ASTM E2313-2008 Standard Test Method for Aldehydes in Mono- Di- and Triethylene Glycol (Spectrophotometric Method)《单乙二醇中醛的测试方法(光谱光度测量法)》.pdf

1、Designation: E 2313 08Standard Test Method forAldehydes in Mono-, Di-, and Triethylene Glycol(Spectrophotometric Method)1This standard is issued under the fixed designation E 2313; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, th

2、e 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. Scope*1.1 This test method describes the spectrophotometric de-termination of total aldehyde carbonyl content in the

3、 range of0.5 to 50 mg/kg (as acetaldehyde) or 0.3 to 35 mg/kg (asformaldehyde) in mono-, di-, and triethylene glycol (MEG,DEG and TEG). Alkoxyalcohols (hemiacetals), if present, areco-determined, whereas dialkoxyalkanes (acetals), if present,are not. The results provide a measure of the purity of th

4、esample with respect to total aldehyde carbonyl content.1.2 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.3 Review the current material Safety Data Sheets (MSDS)for detailed information concerning toxicity, first aid proce-d

5、ures and safety precautions.1.4 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 safety and health practices and determine the applica-bility of regulatory limitations

6、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 Analysis and Testing of Industrial and Spe-cialty ChemicalsE 275 Practice for Des

7、cribing and Measuring Performanceof Ultraviolet, Visible, and Near-Infrared Spectrophotom-etersE 288 Specification for Laboratory Glass Volumetric FlasksE 300 Practice for Sampling Industrial ChemicalsE 969 Specification for Glass Volumetric (Transfer) Pipets2.2 Other Document:Manufacturers Instruct

8、ion Manual of Spectrophotometer3. Summary of Test Method3.1 The total aldehyde carbonyl content of the sample isdetermined spectrophotometrically. The aldehydes present arereacted with excess 3-methyl-2-benzothiazolinone hydrazone(MBTH) to form azines. An aqueous solution of iron (III)chloride is ad

9、ded, causing the oxidation of the excess MBTH toa reactive cation, which reacts with the previously formedazines producing bluish-green cations. Acetone or methanol isadded to stop the oxidation reaction, to mask the excess MBTHand to obtain a clear solution. The absorbance of the testsolution is me

10、asured spectrophotometrically at 635 nm. Theamount of aldehyde present in the test solution is derived froma previously prepared calibration graph. The aldehyde contentof the sample, expressed as either acetaldehyde or formalde-hyde, is calculated from the data obtained.4. Significance and Use4.1 Kn

11、owledge of the aldehyde content of Monoethyleneglycol is required to establish whether the product meets therequirements of its quality specifications.5. Apparatus5.1 Spectrophotometer, suitable for measurement at a wave-length of 635 nm, provided with cells with a pathlength of 10mm.NOTE 1Further i

12、nformation on spectrophotometers can be obtainedfrom Practice E 275.5.2 Analytical Balance, readable to 0.1 mg, calibrated.Calibrate and verify at regular intervals.5.3 Stopwatch, measuring accuracy 61 s or better. Calibrateor verify at regular intervals.5.4 Apparatus, as described in Test Method D

13、2194.5.4.1 Buret, calibrated, 100-mL, with a 50 or 75-mL reser-voir on top of a lower portion calibrated in 0.1-mL divisions.APTFE-fluorocarbon resin stopcock is suitable for this purpose.5.4.2 Erlenmeyer Flask, approximately 5-mL capacity.5.4.3 Vials, specimen, short, style, approximately 5-mLcapac

14、ity.1This test method is under the jurisdiction of ASTM Committee E15 onIndustrial and Specialty Chemicals and is the direct responsibility of SubcommitteeE15.02 on Product Standards.Current edition approved April 1, 2008. Published May 2008. Originallyapproved in 2003. Last previous edition approve

15、d in 2004 as E 2313 04.2For 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.1*A Summary of Changes section appears

16、 at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.5 Glassware:NOTE 2In cases where volumetric glassware is to be used, it shallconform to Grade (or Class) A specifications as described in, for example,Spec

17、ification E 288 for volumetric flasks, or Specification E 969 forone-mark pipettes.5.5.1 Graduated Pipettes, capable of quantitatively transfer-ring between 0.5 and 5 mL, or5.5.2 Volumetric Pipette, 0.5, 1.0, 2.0, 3.0, 4.0, 5.0 mL.5.5.3 Volumetric Pipettes,25mL.5.5.4 Volumetric Flasks, 100 mL, 1 L.5

18、.5.5 Brown Bottle, 1 L, with screw cap, for storage.6. Reagents6.1 Purity of ReagentsUnless otherwise indicated, it isintended that all reagents shall conform to the specifications ofthe committee on Analytical Reagents of the American Chemi-cal Society where such specifications are available.3Other

