1、Designation: E 394 09Standard Test Method forIron in Trace Quantities Using the 1,10-PhenanthrolineMethod1This standard is issued under the fixed designation E 394; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last r
2、evision. A number in parentheses 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 iron in therange from 1 to 100 g.1.2 This test method is intended to be genera
3、l for the finalsteps in the determination of iron and does not includeprocedures for sample preparation.1.3 This test method is applicable to samples whose solu-tions have a pH less than 2. It is assumed that the pH isadjusted to within this range in the sample preparation.1.4 Review the current mat
4、erial safety data sheets (MSDS)for detailed information concerning toxicity, first-aid proce-dures, handling, and safety precautions.1.5 The values given in SI units are the standard. Values inparentheses are for information only.1.6 This standard does not purport to address all of thesafety concern
5、s, 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 Standards:2D 1193 Specification for Reagent WaterE60
6、Practice for Analysis of Metals, Ores, and RelatedMaterials by Molecular Absorption SpectrometryE 180 Practice for Determining the Precision of ASTMMethods for Analysis and Testing of Industrial and Spe-cialty ChemicalsE 200 Practice for Preparation, Standardization, and Stor-age of Standard and Rea
7、gent Solutions for ChemicalAnalysisE 275 Practice for Describing and Measuring Performanceof Ultraviolet and Visible Spectrophotometers3. Summary of Test Method3.1 This test method is based upon a photometric determi-nation of the 1,10-phenanthroline complex with the iron(II)ion. The sample is disso
8、lved in a suitable solvent and the ironis reduced to the divalent state by the addition of hydroxy-lamine hydrochloride. The color is then developed, by theaddition of 1,10-phenanthroline. After a short reaction period,the absorbance of the solution is measured at approximately510 nm using a suitabl
9、e photometer. The absorbance of thesolution, once the color is developed, is stable for at leastseveral months.4. Significance and Use4.1 This test method is suitable for determining traceconcentrations of iron in a wide variety of products, providedthat appropriate sample preparation has rendered t
10、he iron andsample matrix soluble in water or other suitable solvent (see10.1 and Note 6).4.2 This test method assumes that the amount of colordeveloped is proportional to the amount of iron in the testsolution. The calibration curve is linear over the specifiedrange. Possible interferences are descr
11、ibed in Section 5.5. Interferences5.1 Fortune and Mellon3have made a comprehensive studyof the interferences of various inorganic ions in this determi-nation. Table 1 and Table 2, taken from their report, show theeffects of various cations and anions on the determination of2.0 g/g (ppm) iron. If the
12、 maximum level of 500 g/g (ppm)does not interfere, it is very likely that the ion will not interferein any quantity. The data were obtained under slightly differentconditions than those specified in the present test method, butthe interferences should be similar. For a more detaileddescription of in
13、terferences, the original literature should beconsulted.5.2 Aldehydes, ketones, and oxidizing agents interfere byconsuming the hydroxylamine hydrochloride added as a reduc-ing agent.1This test method is under the jurisdiction of ASTM Committee E15 onIndustrial and Specialty Chemicals and is the dire
14、ct responsibility of SubcommitteeE15.01 on General Standards.Current edition approved April 1, 2009. Published May 2009. Originallyapproved in 1970. Last previous edition approved in 2004 as E 394 00(2004).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer
15、Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Fortune, W. B., and Mellon, M. G., Industrial and Engineering Chemistry,Analytical Edition, IENAA Vol 10, 1938, pp. 6064.1*A Summary of Changes section ap
16、pears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6. Apparatus6.1 Photometer, capable of measuring light absorption at510 nm and holding a 5-cm or 1-cm cell. Check the perfor-mance of the photometer at
17、regular intervals according to theguidelines given in Practice E 275 and the manufacturersmanual.NOTE 1If a filter photometer is used, a narrow band filter having itsmaximum transmission at 480 to 520 nm should be used. A discussion ofphotometers and photometric practice is given in Practice E60.6.2
18、 Absorption Cells, 5-cm or 1-cm light path.7. Reagents and Materials7.1 Purity of ReagentsUnless otherwise indicated, it isintended that all reagents shall conform to the specifications ofTABLE 1 Effect of Cations on the Determination of 2 g/g (ppm) IronIon Added AsMaximum Added WithoutInterference,
19、 g/g (ppm)Applicable pH RangeAluminum AlCl3500 2.03.0Ammonium NH4Cl 500 2.09.0Antimony SbCl330 3.09.0Arsenic As2O5500 3.09.0Arsenic As2O3500 3.09.0Barium BaCl2500 3.09.0Beryllium Be(NO3)2500 3.05.5Bismuth Bi(NO3)3.A.ACadmium Cd(NO3)250 3.09.0Calcium Ca(NO3)2500 2.09.0Chromium Cr2(SO4)320 2.09.0Cobal
20、t Co(NO3)210 3.05.0Copper Cu(NO3)210 2.54.0Lead Pb(C2H3O2)2500 2.09.0Lithium LiCl 500 2.09.0Magnesium Mg(NO3)2500 2.09.0Manganese MnSO4500 2.09.0Mercury HgCl21 2.09.0Mercury Hg2(NO3)210 3.29.0Molybdenum (NH4)6Mo7O24100 5.59.0Nickel Ni(NO3)22 2.59.0Potassium KCl 1000 2.09.0Silver AgNO3.A.ASodium NaCl
21、 1000 2.09.0Strontium Sr(NO3)2500 2.09.0Thorium Th(NO3)4250 2.09.0Tin H2SnCl620 3.06.0Tin H2SnCl410 2.06.0Tungsten Na2WO410 2.59.0Uranium UO2(C2H3O2)2100 2.06.0Zinc Zn(NO3)210 2.09.0Zirconium Zr(NO3)450 2.09.0AMust be completely absent because of precipitation.TABLE 2 Effect of Anions on the Determi
22、nation of 2 g/g (ppm) IronIon Added AsMaximum Added WithoutInterference, g/g (ppm)Applicable pH RangeAcetate NaC2H3O2500 2.09.0Tetraborate Na2B4O7500 3.09.0Bromide NaBr 500 2.09.0Carbonate Na2CO3500 3.09.0Chlorate KClO3500 2.59.0Chloride NaCl 1000 2.09.0Citrate H3C6H5O7500 2.09.0Cyanide KCN 10 2.09.
