1、Designation: D 5910 05Standard Test Method forDetermination of Free Formaldehyde in Emulsion Polymersby Liquid Chromatography1This standard is issued under the fixed designation D 5910; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revisio
2、n, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) 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 polymers without
3、 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 established working rang
4、e 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 There are no k
5、nown 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.1.4 The values
6、 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 appro-priate safet
7、y and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 1193 Specification for Reagent WaterD 2194 Test Method for Concentration of FormaldehydeSolutionsE 180 Practice for Determining the Precision of ASTMMethods for
8、 Analysis and Testing of Industrial and Spe-cialty ChemicalsE 682 Practice for Liquid Chromatography Terms and Re-lationships3. Summary of Test Method3.1 The aqueous phase of an emulsion polymer is dilutedand chromatographed on a reversed-phase octadecyl silane(ODS) column using an aqueous mobile ph
9、ase 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 reagent (Nash Reagent). The conce
10、ntrationof 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 is necessary to make the det
11、erminationwithout 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 very selective for formaldehyde.
12、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, glyoxylic acid and propional
13、dehyde. 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 is the direct responsibility o
14、fSubcommittee D01.33 on Polymers and Resins.Current edition approved Oct. 1, 2005. Published January 2006. Originallyapproved in 1996. Last previous edition approved in 1996 as D 5910 96 whichwas withdrawn December 2004 and reinstated in October 2005.2For referenced ASTM standards, visit the ASTM we
15、bsite, 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.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United St
16、ates.5.2 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 peak insubsequent runs.6. Apparatus6.1 Liquid ChromatographAny liquid chroma
17、tographicinstrument 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 2The UV-Vis detector may incorporate either a tungsten lampor a deuterium
18、 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 Coil3that can be heated to 95C and contains a staticmixing tee.4,56.3 Chromatographic ColumnColumn shoul
19、d 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.6.5 Data System, that can collect data at 1 point/s from a1-V output det
20、ector.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.66.8 CentrifugeAny high speed centrifuge that can gener-ate 50 000 r/min (274 980 g) or greater (Procedur
21、e 2).6.9 CentrifugeAny centrifuge that can generate 1000r/min or greater (Procedure 3).7. Configuration of Liquid Chromatograph7.1 An in-line check valve7is placed between the pump andthe injector. The guard and analytical columns are connected tothe injector. The outlet of the analytical column is
22、connected tothe mixing tee as described in 8.1.8. Configuration of Post-Column Reactor (PCR)8.1 The post-column reagent passes through a pulsedamp-ener8and an in-line check valve7prior to the mixing tee. Theoutlet of the analytical column is connected to one side of amixing tee. The reaction coil is
23、 connected to the outlet of themixing tee. Stainless steel tubing with 0.25-mm inside diam-eter is used to make the connections. Tubing lengths should bekept to a minimum. The mixing tee and reaction coil are placedinside a 95C oven. A 40 cm-length of 0.25-mm insidediameter stainless steel tubing is
24、 connected to the outlet of thereaction coil and is placed in an ambient-temperature stirredwater bath. (This configuration acts as a heat exchanger.) Theexit of the stainless steel tubing is connected to the UV/Visdetector. Fig. 1 shows a schematic of the system.9. Reagents and Materials9.1 Purity
25、of ReagentsReagent grade chemicals shall beused with this test method. Unless otherwise indicated, it is3Knitted capillary delay tube such as Supelco No. 5-9206 available fromSupelco Inc., Supelco Park, Bellefonte, PA 16823 has been found satisfactory forthis purpose.4Static mixing tee, available fr
26、om 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.5Timberline RDR-1, available from Alltech Associates, Inc., 2051 WaukeganRd., Deerfield, IL 60015, with two 0.4-mL serpentine reaction coils in series
27、, hasbeen found to be satisfactory for this purpose.6Filter such as Anotop 25 Plus Syringe Filter, 0.1 m, Catalog No. 2270,available from Alltech Assoc., has been found to be satisfactory for this purpose.7In-line check valve CV-3001 and U-469, Catalog No. 2270, from UpchurchScientific has been foun
28、d to be satisfactory for this purpose.8Pulse dampener, SSI LO, Catalog No. 20-0218, available from Alltech Assoc.,has been found to be satisfactory for this purpose.FIG. 1 Schematic of Liquid Chromatograph and Post-ColumnReaction SystemsD5910052intended that all reagents shall conform to the specifi
29、cation ofthe Committee onAnalytical Reagents of theAmerican Chemi-cal Society, where such specifications are available.9Othergrades may be used, provided it is first ascertained that thereagent is of sufficiently high purity to permit its use withoutlessening the accuracy of the determination.9.2 Wa
30、terUnless otherwise indicated, references to watershall be understood to mean reagent water minimally conform-ing to Type II of Specification D 1193, or distilled deionizedwater. High-performance liquid chromatography (HPLC)grade water from chromatography suppliers is also acceptable.9.3 Acetic Acid
31、, glacial (CH3CO2H).9.4 Ammonium Acetate(CH3CO2NH4).9.5 Formaldehyde, 37 % (HCHO).9.6 2,4-Pentanedione, 99 % (CH3COCH2COCH3).109.7 Phosphoric Acid Solution (0.1 N)Dissolve 2.3 mL ofphosphoric acid 85 % (H3PO4) in water and dilute to 1 L withwater.9.8 Potassium Ferrocyanide Trihydrate Solution (36 g/
32、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 heptahydrate, 99.9 %(ZnSO47H2O) in water and dilute to 1 L with water.9.10 Sodium Hydr
33、oxide (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 ammonium acetate to a 1-L amberbottle11that contains a stir bar. Add 600 mL of wa
34、ter 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 the bottle and mix thoroughly (45 min of mixing issuggested).NOTE 32,4-Pentane
35、dione 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 should be protected from light.10.1.4 Degas the post-column reagent with a helium s
36、parge.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, dibasic hascompletely dissolved.10.2.2 Adjust the pH of the solution to 7.0 wit
37、h 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 used in the sample preparation (see section 12.2.3).10.3 Sample Diluent:10.3.1 Tra
38、nsfer 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 preparation requires a pHadjustment. Before that step can occur the pH of the em
39、ulsionpolymers 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 mentioned in 10.3.2.10.3.4 Adjust the pH of the diluents to 0.1 pH unit usinge
40、ither 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 until a stable base line isobtained on the data system.Column temperature: ambient
41、Mobile 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 byinjecting 50 L of a 10 ppm formaldehyde standard solution. Atypical chromatogram of a 1
42、0-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 of peak asymmetry should be performed inaccordance with Practice E 682. A typi
43、cal 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. Calibration and Standardization12.1 Prepare a 25-mL stock solution of formald
44、ehyde 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 Test MethodD 2194.9Reagent Chemicals, American Chemical Society Specifications,
45、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.
46、(USPC), Rockville,MD.102,4-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.11A bottle that filters out ultraviolet and visible light is suitable.D591005312.2 Calculat
47、e the formaldehyde concentration of the stocksolution according to the following equation:Formaldehyde, ppm 5 A 3 103! / B (1)where:A = weight of formaldehyde, mg (corrected for activeingredient), andB = weight of formaldehyde and diluent, g.12.3 Prepare calibration standards ranging from 0.05 to 15
48、ppm 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 notin use. Prepare the stock and standard solutions weekly.12.5 The area under the fo
49、rmaldehyde 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 notexceeded the linear response range of any part of the system;that is, column, detector, inte
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