1、Designation: D 1068 05e1An American National StandardStandard Test Methods forIron in Water1This standard is issued under the fixed designation D 1068; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A nu
2、mber in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.e1NOTEWarning notes were moved into the text editorially in July 20
3、05.1. Scope1.1 These test methods cover the determination of iron inwater. Procedures are given for determining total iron, dis-solved iron, and ferrous iron. Undissolved iron may becalculated from the total iron and dissolved iron determina-tions. The test methods are given as follows:Range Section
4、sTest Method AAtomic Absorption,Direct0.1 to 5.0 mg/L 7 to 15Test Method CAtomic Absorption,Graphite Furnace5to100g/L 16to24Test Method DPhotometricBathophenanthroline g/L40 to 1000 g/L 25 to 361.2 It is the users responsibility to ensure the validity ofthese test methods to waters of untested matri
5、ces.1.3 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 prior to use. Specific h
6、azardsstatements are given in Note 3, section 11.7.1, and sectionX1.1.2.1.4 Two former photometric test methods were discontin-ued. See Appendix X2 for historical information.2. Referenced Documents2.1 ASTM Standards:2D 858 Test Methods for Manganese in WaterD 1066 Practice for Sampling SteamD 1129
7、Terminology Relating to WaterD 1192 Specification for Equipment for Sampling Waterand Steam in Closed Conduits3D 1193 Specification for Reagent WaterD 1687 Test Methods for Chromium in WaterD 1688 Test Methods for Copper in WaterD 1691 Test Methods for Zinc in WaterD 1886 Test Methods for Nickel in
8、WaterD 2777 Practice for Determination of Precision and Bias ofApplicable Methods of Committee D-19 on WaterD 3370 Practices for Sampling Water from Closed ConduitsD 3558 Test Methods for Cobalt in WaterD 3559 Test Methods for Lead in WaterD 3919 Practice for Measuring Trace Elements in Water byGrap
9、hite Furnace Atomic Absorption SpectrophotometryD 4841 Practice for Estimation of Holding Time for WaterSamples Containing Organic and Inorganic ConstituentsD 5810 Guide for Spiking into Aqueous SamplesD 5847 Practice for the Writing Quality Control Specifica-tions for Standard Test Methods for Wate
10、r AnalysisE60 Practice for Analysis of Metals, Ores, and RelatedMaterials by Molecular Absorption SpectrometryE 275 Practice for Describing and Measuring Performanceof Ultraviolet, Visible, and Near Infrared Spectrophotom-eters3. Terminology3.1 Definitions: For definitions of terms used in these tes
11、tmethods, refer to Terminology D 1129.3.2 Definitions of Terms Specific to This Standard:3.2.1 total recoverable ironan arbitrary analytical termrelating to the recoverable forms of iron that are determinableby the digestion method which is included in these testmethods.4. Significance and Use4.1 Ir
12、on is the second most abundant metallic element in theearths crust and is essential in the metabolism of plants andanimals. If presented in excessive amounts, however, it forms1These test methods are under the jurisdiction of ASTM Committee D19 onWater and are the direct responsibility of Subcommitt
13、ee D19.05 on InorganicConstituents in Water.Current edition approved June 1, 2005. Published July 2005. Originally approvedin 1949. Last previous edition approved in 2003 as D 1068 03.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm
14、.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Withdrawn.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.oxyhydroxide precipitates that stain laundry and po
15、rcelain. Asa result, the recommended limit for iron in domestic watersupplies is 0.3 mg/L. These test methods are useful fordetermining iron in many natural waters.5. Purity of Reagents5.1 Reagent grade chemicals shall be used in all tests.Unless otherwise indicated, it is intended that all reagents
16、 shallconform to the specifications of the Committee on AnalyticalReagents of the American Chemical Society, where suchspecifications are available.4Other grades may be used,provided it is first ascertained that the reagent is of sufficientlyhigh purity to permit its use without lessening the accura
17、cy ofthe determination.5.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean reagent water conformingto Specification D 1193, Type I. Other reagent water types maybe used, provided it is first ascertained that the water is ofsufficiently high purity to permit
18、its use without adverselyaffecting the bias and precision of the test method. Type IIwater was specified at the time of round-robin testing of thesetest methods. In addition, water used in preparing solutions forthe determination of ferrous iron shall be freshly boiled andessentially oxygen free.6.
