1、Designation: D5910 05 (Reapproved 2012)Standard Test Method forDetermination of Free Formaldehyde in Emulsion Polymersby Liquid Chromatography1This standard is issued under the fixed designation D5910; the number immediately following the designation indicates the year oforiginal adoption or, in the
2、 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. Scope1.1 This test method is used for the determination of freeformaldehyde (HCHO) in emulsion p
3、olymers without upset-ting existing formaldehyde equilibria. The procedure has beenevaluated using acrylic, acrylonitrile-butadiene, carboxylatedstyrene-butadiene and polyvinyl acetate emulsion polymers.This test method may also be applicable for emulsion polymersof other compositions. The establish
4、ed working range of thistest method is from 0.05 to 15 ppm formaldehyde. Emulsionpolymers must be diluted to meet the working range.1.2 This test method minimizes changes in free formalde-hyde concentration that can result from changes in the physicalor chemical properties of an emulsion polymer.1.3
5、 There are no known limitations to this test method whenused in the manner described. The emulsion polymer testspecimen must be prepared with a diluent that has a pH similarto that of the emulsion. Use of an inappropriate pH may upsetformaldehyde equilibria and result in incorrect formaldehydelevels
6、.1.4 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.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 app
7、ro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1193 Specification for Reagent WaterD2194 Test Method for Concentration of FormaldehydeSolutionsE180 Practice for Determining the Precision of AST
8、MMethods for Analysis and Testing of Industrial and Spe-cialty Chemicals (Withdrawn 2009)3E682 Practice for Liquid Chromatography Terms and Rela-tionships3. Summary of Test Method3.1 The aqueous phase of an emulsion polymer is dilutedand chromatographed on a reversed-phase octadecyl silane(ODS) colu
9、mn using an aqueous mobile phase and a visible-light detector at 410 nm. Formaldehyde is separated from otherspecies in the matrix on a chromatographic column. Thedetection system includes a post-column reactor that producesa lutidine derivative when formaldehyde reacts with the2,4-pentanedione reag
10、ent (Nash Reagent). The concentrationof free formaldehyde in emulsion polymers is determined usingpeak areas from the standard and sample chromatograms. Thistest method is specific for formaldehyde.4. Significance and Use4.1 With the need to calculate free formaldehyde levels inemulsion polymers, it
11、 is necessary to make the determinationwithout upsetting any equilibria that might generate or depleteformaldehyde. This test method provides a means for deter-mining ppm levels of free formaldehyde in emulsion polymerswithout upsetting existing equilibria.5. Interferences5.1 This test method is ver
12、y selective for formaldehyde.Potential interferants are either chromatographically separatedfrom formaldehyde or do not react with the post-columnreagent.NOTE 1The following species were identified as possible interfer-ences for the method: acetaldehyde, acetone, benzaldehyde, formamide,formic acid,
13、 glyoxylic acid and propionaldehyde. These species, whenchromatographed using this test method, did not interfere with theformaldehyde peak at the 1000 ppm level or lower.1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings, Materials, and Applications and i
14、s the direct responsibility ofSubcommittee D01.33 on Polymers and Resins.Current edition approved Nov. 1, 2012. Published November 2012. Originallyapproved in 1996. Last previous edition approved in 2005 as D5910 05. DOI:10.1520/D5910-05R12.2For referenced ASTM standards, visit the ASTM website, www
15、.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.3The last approved version of this historical standard is referenced onwww.astm.org.Copyright ASTM International, 100 Ba
16、rr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15.2 Because emulsion polymers vary in composition, themethod run time may need to be extended to allow for lateeluting compounds. Compounds that remain on the columnafter an analysis may interfere with the formaldehyde pea
17、k insubsequent runs.6. Apparatus6.1 Liquid ChromatographAny liquid chromatographicinstrument having an injection valve, a post-column reactor, a410-nm UV-Vis detector, and an isocratic solvent deliverysystem may be used. The solvent delivery system must delivera mobile phase flow of 0.6 mL/min.NOTE
18、2The UV-Vis detector may incorporate either a tungsten lampor a deuterium lamp with a second order visible filter that filters out lightbelow 400 nm.6.2 Post-Column ReactorAny post-column reactor thatcan deliver a reagent flow at 0.5 mL/min, contains a KnittedReaction Coil4that can be heated to 95C
19、and contains a staticmixing tee.5,66.3 Chromatographic ColumnColumn should be 250 by4.6 mm inside diameter packed with a reversed-phase pHstable C18, 5-m particles.6.4 Chromatographic Guard ColumnThe column shouldbe 10 by 4.6 mm inside diameter packed with a reversed-phasepH stable C18 5-m particles
20、.6.5 Data System, that can collect data at 1 point/s from a1-V output detector.6.6 Syringe100 L capacity.6.7 Sample FilterThe filter should consist of a 5-mLsample syringe and a 0.1-m-filter assembly to remove microparticulate matter from the prepared sample solution.76.8 CentrifugeAny high speed ce
21、ntrifuge that can gener-ate 50 000 r/min (274 980 g) or greater (Procedure 2).6.9 CentrifugeAny centrifuge that can generate 1000r/min or greater (Procedure 3).7. Configuration of Liquid Chromatograph7.1 An in-line check valve8is placed between the pump andthe injector. The guard and analytical colu
22、mns are connected tothe injector. The outlet of the analytical column is connected tothe mixing tee as described in 8.1.8. Configuration of Post-Column Reactor (PCR)8.1 The post-column reagent passes through apulsedampener9and an in-line check valve8prior to the mixingtee. The outlet of the analytic
23、al column is connected to one sideof a mixing tee. The reaction coil is connected to the outlet ofthe mixing tee. Stainless steel tubing with 0.25-mm insidediameter is used to make the connections. Tubing lengthsshould be kept to a minimum. The mixing tee and reaction coilare placed inside a 95C ove
24、n. A 40 cm-length of 0.25-mminside diameter stainless steel tubing is connected to the outletof the reaction coil and is placed in an ambient-temperaturestirred water bath. (This configuration acts as a heat ex-changer.) The exit of the stainless steel tubing is connected tothe UV/Vis detector. Fig.