19、grades 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.6.1.1 Acetone (2-propanone), A.R. minimum purity99.99 % (V/V). (WarningAcetone is highly flammable.Keep container in a well-ventila

20、ted place. Keep away fromsources of ignition. Do not breathe vapor. Take precautionarymeasures against static discharges).6.1.2 Formaldehyde, A.R., 36 to 40 % mass formaldehydesolution (Formalin). (WarningFormaldehyde is toxic byinhalation, in contact with skin and if swallowed. Causesburns. Possibl

21、e risks of irreversible effects. May cause sensi-tization by skin contact. In case of contact with eyes, rinseimmediately with plenty of water and seek medical advice.Wear suitable protective clothing, gloves and eye/face protec-tion. In case of accident or if you feel unwell, seek medicaladvice imm

22、ediately. Use only in well ventilated areas.)6.1.3 Hydrochloric Acid, A.R., concentrated 36 % mass.(WarningHydrochloric Acid is toxic by inhalation. Causessevere burns. Keep container in a well-ventilated place. In caseof contact with eyes, rinse immediately with plenty of waterand seek medical advi

23、ce. Wear suitable protective clothing,gloves and eye/face protection. In case of accident or if youfeel unwell, seek medical advice immediately.)6.1.4 Iron (lll) Chloride, (FeCl36H2O), A.R. (WarningIron (III) Chloride causes burns. Avoid contact with skin andeyes. In case of contact with eyes, rinse

24、 immediately withplenty of water and seek medical advice. Take off immediatelyall contaminated clothing. Wear eye/face protection. If swal-lowed, seek medical advice immediately and show the con-tainer or label.)6.1.5 Methanol, A.R. minimum purity 99.99 % (V/V).(WarningMethanol is highly flammable.

25、Toxic by inhalationand ingestion. Keep container in a well-ventilated place. Keepcontainer tightly closed. Keep away from sources of ignition.Avoid contact with skin. In case of accident or if you feelunwell, seek medical advice immediately (show the labelwhere possible).6.1.6 3-Methyl-2-Benzothiazo

26、linone Hydrazone Hydrochlo-ride (MBTH). (WarningMBTH is toxic if swallowed. Irri-tating to eyes. Keep locked up. Avoid contact with skin andeyes. In case of contact with eyes, rinse immediately withplenty of water and seek medical advice. This material and itscontainer must be disposed of in a safe

27、way. Wear suitableprotective clothing. In case of accident or if you feel unwell,seek medical advice immediately. If swallowed, seek medicaladvice immediately and show the container or label.)6.2 Water, reagent water conforming to Type IV of Speci-fication D 1193.6.3 Solutions:6.3.1 Standard Formald

28、ehyde Solution, 8.0 g/mL, aque-ous. Determine the exact concentration (c1) of an A.R. 36 to40 % mass formaldehyde solution (WarningSee 6.1.2) ac-cording to Test Method D 2194, expressing the result in g/100mL. Weigh approximately 2.0 to 2.2 g (m1) of the formalde-hyde solution to the nearest 0.1 mg,

29、 into a 100-mL volumetricflask. Make up to the mark with water and mix thoroughly.Pipette 1.0 mL of this solution into a 1-L volumetric flask.Make up to the mark with water and mix thoroughly. Transferthis solution to a brown bottle with screw cap. Calculate theexact formaldehyde content of this sol

30、ution (c2), in g/mL, bymeans of the following equation:c2, g/mL 5m13 c110(1)where:c1= concentration of concentrated formaldehyde solutionused, g/100 mL, andm1= mass of concentrated formaldehyde solution taken, g.The concentrated and diluted formaldehyde solutions arestable in excess of six months if

31、 stored at room temperature.Do not store in a refrigerator. Prepare fresh solutions every sixmonths.6.3.2 Hydrochloric Acid, 50 %(V/V). Dilute one volume ofA.R. concentrated hydrochloric acid (WarningSee 6.1.3)with one volume of water.6.3.3 Iron (III) Chloride Solution, 0.3 % mass, aqueous.Dissolve5

32、gofA.R. iron (III) chloride. 6H2O(WarningSee6.1.4) in water, adding 1 or 2 drops of A.R. concentratedhydrochloric acid to stabilize solution (WarningSee 6.1.3)and dilute to 1 L with water. Prepare a fresh solution daily6.3.4 Methyl-2-benzothiazolone Hydrazone Solution(MBTH solution), 0.4 % mass, aqu

33、eous. Dissolve 400 6 1mgof MBTH hydrochloride (WarningSee 6.1.6) in water in a100-mL volumetric flask. Make up to the mark and mixthoroughly. Prepare a fresh solution daily.6.4 Reagents, as described in Test Method D 2194, for thestandardization of formaldhyde solution (see 6.3.1).6.4.1 Sodium Sulfi