23、0Dichromate K2Cr2O720 2.59.0Fluoride NaF 500 4.09.0Iodide KI 500 2.09.0Nitrate KNO3500 2.09.0Nitrite KNO2500 2.59.0Oxalate (NH4)2C2O4500 6.09.0Perchlorate KClO4100 2.09.0Phosphate (NH4)2HPO420 2.09.0Pyrophosphate Na4P2O750 6.09.0Silicate Na2SiO3100 2.04.5Sulfate (NH4)2SO4500 2.09.0Sulfite Na2SO3500
24、2.09.0Tartrate (NH4)2C4H9O6500 3.09.0Thiocyanate KCNS 500 2.09.0Thiosulfate Na2S2O3500 3.09.0E394092the Committee onAnalytical Reagents of theAmerican Chemi-cal Society, where such specifications are available.4Othergrades may be used, provided it is first ascertained that thereagent is of sufficien
25、tly high purity to permit its use withoutlessening the accuracy of the determination.7.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean Type II reagent water asdefined in Specification D 1193.7.3 Hydroxylamine Hydrochloride Solution (100 g/L)Dissolve 10 g o
26、f hydroxylamine hydrochloride (HONH2 HCl)in approximately 60 mL of water, filter, and dilute to 100 mL.57.4 Iron, Standard Solution (1 mL = 0.01 mg Fe)6(Note2)Dissolve 0.1000 g of iron wire in 10 mL of hydrochloricacid (HCl, 1 + 1) and 1 mL of bromine water. Boil until theexcess bromine is removed.
27、Add 200 mL of HCl, cool, anddilute to 1 L in a volumetric flask. Dilute 100 mL of thissolution to 1 L.NOTE 2As an alternative, the standard iron solution may be preparedby weighing exactly 0.7022 g of iron (II) ammonium sulfate hexahydrate(FeSO4(NH4)2SO46H2O, minimum purity, 99.5 %) in 500 mL of wat
28、ercontaining 20 mL of sulfuric acid (H2So4, sp gr 1.84) and diluting to 1 Lwith water. Dilute 100 mL of this solution to 1 L.7.5 1,10-Phenanthroline Solution (3 g/L)Dissolve 0.9 g of1,10-phenanthroline monohydrate in 30 mL of methanol anddilute to 300 mL with water.5,77.6 Ammonium AcetateAcetic Acid
29、 SolutionDissolve100 g of ammonium acetate (CH3COONH4) in about 600 mLof water, filter, add 200 mL of glacial acetic acid to the filtrate,and dilute to 1 L with water.58. Sampling8.1 Because this is a general test method for the final stepsin determining iron, specific procedures for sample preparat
30、ionare not included (see 1.3, 4.1 and 4.2).9. Calibration9.1 By means of suitable pipets or a buret, transfer 0(reagent blank), 2, 4, 6, 8, and 10 mL, respectively, of thestandard iron solution to each of six 100-mL, glass-stopperedgraduated cylinders. These cylinders contain 0, 20, 40, 60, 80,and 1
31、00 g of iron, respectively. Dilute the contents of eachcylinder to 80 mL with water. Develop the color and measurethe absorbance of each calibration standard as described in10.3 and 10.4.9.2 Plot, on linear graph paper, the micrograms of iron as afunction of absorbance.NOTE 3If the photometer readin
32、gs are percent transmittance, theymay be plotted on semi-log paper or converted to absorbance as follows:A 5 logS100TD(1)where:A = absorbance, andT = percent transmittance.NOTE 4If desired, the slope of the calibration line may be calculatedas follows:S 5 L 3 W (2)where:S = slope of calibration line
33、, gFecm/absorbance unit,L = cell path length, cm, andW = micrograms of iron corresponding to an absorbanceof 1.000 on the calibration line.10. Procedure10.1 Weigh to three significant figures a sample (pH lessthan 2) containing 1 to 100 g of iron into a 100-mL,glass-stoppered graduated cylinder (Not
34、e 5). If the sample iswater soluble, dissolve it in water and dilute to 80 mL withwater. If the sample is not water soluble, methanol or anothersuitable solvent may be used (Note 6).NOTE 5The sample size should not exceed 80 mL. When using largesamples, the miscibility of the samples and the reagent
35、s should be checkedbefore the determination is made. In any case, preliminary tests must bemade to determine if the sample or any impurities in the sample interferein any way with the analysis. If a 1-cm cell is used, the sample mustcontain at least 5 g of iron.NOTE 6Solvents that have been found su
36、itable for use withoutrecalibration include water, methanol, acetic acid, acetonitrile, and di- andtriethylene glycol. Acetone is not suitable. No solvents other than thoselisted have been tested.10.2 To prepare a reagent blank, add a quantity of water,approximately equal to the sample size in volum