19、Sampling6.1 Collect the sample in accordance with Practice D 1066,Specification D 1192, or Practices D 3370, as applicable.6.2 Samples should be preserved with HNO3or HCl (sp gr1.42) to a pH of 2 or less immediately at the time of collection.If only dissolved iron is to be determined, the sample sha
20、ll befiltered through a 0.45-m membrane filter before acidification.The holding time for samples can be calculated in accordancewith Practice D 4841.6.3 If ferrous iron is to be determined, the sample should beanalyzed as soon as possible after collection and contact withatmospheric oxygen should be
21、 minimized.6.4 Additional information on sampling requirements forTest Method D is provided in 34.1.TEST METHOD AATOMIC ABSORPTION, DIRECT7. Scope7.1 This test method covers the determination of dissolvedand total recoverable iron in most waters and wastewaters.7.2 This test method is applicable in
22、the range from 0.1 to5.0 mg/L of iron. The range may be extended to concentrationsgreater than 5.0 mg/L by dilution of the sample.7.3 This test method has been used successfully withreagent water; tap, ground, and surface waters; unspecifiedwastewaters; and a refinery primary treatment water. It is
23、theusers responsibility to ensure the validity of this test methodfor waters of untested matrices.8. Summary of Test Method8.1 Iron is determined by atomic absorption spectrophotom-etry. Dissolved iron is determined by atomizing the filteredsample directly with no pretreatment. Total recoverable iro
24、n isdetermined by atomizing the sample following hydrochloric-nitric acid digestion and filtration. The same digestion proce-dure may be used to determine total recoverable nickel (TestMethods D 1886), chromium (Test Methods D 1687), cobalt(Test Methods D 3558), copper (Test Methods D 1688), lead(Te
25、st Methods D 3559), manganese (Test Methods D 858), andzinc (Test Methods D 1691).9. Interferences9.1 Sodium, potassium, barium, chloride and sulfate (5000mg/L each), calcium, magnesium, chromium, manganese,cobalt, nickel, copper, zinc, palladium, silver, cadmium, tin,lead, lithium, mercury, seleniu
26、m, aluminum, antimony, arsenic,vanadium, boron, and molybdenum (100 mg/L) do not inter-fere.9.2 Background correction (or chelation-extraction) may benecessary to determine low levels of iron in some waters.NOTE 1Instrument manufacturers instructions for use of the specificcorrection technique shoul
27、d be followed.10. Apparatus10.1 Atomic Absorption Spectrophotometer, for use at 248.3nm.NOTE 2The manufacturers instructions should be followed for allinstrumental parameters. A wavelength other than 248.3 nm may be usedif it has been determined to be equally suitable.10.1.1 Iron Hollow-Cathode Lamp
28、Multielement hollow-cathode lamps are available and have also been found satis-factory.10.2 Pressure-Reducing ValvesThe supplies of fuel andoxidant shall be maintained at pressures somewhat higher thanthe controlled operating pressure of the instrument by suitablevalves.11. Reagents and Materials11.
29、1 Hydrochloric Acid (sp gr 1.19)Concentrated hydro-chloric acid (HCl).NOTE 3If the reagent blank concentration is greater than the methoddetection limit, distill the HCl or use a spectrograde acid. PrecautionWhen HCl is distilled an azeotropic mixture is obtained (approximately 6N HCl). Therefore, w
30、hen concentrated HCl is specified for the preparationof reagents or in the procedure, use double the volume specified if distilledacid is used.11.2 Nitric Acid (sp gr 1.42)Concentrated nitric acid(HNO3).NOTE 4If the reagent blank concentration is greater than the methoddetection limit, distill the H
31、NO3or use a spectrograde acid.11.3 Nitric Acid (1 + 499)Add 1 volume of HNO3(sp gr1.42) to 499 volumes of water.4Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Societ
32、y, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmaceutical Convention, Inc. (USPC), Rockville,MD.D106805e1211.4 Iron Solution, Stock (1 mL = 1.0 mg Iron)Dissolve1.000 g of pure iron in 100 mL of HCL (1
33、 + 1) with the aid ofheat. Cool and dilute to 1 L with water.11.5 Iron Solution, Standard (1 mL = 0.1 mg Iron)Dilute100.0 mL of the iron stock solution to 1 L with water.11.6 Oxidant:11.6.1 Air, which has been passed through a suitable filter toremove oil, water, and other foreign substances is the
34、usualoxidant.11.7 Fuel:11.7.1 AcetyleneStandard, commercially available acety-lene is the usual fuel. Acetone, always present in acetylenecylinders can affect analytical results. The cylinder should bereplaced at 50 psig (345 kPa). (Warning“Purified” gradeacetylene containing a special proprietary s
