1、Designation: E1615 08E1615 16Standard Test Method forIron in Trace Quantities Using the FerroZine Method1This standard is issued under the fixed designation E1615; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last re
2、vision. 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 the range from 0.01 to 0.2 g/g using FerroZine2 reagent solution. Thera
3、nge may be extended through the use of a 5- or 10-cm cell or by suitable dilution of the sample solution.1.2 This test method is intended to be general for the final steps in the determination of iron and does not include proceduresfor sample preparation.1.3 The values stated in SI units are to be r
4、egarded as standard. No other units of measurement are included in this standard.1.4 Review the current material safety data sheets (MSDS) Safety Data Sheets (SDS) for detailed information concerningtoxicity, first-aid procedures, and safety precautions.1.5 This standard does not purport to address
5、all of the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use. For specific warning statements, see 7.4.2. Referenced Documen
6、ts2.1 ASTM Standards:3D1193 Specification for Reagent WaterE60 Practice for Analysis of Metals, Ores, and Related Materials by SpectrophotometryE180 Practice for Determining the Precision of ASTM Methods for Analysis and Testing of Industrial and Specialty Chemicals(Withdrawn 2009)4E200 Practice for
7、 Preparation, Standardization, and Storage of Standard and Reagent Solutions for Chemical AnalysisE275 Practice for Describing and Measuring Performance of Ultraviolet and Visible Spectrophotometers3. Summary of Test Method3.1 This test method is based upon a photometric determination of the FerroZi
8、ne2 complex with the iron (II) ion.5,6 The sampleis dissolved in a suitable solvent and the iron is reacted with FerroZine reagent solution which will convert the dissolved ironcompounds to form a magenta color iron (II) complex. The iron content of the sample solution is determined by measurement o
9、fthe magenta color at 560 nm using a suitable photometer.4. Significance and Use4.1 This test method is suitable for determining trace concentrations of iron in a wide variety of products, provided thatappropriate sample preparation has rendered the iron and sample matrix soluble in water or other s
10、uitable solvent. Each samplematrix must be investigated for suitability using this test method.4.2 This test method assumes that the amount of color developed is proportional to the amount of iron in the test solution. Thecalibration curve is linear over the specified range.1 This test method is und
11、er the jurisdiction of ASTM Committee E15 on Industrial and Specialty Chemicalsand is the direct responsibility of Subcommittee E15.01 onGeneral Standards.Current edition approved April 1, 2008April 1, 2016. Published May 2008May 2016. Originally approved in 1994. Last previous edition approved in 2
12、0052008 asE161505.08. DOI: 10.1520/E1615-08.10.1520/E1615-16.2 FerroZine is a trademark of Hach Chemical Company.3 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the
13、standards Document Summary page on the ASTM website.4 The last approved version of this historical standard is referenced on www.astm.org.5 Stookey, L. L., “FerroZineA New Spectrophotometric Reagent for Iron,” Analytical Chemistry, Vol 42, No. 7, June 1970, pp. 779 781.6 Gibbs, C. R., “Characterizat
14、ion and Application of FerroZine Iron Reagent as a Ferrous Iron Indicator,” Analytical Chemistry , Vol 48, No. 8, July 1976, pp. 11971201.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous ve
15、rsion. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.*A Summary of Changes se
16、ction appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15. Interferences5.1 Any ion that absorbs light at 560 nm will interfere with the determination. Anionic interferences include oxalate inconcentra
17、tions over 500 g/g, cyanide, and nitrate.55.2 Of copper, cobalt, calcium, magnesium, lead, silver, molybdenum, aluminum, nickel, zinc, arsenic, manganese, hexavalentchromium, trivalent chromium, divalent cobalt and monovalent copper are the only metals other than iron that form colored specieswith F
18、erroZine under test conditions. At least 1000 mg/L of the alkali metals and the alkaline earths had no effect on thedetermination. Many heavy metals will react with FerroZine in competition with iron, but with the excess reagent used in the testthere is no effect on the results.55.3 The pH range of
19、the final solution should be from 4 to 9 to give the best test results.5,65.4 All glassware used in this test method must be iron-free and scrupulously clean by precleaning with dilute hydrochloric acidand FerroZine reagent solution followed by a water rinse.6. Apparatus6.1 Photometer, capable of me
