatus5.1 Formaldehyde Collection Apparatus, assembled using aflowmeter to control the nitrogen flow at ; 1.0 L/min, a 25 by200 mm outside diameter long glass test tube, and two 30-mLmidget impingers. Connections are made with glass tubesthrough a No. 4 two-hole rubber stopper
10、 and clear flexibletubing (see Fig. 1).5.2 Drawdown Bar, stainless steel No. 22 wire-wound6.4-mm rod.5.3 Glass Sample Bottles,(;2 oz), capable of holding30-mL solution.5.4 Spectrophotometer, capable of measuring the absor-bance of solutions at 412 nm with a minimum sample light pathof 10 mm.1This te
11、st method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings, Materials, and Applications and is the direct responsibility ofSubcommittee D01.21 on Chemical Analysis of Paints and Paint Materials.Current edition approved Nov. 1, 2008. Published November 2008. Originallyappr
12、oved in 1997. Last previous edition approved in 2003 as D 6191 97 (2003).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 A
13、STM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6. Reagents6.1 Acetylacetone SolutionDissolve 150 6 0.1 g ammo-nium acetate in ;600 mL deionized water in a 1-L volumetricflask. Add 3.0-mL glacial acetic acid and 2.0-mL ac
14、etylacetone(2,4 pentanedione) and dilute to volume.6.2 Formaldehyde SolutionUse 37 % in methanol/water,commercial stock standard solution. If a commercially cali-brated 37 % standard solution is not being used, the concen-tration of formaldehyde may determined in accordance withTest Method D 2194. T
15、hen, the actual concentrations of theworking calibrations standards are to be calculated using themeasured value. (WarningFormaldehyde, acetylacetone,and the other reagents used in this test method are toxic orhazardous. Exposure to these materials should be minimized.Consult the suppliers Material
16、Safety Data Sheet for specifichazard information.)6.3 Formaldehyde Calibration StandardsPrepare a 100-ppm stock solution by diluting 25 uLof the 37 % formaldehydesolution to 100 mL with deionized water. Dilute this interme-diate stock solution to prepare at least 5 calibration standards.Pipeting 0.5
17、, 3, 5, 7 and 10 mL aliquots of the stock solutioninto 100-mL volumetric flasks and diluting with deionizedwater will prepare calibration standards of 0.5, 3, 5, 7 and 10ppm formaldehyde.7. Calibration7.1 Prepare a series of at least 5 standards (6.3) plus a blankby adding 5 mL of the formaldehyde c
18、alibration standards or 5mL deionized water into test tubes. Process the standard alongwith the samples as described in 8.5 to 8.6.7.2 Construct a calibration curve by plotting the absorbanceof the calibration standards versus concentration of formalde-hyde (ppm). Prepare a new calibration curve wit
19、h every batchof samples being analyzed.8. Procedure8.1 Assemble the collection apparatus as shown in Fig. 1.The ;1.0 L/min. flow rate should be determined by timing theflow with a bubble tube. If the impingers are not accuratelygraduated, pipet 15-mL deionized water into the impingertubes and mark t
20、he level for future reference.8.2 Place about 1 to 1.5 g of the liquid sample into a taredtest tube and evenly spread the sample on the walls with a No.22 drawdown rod. The bottom couple of inches of the test tubewill not be coated and the top ;12 in. of the tube should bewiped free of coating with
21、a paper towel to avoid having painton the stopper. Quickly weigh the coated test tube and recordthe weight of the liquid sample.8.3 Without delay, connect the test tube to the apparatuscontaining 15-mL deionized water in each impinger and purgewith nitrogen at ;1.0 L/min for 2 h.8.4 With the nitroge
22、n flowing, remove the impinger tubefrom the No. 2 impinger. If the sampling liquid is less than theoriginal 15 mL volume, restore the volume to 15 mL whilerinsing the impinger tube with deionized water. Disconnect theNo. 1 impinger in the series and rinse the impinger tube withdeionized water in ord
23、er to restore the volume to 15 mL. Pourthe No. 1 impinger solution, which should contain most of theformaldehyde, into a ;2-oz. bottle. Use the No. 2 impingersolution to wash the No. 1 impinger tube and mix the combinedsolutions in the sealed bottle.8.5 Pipet 5 mL of the impinger solution (or a dilu
24、tedsolution) into a ;20-mL glass test tube and add 5 mL of theacetylacetone solution. Mix the prepared test solutions and heatthe test tubes in a 40 6 0.5C water bath for 30 min.8.6 Remove the test tubes from the water bath and let standfor 30 min to cool. Measure the absorbance at 412 nm with aspec
25、trophotometer using a 1-cm cell and deionized water as thereference.8.7 From the calibration curve, determine the concentrationof the combined impinger solution. If the concentration of thetest solution is greater that the highest standard, make appro-priate dilutions of the impinger solution and re
26、peat 8.5 to 8.6with freshly prepared standards. Some analysts may prefer toprepare dilutions initially rather than repeat the standardpreparation process.9. Calculation9.1 Calculate the amount of formaldehyde that is evolvedfrom the sample as follows:ppm Formaldehyde 5C 3 30 3 DW(1)where:C = concent
27、ration from calibration curve (8.7),30 = volume (mL) of water in the impingers,D = dilution factor if diluted, andW = sample weight, g.10. Report10.1 Report the concentration of evolved formaldehydefrom the sample as parts per million rounded to two significantdigits.11. Precision and Bias11.1 Repea
28、tabilityTo be determined.11.2 ReproducibilityTo be determined.11.3 BiasThe bias can not be determined since no validstable reference material is available.12. Keywords12.1 air-dry water reducible coatings; evolvedformaldehydeFIG. 1 Formaldehyde Collection ApparatusD 6191 97 (2008)12ASTM Internationa
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32、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).D 6191 97 (2008)13