25、 1 shows a schematic of the system.9. Reagents and Materials9.1 Purity of ReagentsReagent grade chemicals shall beused with this test method. Unless otherwise indicated, it isintended that all reagents shall conform to the specification of4Knitted capillary delay tube such as Supelco No. 5-9206 avai
26、lable fromSupelco Inc., Supelco Park, Bellefonte, PA 16823 has been found satisfactory forthis purpose.5Static mixing tee, available from Upchurch Scientific, 619 W. Oak St., P.O. Box1529, Oak Harbor, WA 98277-1529, Catalog No. U-466, has been found to besatisfactory for this purpose.6Timberline RDR
27、-1, available from Alltech Associates, Inc., 2051 WaukeganRd., Deerfield, IL 60015, with two 0.4-mL serpentine reaction coils in series, hasbeen found to be satisfactory for this purpose.7Filter such as Anotop 25 Plus Syringe Filter, 0.1 m, Catalog No. 2270,available from Alltech Assoc., has been fo
28、und to be satisfactory for this purpose.8In-line check valve CV-3001 and U-469, Catalog No. 2270, from UpchurchScientific has been found to be satisfactory for this purpose.9Pulse dampener, SSI LO, Catalog No. 20-0218, available from Alltech Assoc.,has been found to be satisfactory for this purpose.
29、FIG. 1 Schematic of Liquid Chromatograph and Post-ColumnReaction SystemsD5910 05 (2012)2the Committee onAnalytical Reagents of theAmerican Chemi-cal Society, where such specifications are available.10Othergrades may be used, provided it is first ascertained that thereagent is of sufficiently high pu
30、rity to permit its use withoutlessening the accuracy of the determination.9.2 WaterUnless otherwise indicated, references to watershall be understood to mean reagent water minimally conform-ing to Type II of Specification D1193, or distilled deionizedwater. High-performance liquid chromatography (HP
31、LC)grade water from chromatography suppliers is also acceptable.9.3 Acetic Acid, glacial (CH3CO2H).9.4 Ammonium Acetate(CH3CO2NH4).9.5 Formaldehyde, 37 % (HCHO).9.6 2,4-Pentanedione, 99 % (CH3COCH2COCH3).119.7 Phosphoric Acid Solution (0.1 N)Dissolve 2.3 mL ofphosphoric acid 85 % (H3PO4) in water an
32、d dilute to 1 L withwater.9.8 Potassium Ferrocyanide Trihydrate Solution (36 g/L)Carrez Solution IDissolve 26 g of potassium ferrocyanidetrihydrate, 99 % (K4Fe(CN)63H2O) in water and dilute to 1 Lwith water.9.9 Zinc Sulfate Heptahydrate (72 g/L) Carrez SolutionIIDissolve 72 g of zinc sulfate heptahy
33、drate, 99.9 %(ZnSO47H2O) in water and dilute to 1 L with water.9.10 Sodium Hydroxide (0.1 N)Dissolve8gofsodiumhydroxide 50 % (NaOH) in water and dilute to 1 L with water.9.11 Sodium Phosphate, dibasic, 98 % (Na2HPO4).10. Preparation10.1 Post-Column Reagent (Nash Reagent):10.1.1 Transfer 62.5 g of am
34、monium acetate to a 1-L amberbottle12that contains a stir bar. Add 600 mL of water to thebottle and mix on a stir plate until the ammonium acetate hascompleted dissolved.10.1.2 Pipet 7.5 mL of glacial acetic acid into the bottle.Pipet 5 mL of 2,4-pentanedione into the bottle. Add 387.5 mLof water to
35、 the bottle and mix thoroughly (45 min of mixing issuggested).NOTE 32,4-Pentanedione is light sensitive and should be protectedfrom light during use.NOTE 4The post-column reagent should be prepared weekly.10.1.3 Transfer the post-column reagent to the post-columnreactor reservoir. The reservoir shou
36、ld be protected from light.10.1.4 Degas the post-column reagent with a helium sparge.10.2 Mobile Phase and Standard Diluent:10.2.1 Transfer 1.78 g of sodium phosphate, dibasic to a 2-Lmobile phase reservoir that contains a stir bar.Add 2 L of waterand mix on a stir plate until the sodium phosphate,