20、asuring light absorption at 560 nm and holding a 5-cm or 10-cm cell. Check the performance ofthe photometer at regular intervals according to the guidelines given in Practice E275 and the manufacturers manual.6.2 Absorption Cells, 5-cm or 10-cm light path.NOTE 1A discussion of photometers and photom
21、etric practice is given in Practice E60.7. Reagents7.1 Unless otherwise indicated, it is intended that all reagents shall conform to the specifications of the Committee onAnalyticalReagents of the American Chemical Society, where such specifications are available.7 Other grades may be used, provided
22、 it isfirst ascertained that the reagent is of sufficiently high purity to permit its use without lessening the accuracy of the determination.7.2 Purity of WaterUnless otherwise indicated, references to water shall be understood to mean Type II or Type III reagentwater conforming to Specification D1
23、193.7.3 Iron, Standard Solution, 1 mL = 1 g Fe (see Note 2Notes 2 and 3 and Note 3)Dissolve 0.1000 g of iron wire in 10 mLof hydrochloric acid (HCl, 1 + 1) and 1 mL of saturated bromine water (400 mL water + 20 mL bromine). Boil until the excessbromine is removed. Add 200 mL of HCl, cool, and dilute
24、 to 1 L 1 L in a volumetric flask. Dilute 10 mL of this solution to 1 L.NOTE 2The preparation of this reagent is also described in Practice E200.NOTE 3As an alternative, the standard iron solution may be prepared by diluting 1.00 mL of commercially available iron standard stock solution(1000 mg iron
25、/L) to 1 L with water.7.4 FerroZine Reagent SolutionContains FerroZine color reagent 3-(2-pyridyl)-5,6-bis(4-phenylsulfonic acid)-1,2,4-triazine,monosodium salt, monohydrate, buffer, and a reducing agent. (WarningThis solution contains thiols as reducing agents. Wearbutyl rubber or neoprene gloves w
26、hen handling the solution and avoid inhalation of the vapors.Warning)This solution containsthiols as reducing agents. Wear butyl rubber or neoprene gloves when handling the solution and avoid inhalation of the vapors.)7.4.1 Alternatively, the individual solutions can be prepared as described below.5
27、7.4.1.1 Reducing AgentHydroxylamine hydrochloride, 10 percent by weight solution in hydrochloric acid: Dissolve 10 g ofreagent grade hydroxylamine hydrochloride (NH2OH.HCL) in 30 g of deionized water in a plastic bottle; add 50 mL of reagentgrade concentrated hydrochloric acid and mix well. Prepare
28、this solution fresh daily.7.4.1.2 Color ReagentFerroZine, 0.514 weight percent solution: Dissolve 0.514 g of FerroZine reagent in 100 g of deionizedwater in a plastic bottle, and mix well. Discard the reagent after seven days.7.4.1.3 Buffer Reagent-pH 10.0 BufferDissolve 200 g of reagent grade ammon
29、ium acetate in a minimum of deionized water,add 175 mLof concentrated ammonium hydroxide and dilute to 500 mLin a volumetric flask. Mix well. Check the pH of the bufferto verify that it is pH 10 6 0.5. If it is not in the required pH range, remake the buffer. Store the buffer in a plastic bottle. Di
30、scardafter four weeks.8. Sampling8.1 Because this is a general test method for the final steps in determining iron, specific procedures for sample preparation arenot included (see 4.1 and 4.2).9. Calibration9.1 FerroZine Reagent Solution Method (7.4):7 Reagent Chemicals, American Chemical Society Sp
31、ecifications, , American Chemical Society, Washington, DC. For suggestions on the testing of reagents not listed bythe American Chemical Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and NationalFormulary, U.S. Pharmacopeial
32、 Convention, Inc. (USPC),(USP), Rockville, MD.E1615 1629.1.1 By means of suitable pipets or a buret, transfer 0 (reagent blank), 0.5, 1.0, 2.0, 4.0, 6.0, 8.0, and 10.0 mL, respectively,of the standard iron solution and approximately 20 mL of water to each of eightsix clean, dry, 50-mL, glass-stopper
33、ed volumetricflasks. These flasks represent 0, 0.5, 1.0, 2.0, 4.0, 6.0, 8.0, and 10.0 g of iron. Add 2.0 mL of FerroZine reagent solution to eachflask, dilute the contents of each flask to volume with water, stopper, and mix well by inverting the flasks several times. Let thesolutions stand for a mi
34、nimum of 5 min but not more than 10 min to develop the magenta color. Measure the absorbance of eachcalibration standard in accordance with 10.3.9.2 Individual Solution Method (7.4.1):9.2.1 By means of suitable pipets or a buret, transfer 0 (reagent blank), 1.0, 2.0, 4.0, 6.0, 8.0, 10.0 and 20.010.0