35、olvent rather thanacetone should not be used with poly vinyl chloride tubing asweakening of the tubing walls can cause a potentially hazard-ous situation.)12. Standardization12.1 Prepare 100 mL each of a blank and at least fourstandard solutions to bracket the expected iron concentrationrange of the
36、 samples to be analyzed by diluting the standardiron solution with HNO3(1 + 499). Prepare the standards eachtime the test is to be performed.12.2 When determining total recoverable iron add 0.5 mL ofHNO3(sp gr 1.42) and proceed as directed in 13.1 through13.5. When determining dissolved iron proceed
37、 as directed inNote 5, 13.1.12.3 Aspirate the blank and standards and record the instru-ment readings. Aspirate HNO3(1 + 499) between each stan-dard.12.4 Prepare an analytical curve by plotting the absorbanceversus concentration for each standard on linear graph paper.Alternatively read directly in
38、concentration if this capability isprovided with the instrument.13. Procedure13.1 Measure 100.0 mL of a well-mixed acidified sampleinto a 125-mL beaker or flask.NOTE 5If only dissolved iron is to be determined, start with 13.5.13.2 Add 5 mL of HCl (sp gr 1.19) to each sample.13.3 Heat the samples on
39、 a steam bath or hotplate in awell-ventilated hood until the volume has been reduced to 15to 20 mL, making certain that the samples do not boil.NOTE 6When analyzing samples of brines or samples containingappreciable amounts of suspended matter or dissolved solids, the amountof reduction in volume is
40、 left to the discretion of the analyst.13.4 Cool and filter the samples through a suitable filter(such as fine-textured, acid-washed, ashless paper), into100-mL volumetric flasks. Wash the filter paper two or threetimes with water and adjust a volume.13.5 Aspirate each filtered and acidified sample
41、and deter-mine its absorbance or concentration at 248.3 nm. AspirateHNO3(1 + 499) between each sample.14. Calculation14.1 Calculate the concentration of iron in the sample, inmilligrams per litre, referring to 12.4.15. Precision and Bias515.1 The precision of this test method for 10 laboratories,whi
42、ch include 16 operations within its designated range may beexpressed as follows:Reagent Water Type II:ST5 0.047 X 1 0.053So5 0.030 X 1 0.037Water of Choice:ST5 0.050 X 1 0.114So5 0.024 X 1 0.078where:ST= overall precision,So= single-operator precision, andX = determined concentration of iron, mg/L.1
43、5.2 Recoveries of known amounts of iron in a series ofprepared standards were as shown in Table 1.15.3 The collaborative test data were obtained on reagentwater; tap, lake, ground and surface water; unspecified waste-water; and a refinery primary treatment water. It is the usersresponsibility to ens
44、ure the validity of this test method forwaters of untested matrices.15.4 This section on precision and bias conforms to PracticeD277777which was in place at the time of collaborativetesting. Under the allowances made in 1.4 of D 2777 98,these precision and bias data do meet existing requirements ofi
45、nterlaboratory studies of Committee D19 test methods.16. Quality Control16.1 In order to be certain that analytical values obtainedusing these test methods are valid and accurate within the5Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research R
46、eport RR: D191035.TABLE 1 Determination of Bias, Atomic Absorption, DirectReagent Water Type II:Bias, %StatisticallySignificant(95 %ConfidenceLevel)Amount Added,mg/LAmount Found,mg/LBias, mg/L0.2 0.2 60.0 0.0 no2.4 2.4 60.0 0.0 no4.4 4.3 0.1 2.3 yesNatural Water:Bias, %StatisticallySignificant(95 %C
47、onfidenceLevel)Amount Added,mg/LAmount Found,mg/LBias, mg/L0.2 0.2 60.0 0 no2.4 2.3 0.1 4.17 yes4.4 4.2 0.2 4.55 yesD106805e13confidence limits of the test, the following QC procedures mustbe followed when analyzing iron.16.2 Calibration and Calibration Verification:16.2.1 Analyze at least three wor
48、king standards containingconcentrations of iron that bracket the expected sample con-centration, prior to analysis of samples, to calibrate theinstrument. The calibration correlation coefficient shall beequal to or greater than 0.990. In addition to the initialcalibration blank, a calibration blank
49、shall be analyzed at theend of the batch run to ensure contamination was not a problemduring the batch analysis.16.2.2 Verify instrument calibration after standardization byanalyzing a standard at the concentration of one of thecalibration standards. The concentration of a mid-range stan-dard should fall within 615 % of the known concentration.16.2.3 If calibration cannot be verified, recalibrate theinstrument.16.3 Initial Demonstration of Laboratory Capability:16.3.1 If a laboratory has not performed the test before, or ifthere has bee