37、dibasic hascompletely dissolved.10.2.2 Adjust the pH of the solution to 7.0 with 0.1 Nphosphoric acid.10.2.3 Degas the mobile phase with a helium sparge.NOTE 5Water may also be used as the mobile phase without theaddition of a buffer.Awater mobile phase should be used when the Carrezreagents are use
38、d in the sample preparation (see section 12.2.3).10.3 Sample Diluent:10.3.1 Transfer 0.89 g of sodium phosphate, dibasic to a 1-Lbottle that contains a stir bar. Add 1 L of water and mix on astir plate until the sodium phosphate, dibasic has completelydissolved.10.3.2 The final step of the diluent p
39、reparation requires a pHadjustment. Before that step can occur the pH of the emulsionpolymers must be measured to 0.1 pH unit. The emulsionpolymers must be diluted with a buffer that is 60.1 pH unit ofthe emulsion polymer.10.3.3 Divide the 1-L solution into the number of separatediluents required as
40、 mentioned in 10.3.2.10.3.4 Adjust the pH of the diluents to 0.1 pH unit usingeither 0.1 N NaOH or 0.1 N H3PO4.11. Operating Conditions for Analysis11.1 Adjust the liquid chromatograph in accordance withthe manufacturers directions and the following parameters.Allow the instrument to equilibrate unt
41、il a stable base line isobtained on the data system.Column temperature: ambientMobile phase: 6.3 mM Na2HPO4(pH = 7) or waterFlow rate: 0.6 mL/minInjection volume: 50 LPCR temperature: 95CPCR flow rate: 0.5 mL/minDetector: UV/Vis, 410 nm11.2 Determine whether the system is working properly byinjectin
42、g 50 L of a 10 ppm formaldehyde standard solution. Atypical chromatogram of a 10-ppm formaldehyde standardobtained under the conditions outlined in 11.1 is shown in Fig.2. Make sure that the peak asymmetry (Asat 10 % peak height)value for formaldehyde is within the range of 0.8 and 1.7.Determination
43、 of peak asymmetry should be performed inaccordance with Practice E682. A typical retention time forformaldehyde is 6 min.11.3 The run time for the analysis is 10 min. The run timemay have to be extended 20 to 30 min if late elutingcompounds interfere with the formaldehyde peak in subsequentruns.12.
44、 Calibration and Standardization12.1 Prepare a 25-mL stock solution of formaldehyde at the1.18 % (11 840 ppm) level by adding 0.8 g of formaldehyde(37 %) to 24.2 g standard diluent.NOTE 6Reagent grade formaldehyde is nominally 37 %. Perform theassay of the formaldehyde solution in accordance with Te
45、st MethodD2194.10Reagent 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 S
46、tates Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.112,4-Pentanedione (acetyl acetone), 99 %, available from Aldrich ChemicalCo., 2905 W. Hope Ave., Milwaukee, WI 53216, Catalog No. P775-4, has beenfound to be satisfactory for this method.12A bottle th
47、at filters out ultraviolet and visible light is suitable.D5910 05 (2012)312.2 Calculate the formaldehyde concentration of the stocksolution according to the following equation:Formaldehyde, ppm 5 A 3103!/B (1)where:A = weight of formaldehyde, mg (corrected for activeingredient), andB = weight of for
48、maldehyde and diluent, g.12.3 Prepare calibration standards ranging from 0.05 to 15ppm of formaldehyde in standard diluent.12.4 Inject 50 L of each standard solution and a reagentblank (standard diluent) into the liquid chromatograph.NOTE 7Store stock and standard solutions in a refrigerator when no
49、tin use. Prepare the stock and standard solutions weekly.12.5 The area under the formaldehyde peak in the chro-matogram is considered a quantitative measure of the corre-sponding compound.12.6 Measure the area of the formaldehyde peak by conven-tional means (Note 8). Prepare a calibration curve by plottingthe integrated peak area versus the concentration (ppm) offormaldehyde as in Fig. 3. The calibration must be done toensure that the entire chromatographic system is operatingproperly and that the concentration of formaldehyde has notexceed