35、 mL, respectively,of the standard iron solution and approximately 40 mL of water to each of eightsix clean, dry, 100-mL, glass-stoppered volumetricflasks. These flasks represent 0, 1.0, 2.0, 4.0, 6.0, 8.0, 10.0 and 20.010.0 g of iron.Add the individual reagents (reducing reagent,color reagent and bu
36、ffer reagent) as described in 10.2 and 10.3 to each flask, dilute the contents of each flask to volume with water,stopper, and mix well by inverting the flasks several times. Let the solutions stand for a minimum of 5 min but not more than 20min to develop the magenta color. Measure the absorbance o
37、f each calibration standard in accordance with 10.3.9.3 Plot, on linear graph paper, the Construct a calibration graph by plotting the absorbances against the correspondingmicrograms of iron as a function of absorbance.present in the calibration solutions, including the blank. Obtain the best straig
38、htline through the points (calibration function) by applying simple linear regression. Determine the slope (S) of the linear calibrationfunction.NOTE 4If the photometer readings are percent transmittance, they may be plotted on semilog paper or converted to absorbance as follows:A 5log100/T! (1)wher
39、e:A = absorbance, andT = transmittance, %.9.3.1 Evaluate and verify the obtained calibration graph and function by checking for a random scatter of the y-residuals aroundan average of zero, and by preparing and analyzing a control solution.NOTE 4Many spectrophotometers have the ability to calculate
40、a calibration graph automatically after measuring the calibration solutions andsubsequently to show the concentration of the component being measured directly on a display. In such cases no manual calibration graphs need to beconstructed. It is, however, recommended to verify the calculation procedu
41、re of the instrument and to establish the characteristics of the calibration graphaccording to suitable regression analysis software.NOTE 5As the calibration function has been derived from a single prepared calibration standard, verify the accuracy of the calibration function bypreparing and analyzi
42、ng a control solution containing an accurately known amount of approximately 5 g of iron. If reasonably possible this controlsolution should be completely independent, that is, prepared by a different operator, different batches of chemicals etc. The difference between the knownvalue and the measure
43、d value should be within the confidence limits for the control solution, as derived from the confidence limits of intercept and slopeof the calibration function.NOTE 5If desired, the slope of the calibration line may be calculated as follows:S 5L 3W (2)where:S = slope of calibration line, g Fecm/abs
44、orbance unit,L = cell path length, cm, andW = iron, g, corresponding to an absorbance of 1.000 on the calibration line.NOTE 6Many spectrophotometers have the ability to calculate a calibration graph automatically after measuring the calibration solutions andsubsequently to show the concentration of
45、the component being measured directly on a display. In such cases no manual calibration graphs need to beconstructed. It is, however, recommended to verify the calculation procedure of the instrument and to establish the characteristics of the calibration graphaccording to suitable regression analys
46、is software.NOTE 7The entire calibration graph is based on only one starting solution (standard iron solution). In such a case a weighing error, for example, couldintroduce significant errors when reading concentrations of test solutions. It is, therefore, recommended to prepare a separately weighed
47、 control solutioncontaining an accurately known amount of approximately 5 g of iron. Measure the absorbance of this solution according to 10.3. Obtain the ironconcentration of the control solution from the calibration graph/function. If this value and the calculated value of the control solution dif
48、fer by more than5 % of their mean, repeat the calibration.10. Procedure10.1 FerroZine Reagent Solution Method (7.4):10.1.1 Weigh to three significant figures a sample containing 0.5 to 10 g of iron into a clean, dry 50-mL, glass-stoppered,volumetric flask (see Note 86). Add sufficient water to disso
49、lve the sample but do not exceed 40 mL total volume.NOTE 6Preliminary tests must be made to determine if the sample or any impurities in the sample interfere in any way with the analysis.10.1.2 To prepare a reagent blank, add about 20 mL of water to a second clean, dry, 50-mL, glass-stoppered, volumetric flask.NOTE 7When running a number of samples, only one reagent blank is needed.E1615 16310.1.3 Add 2.0 mLof the FerroZine reagent solution to each volumetric flask, stopper, and swirl to mix the contents. Dilute eachvolumetric flask to volum
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