37、e, to a secondgraduated cylinder. Dilute this to 80 mL with the same solventused to dissolve the sample.NOTE 7When running a number of samples, only one reagent blankis needed. The reagent blank should have the same composition afterdilution as the sample. For example, if 10 mL of methanol is taken
38、as asample, 10 mL of spectro pure methanol should be included in the reagentblank. If 25 mL of methanol is taken as a sample, 25 mL of spectro puremethanol should be included in the reagent blank.10.3 Add to each cylinder 2 mL of the hydroxylaminehydrochloride solution. Stopper and mix well by inver
39、ting thecylinder several times. Add to each cylinder 5 mL of the1,10-phenanthroline solution and adjust the pH of the solutionto between 3.0 and 4.0 by the dropwise addition of theammonium acetate-acetic acid solution (see Note 8). It may benecessary to adjust the pH of the blank by the addition of
40、diluteHCl. Add to each cylinder 5 mL of the ammonium acetate-acetic acid solution and dilute to 100 mL with water. Stopperand mix well by inverting the cylinder several times.Allow thesample solution and reagent blank to sit at room temperaturefor a minimum of 15 min.NOTE 8It is permissible to prepa
41、re the solutions in 150-mL beakers tofacilitate the adjustment of the pH using a pH meter. After adjustment,quantitatively transfer the solution to a 100-mL volumetric flask or4Reagent Chemicals, American Chemical Society Specifications , AmericanChemical Society, Washington, DC. For suggestions on
42、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. (USPC), Rockville,MD.5This solution is also described in Prac
43、tice E 200.6This solution is used for calibration only.7Frederick, G., and Richter, F. P., Phenanthrolines and Substituted Phenanthro-line Indicators, GFS Publication No. 205, 1944 (no charge).E394093graduated cylinder for final dilution.10.4 Measure the absorbance of each sample solution atapproxim
44、ately 510 nm (see Note 9) in a 5-cm cell (see Note 10)using a suitable photometer. Use a matched 5-cm cell filledwith the reagent blank to set the instrument at zero absorbanceor 100 % transmittance.NOTE 9If a filter photometer is used, the same filter should be usedfor the calibration and sample de
45、terminations. When using a spectropho-tometer, the wavelength of maximum absorption in the vicinity of 510 nmshould be used. This may be determined by scanning the absorption bandaround 510 nm.NOTE 10It is permissible to use matched 1-cm cells for the photom-eter readings as long as a minimum of 5 g
46、 of iron is present in the samplesolution.10.5 Refer to a previously prepared calibration curve todetermine the g of iron found.11. Calculation11.1 Calculate the iron content of the sample as follows(Note 11):Iron, g/g ppm!5BW(3)where:B = micrograms of iron found, andW = grams of sample.NOTE 11If th
47、e slope of the calibration line has been calculated, themicrograms of iron, B, may be calculated as follows:B 5 A 3SSLD(4)where:A = absorbance of the sample,B = micrograms of iron,S = slope of the calibration line, andL = cell path length, cm.12. Report12.1 Report the iron content to the nearest 0.0
48、1 g/g (ppm).13. Precision and Bias13.1 The following criteria should be used for judging theacceptability of results (see Note 12):13.1.1 Repeatability (Single Analyst)The coefficient ofvariation for a single determination has been estimated to bethe amount shown in Table 3 at the indicated degrees
49、offreedom. The 95 % limit for the difference between two suchruns is the amount shown in Table 3.13.1.2 Laboratory Precision (Within-Laboratory, Between-Days)The coefficient of variation of results (each the averageof duplicates), obtained by the same analyst on different days,has been estimated to be the amount shown in Table 3 at theindicated degrees of freedom. The 95 % limit for the differencebetween two such averages is the amount shown in Table 3.13.1.3 Reproducibility (Multilaborato
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