1、Designation: D 3558 08Standard Test Methods forCobalt in Water1This standard is issued under the fixed designation D 3558; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates
2、 the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope1.1 These test methods cover the determination of dissolvedand total recoverable cobalt i
3、n water and wastewater2byatomic absorption spectrophotometry. Three test methods areincluded as follows:Concentration Range SectionsTest Method AAtomic Absorption,Direct0.1to10mg/L 7 to 16Test Method BAtomic Absorption,Chelation-Extraction10 to 1000 g/L 17 to 26Test Method CAtomic Absorption,Graphit
4、e Furnace5 to 100 g/L 27 to 361.2 Test Method A has been used successfully with reagentwater, potable water, river water, and wastewater. Test MethodB has been used successfully with reagent water, potable water,river water, sea water and brine. Test Method C was success-fully evaluated in reagent w
5、ater, artificial seawater, river water,tap water, and a synthetic brine. It is the analysts responsibilityto ensure the validity of these test methods for other matrices.1.3 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.4 Th
6、is 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. For specific hazards
7、tatements, see 11.7.1, 21.10, and 23.10.2. Referenced Documents2.1 ASTM Standards:3D 858 Test Methods for Manganese in WaterD 1066 Practice for Sampling SteamD 1068 Test Methods for Iron in WaterD 1129 Terminology Relating to WaterD 1193 Specification for Reagent WaterD 1687 Test Methods for Chromiu
8、m in WaterD 1688 Test Methods for Copper in WaterD 1691 Test Methods for Zinc in WaterD 1886 Test Methods for Nickel in WaterD 2777 Practice for Determination of Precision and Bias ofApplicable Test Methods of Committee D19 on WaterD 3370 Practices for Sampling Water from Closed ConduitsD 3557 Test
9、Methods for Cadmium in WaterD 3559 Test Methods for Lead in WaterD 3919 Practice for Measuring Trace Elements in Water byGraphite Furnace Atomic Absorption SpectrophotometryD 4841 Practice for Estimation of Holding Time for WaterSamples Containing Organic and Inorganic ConstituentsD 5810 Guide for S
10、piking into Aqueous SamplesD 5847 Practice for Writing Quality Control Specificationsfor Standard Test Methods for Water Analysis3. Terminology3.1 Definitions:3.1.1 For definitions of terms used in these test methods,refer to Terminology D 1129.3.2 Definitions of Terms Specific to This Standard:3.2.
11、1 total recoverable cobaltan arbitrary analytical termrelating to the recoverable forms of cobalt that are determin-able by the digestion method which is included in the proce-dure.4. Significance and Use4.1 Most waters rarely contain more than trace concentra-tions of cobalt from natural sources.Al
12、though trace amounts ofcobalt seem to be essential to the nutrition of some animals,large amounts have pronounced toxic effects on both plant andanimal life.5. Purity of Reagents5.1 Reagent grade chemicals shall be used in all tests.Unless otherwise indicated, it is intended that all reagents shallc
13、onform to the specifications of the Committee on Analytical1These test methods are under the jurisdiction of ASTM Committee D19 onWater and are the direct responsibility of Subcommittee D19.05 on InorganicConstituents in Water.Current edition approved Nov. 15, 2008. Published November 2008. Original
14、lyapproved in 1977. Last previous edition approved in 2003 as D 3558 03.2Platte, J.A., and March, V. M., “ANew Tool for the Water Chemist,” IndustrialWater Engineering, May 1965.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org.
15、For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.Reagents of the American Chemical Society where suchspecifications a
16、re available.4Other grades may be used, pro-vided it is first ascertained that the reagent is of sufficientlyhigh purity to permit its use without lessening the accuracy ofthe determination.5.2 Unless otherwise indicated, reference to water shall beunderstood to mean reagent water conforming to Spec
17、ificationD 1193, Type I. Other reagent water types may be used,provided it is first ascertained that the water is of sufficientlyhigh purity to permit its use without lessening the bias andprecision of the determination. Type II water specified at thetime of the round-robin testing of this test meth
18、od.6. Sampling6.1 Collect the samples in accordance with PracticesD 3370 and Practice D 1066, as applicable.6.2 Preserve samples with HNO3(sp gr 1.42) to a pH of 2 orless immediately at the time of collection, normally about 2mL/L. If only dissolved cobalt is to be determined, filter thesample throu
19、gh a 0.45-m membrane filter before acidification.The holding time for samples may be calculated in accordancewith Practice D 4841.TEST METHOD AATOMIC ABSORPTION, DIRECT7. Scope7.1 This test method covers the determination of dissolvedand total recoverable cobalt in most waters and waste waters.It is
20、 the users responsibility to ensure the validity of this testmethod in a particular matrix.7.2 This test method is applicable in the range from 0.1 to10 mg/L of cobalt. The range may be extended to concentra-tions greater than 10 mg/L by dilution of the sample.8. Summary of Test Method8.1 Cobalt is