34、te Solution, 12.5 % mass, aqueous. Dis-solve 125 g of anhydrous sodium sulfite (Na2SO3) in water anddilute to 1 L.NOTE 3Sodium sulfite gradually oxidizes to sodium sulfate on3Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For Suggestions on the

35、 testing of reagents notlisted by the American Chemical Society, see Annual Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.E2313082exposure to air and therefore shoul

36、d be kept in a tightly closed container.For best results freshly prepared reagent should be used.6.4.2 Sulfuric Acid, 0.5 mol/m3(1.0 N). Prepare and stan-dardize sulfuric acid (H2SO4) against 0.5 mol/m3(0.5 N)sodium hydroxide (NaOH) solution which has been standard-ized against potassium acid phthal

37、ate to a thymolphthalein endpoint.6.4.3 Thymolphthalein Indicator, 0.1 % mass, alcohol solu-tion. Dissolve 1.0 g of thymolphthalein in 100 mL of methanol,ethanol, or isopropanol and dilute to 1 L with additionalalcohol.6.5 Ethylene Glycol Quality Control SampleFiber gradeMEG, DEG or TEG (only requir

38、ed if maintaining a controlchart, see 10.9). Store at a temperature between 0 and 5C.Warm to ambient temperature before use.7. Sampling, Test Specimens, and Test Units7.1 Follow the relevant instructions for sampling as given inPractice E 300.8. Preparation of Apparatus8.1 SpectrophotometerCheck the

39、 performance of thespectrophotometer at regular intervals according to the guide-lines given in Practice E 275 and the manufacturers instruc-tion manual.8.2 GlasswareThoroughly clean the cells and other glass-ware using 50 % (V/V) hydrochloric acid (WarningSee6.1.3) according to the guidelines in Pr

40、actice E 275.Iftheglassware is persistently stained by iron (III) chloride, clean theaffected glassware in a concentrated hydrochloric acid bath. Donot use acetone for cleaning, since this reacts with MBTH.9. Calibration9.1 Introduce the amounts of reagents as listed in Table 1into separate 100-mL v

41、olumetric flasks (see 8.2) in the follow-ing way: First introduce the standard formaldehyde solutionand water by means of a pipette, followed by MBTH solution.9.2 Proceed as described in 10.6 through 10.8, measuringthe absorbances of the calibration solutions, including theblank solutions, against w

42、ater at 635 nm in a 10-mm cell.9.3 Correct the absorbances measured for the calibrationsolutions by subtracting the mean absorbance found for thethree blank solutions. If the mean blank absorbance exceeds itsupper control limit, the glassware must be cleaned and thecalibration repeated (see 10.9).9.

43、4 Calculate the exact amount, in g, of formaldehydepresent in each of the 7 calibration solutions, which will be inthe order of 0.0, 4.0, 8.0, 16.0, 24.0, 32.0 and 40.0 g.9.5 Construct a calibration graph by plotting the correctedabsorbances against the corresponding amount of formalde-hyde in each

44、calibration solution. Apply simple linear regres-sion to obtain the best straight line (calibration function).NOTE 4Many spectrophotometers have the ability to calculate acalibration graph automatically after measuring the calibration solutionsand subsequently to show the amount/concentration of the

45、 componentbeing measured directly on a display. In such cases, no calibration graphsneed to be constructed and the calculation can be started with 11.2. It is,however, recommended to verify the calculation procedure of the instru-ment and to establish the characteristics of the calibration graph acc

46、ordingto suitable regression analysis software.NOTE 5The entire calibration graph is based on only one startingsolution. In such a case, a weighing error, for example, could introducesignificant errors when reading concentrations in test solutions. It is,therefore, recommended to either:(i) Prepare

47、a separately weighed control solution with an accuratelyknown amount of approximately 20 g of formaldehyde and perform 9.2,measuring the absorbance of the control solution. Obtain the amount offormaldehyde of the control solution from the calibration graph/function.If this value and the calculated v

48、alue of the control solution differ by morethan 5 % of their mean, repeat the calibration.(ii) Maintain a record or control chart of the slope of the calibrationgraph. If a significant difference with earlier values is obtained, repeat thecalibration.10. Procedure10.1 Although the determination in t

49、his procedure is de-scribed such that only one test result is obtained, it is stronglyrecommended to perform a second (duplicate) determination toenable comparison of the duplicate results with the listedrepeatability value.10.2 Place a 100-mL volumetric flask onto the balance andtare or record the tare weight to the nearest 0.1 mg. Pipet 1 mLof sample into the flask, reweigh the flask and record theincrease in weight as the mass of the sample (m2).10.3 Using a pipette, add 4 mL water to the sample flask tomake a total volume of 5 mL in each flask.10.4