1、Designation: E 394 00 (Reapproved 2004)Standard 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,
2、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 covers the determination of iron in therange from 1 to 100 g.1.2 This test method is int
3、ended to be general 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 Revi
4、ew the current material safety data sheets (MSDS)for detailed information concerning toxicity, first-aid proce-dures, handling, and safety precautions.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
5、 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:D 1193 Specification for Reagent Water2E 60 Practice for Photometric and SpectrophotometricMethods for Chemical Analysis o
6、f MetalsE 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 Reagent Solutions for ChemicalAnalysisE 275 Practice for Describing and Measuring Performan
7、ceof Ultraviolet, Visible, and Near Infrared Spectrophotom-eters3. 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 dissolved in a suitable solvent and the ironis reduced to the divalent state
8、 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 suitable photometer. The absorbance of thesolution, once the color is develope
9、d, 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 the iron andsample matrix soluble in water or other suitable solvent (se
10、e10.1 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 described in Section 5.5. Interferences5.1 Fortune and Mellon3have made a co
11、mprehensive 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 ppm iron. If the maximum level of 500 ppm does notinterfere, it is very likely that the ion w
12、ill not interfere in anyquantity. 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 interferences, the original literature should beconsulted.5.2 Aldehydes, ketones, and
13、 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 direct responsibility of SubcommitteeE15.01 on General StandardsCurrent edition approve
14、d Oct. 1, 2004. Published November 2004. Originallyapproved in 1970. Last previous edition approved in 2000 as E 394 00.2For 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
15、 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. 6064.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6. A
16、pparatus6.1 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 regular intervals according to theguidelines given in Practice E 275 and the manufacturersmanual.NOTE 1If a filter photometer is used, a narrow band fil
17、ter having itsmaximum transmission at 480 to 520 nm should be used. A discussion ofphotometers and photometric practice is given in Practice E60.6.2 Absorption Cells, 5-cm or 1-cm light path.7. Reagents and Materials7.1 Purity of ReagentsUnless otherwise indicated, it isintended that all reagents sh
18、all conform to the specifications ofTABLE 1 Effect of Cations on the Determination of 2 ppm IronIon Added AsMaximum Added WithoutInterference, ppmApplicable 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
19、.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 2.09.0Cobalt 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
20、.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 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
21、 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 Determination of 2 ppm IronIon Added AsMaximum Added WithoutInterference, ppmApplicable pH RangeAcetate NaC2H3O2500 2.09.0Tetraborate Na2B4O7500 3.09.0Bromide NaBr 500 2.0
22、9.0Carbonate Na2CO3500 3.09.0Chlorate KClO3500 2.59.0Chloride NaCl 1000 2.09.0Citrate H3C6H5O7500 2.09.0Cyanide KCN 10 2.09.0Dichromate 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 2.09.0Phosph
23、ate (NH4)2HPO420 2.09.0Pyrophosphate Na4P2O750 6.09.0Silicate Na2SiO3100 2.04.5Sulfate (NH4)2SO4500 2.09.0Sulfite Na2SO3500 2.09.0Tartrate (NH4)2C4H9O6500 3.09.0Thiocyanate KCNS 500 2.09.0Thiosulfate Na2S2O3500 3.09.0E 394 00 (2004)2the Committee onAnalytical Reagents of theAmerican Chemi-cal Societ
24、y, where such specifications are available.4Othergrades 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.7.2 Purity of WaterUnless otherwise indicated, referencesto water shall be underst
25、ood to mean Type II reagent water asdefined in Specification D 1193.7.3 Hydroxylamine Hydrochloride Solution (100 g/L)Dissolve 10 g of 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
26、 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. 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 prepar
27、edby weighing exactly 0.7022 g of iron (II) ammonium sulfate hexahydrate(FeSO4(NH4)2SO46H2O, minimum purity, 99.5 %) in 500 mL of watercontaining 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)Di
28、ssolve 0.9 g of1,10-phenanthroline monohydrate in 30 mL of methanol anddilute to 300 mL with water.5,77.6 Ammonium AcetateAcetic Acid 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.
29、58. Sampling8.1 Because this is a general test method for the final stepsin determining iron, specific procedures for sample preparationare 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
30、 thestandard iron solution to each of six 100-mL, glass-stopperedgraduated cylinders. These cylinders contain 0, 20, 40, 60, 80,and 100 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 descri
31、bed in10.3 and 10.4.9.2 Plot, on linear graph paper, the micrograms of iron as afunction of absorbance.NOTE 3If the photometer readings 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 transmitt
32、ance.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, 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 t
33、hree significant figures a sample (pH lessthan 2) containing 1 to 100 g of iron into a 100-mL,glass-stoppered graduated cylinder (Note 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
34、 used (Note 6).NOTE 5The sample size should not exceed 80 mL. When using largesamples, the miscibility of the samples and the reagents 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
35、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 suitable for use withoutrecalibration include water, methanol, acetic acid, acetonitrile, and di- andtriethylene glycol. Acetone is not suitable. No solvents other than
36、thoselisted have been tested.10.2 To prepare a reagent blank, add a quantity of water,approximately equal to the sample size in volume, 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 blanki
37、s needed. The reagent blank should have the same composition afterdilution as the sample. For example, if 10 mL of methanol is taken 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 i
38、ncluded in the reagent blank.10.3 Add to each cylinder 2 mL of the hydroxylaminehydrochloride solution. Stopper and mix well by inverting 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 ad
39、dition of theammonium acetate-acetic acid solution (see Note 8). It may benecessary to adjust the pH of the blank by the addition of 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 severa
40、l times.Allow thesample solution and reagent blank to sit at room temperaturefor a minimum of 15 min.NOTE 8It is permissible to prepare 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
41、 flask or4Reagent 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 States P
42、harmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.5This solution is also described in Practice E 200.6This solution is used for calibration only.7Frederick, G., and Richter, F. P., Phenanthrolines and Substituted Phenanthro-line Indicators, GFS Publication N
43、o. 205, 1944 (no charge).E 394 00 (2004)3graduated cylinder for final dilution.10.4 Measure the absorbance of each sample solution atapproximately 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 a
44、t zero absorbanceor 100 % transmittance.NOTE 9If a filter photometer is used, the same filter should be usedfor the calibration and sample determinations. When using a spectropho-tometer, the wavelength of maximum absorption in the vicinity of 510 nmshould be used. This may be determined by scanning
45、 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 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 t
46、he iron content of the sample as follows(Note 11):Iron, ppm 5BW(3)where:B = micrograms of iron found, andW = grams of sample.NOTE 11If the 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 = mi
47、crograms of iron,S = slope of the calibration line, andL = cell path length, cm.12. Report12.1 Report the iron content to the nearest 0.01 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)T
48、he coefficient ofvariation for a single determination has been estimated to bethe amount shown in Table 3 at the indicated degrees 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 coeffic
49、ient 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 (Multilaboratory)The coefficientof variation of results (each the average of duplicates), ob-tained by analysts on different laboratories, has been estimatedto be the amount shown in Table 3