21、determined by atomic absorption spectropho-tometry. Dissolved cobalt is determined by aspirating a portionof the filtered sample directly with no pretreatment. Totalrecoverable cobalt is determined by aspirating the samplefollowing hydrochloric-nitric acid digestion and filtration. Thesame digestion
22、 procedure may be used to determine totalrecoverable nickel (Test Methods D 1886), chromium (TestMethods D 1687), cadmium (Test Methods D 3557), copper(Test Methods D 1688), iron (Test Methods D 1068), lead (TestMethods D 3559), manganese (Test Methods D 858), zinc(Test Methods D 1691).9. Interferen
23、ces9.1 Nitrate reportedly interferes at 1 mg/L by suppressingthe absorption of the cobalt. This interference can be elimi-nated by adding 18 000 mg/L of ammonium chloride toblanks, standards, and samples.9.2 Other metals usually do not interfere in the determina-tion of cobalt by increasing or decre
24、asing the amount ofabsorbed radiation. The most common interference is causedby a chemical reaction in the flame that prevents conversion ofthe cobalt to the atomic state.9.3 Sodium, potassium, and sulfate, magnesium (4500 mg/L), iron (4000 mg/L), and nickel, lead, copper, zinc, cadmium,and chromium
25、 (10 mg/L each) do not interfere.9.4 Background correction or a chelation-extraction proce-dure (see Test Method B) may be necessary to determine lowlevels of cobalt in some water.NOTE 1Instrument manufacturers instructions for use of the specificcorrection technique should be followed.10. Apparatus
26、10.1 Atomic Absorption Spectrophotometer, for use at 240.7nm.NOTE 2The manufacturers instructions should be followed for allinstrumental parameters. A wavelength other than 240.7 nm may be usedif it has been determined to be equally suitable.10.2 Cobalt Hollow-Cathode LampsMultielementhollow-cathode
27、 lamps.10.3 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 Materials11.1 Cobalt Solution, Stock (1 mL = 1.0 mg Co)Commercially purchase or dissolve 4.0
28、372 g of cobaltouschloride (CoCl26H2O) in reagent water and dilute to 1 L.11.2 Cobalt Solution, Standard (1 mL = 0.1 mg Co)Dissolve 100.0 mL of the stock cobalt solution to 1 L withwater.11.3 Hydrochloric Acid (sp gr 1.19)Concentrated hydro-chloric acid (HCl).NOTE 3If a high reagent blank is obtaine
29、d, distill the HCl or usespectrograde acid. When HCl is distilled, an azeotrophic mixture isobtained (approximately 6 N HCl is formed). Therefore, wheneverconcentrated HCl is specified for the preparation of a reagent or in theprocedure, use double the volume specified if distilled acid is used.11.4
30、 Nitric Acid (sp gr 1.42)Concentrated nitric acid(HNO3).NOTE 4If a high reagent blank is obtained, distill the HNO3or use aspectrograde acid.11.5 Nitric Acid (1 + 499)Add 1 volume of HNO3(sp gr1.42) to 499 volumes of water.11.6 Oxidant:11.6.1 Air, which has been passed through a suitable filter tore
31、move oil, water, and other foreign substances is the 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). (“Purified” gra
32、de acetylenecontaining a special proprietary solvent rather than acetone4Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For Suggestions on the testing of reagents notlisted by the American Chemical Society, see Annual Standards for LaboratoryCh
33、emicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.D3558082should not be used with poly(vinyl chloride) tubing as weak-ening of the tubing walls can cause a potentially hazardoussituation.12. Stan
34、dardization12.1 Prepare 100 mL each of a blank and at least fourstandard solutions to bracket the expected cobalt concentrationrange of the samples to be analyzed by diluting the standardcobalt solution (see 11.2) with HNO3(1 + 499). Prepare thestandards each time the test is to be performed.12.2 Wh
35、en determining total recoverable cobalt, add 0.5 mLof HNO3(sp gr 1.42) and proceed as directed in 13.2 through13.4. When determining dissolved cobalt, proceed with 12.3.12.3 Aspirate the blank and the standards and record theinstrument readings. Aspirate HNO3(1 + 499) between stan-dards.12.4 Prepare
36、 an analytical curve by plotting the absorbanceversus concentration for each standard on linear graph paper.Alternatively, read directly in 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
37、.NOTE 5If only dissolved cobalt is to be determined, proceed from13.5.13.2 Add 5 mL of HCl (sp gr 1.19) to each sample.13.3 Heat the samples on 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 6For sam
38、ples with high levels of suspended matter, the amountof reduction in volume is left to the discretion of the analyst.13.4 Cool and filter the samples through a suitable filter,such as fine-texture, acid-washed, ashless paper, into 100-mLvolumetric flasks. Wash the filter paper two or three times wit
39、hwater and bring to volume.13.5 Atomize each filtered and acidified sample and deter-mine its absorbance or concentration.Atomize HNO3(1 + 499)between samples.14. Calculation14.1 Calculate the concentration of cobalt in the sample, inmilligrams per litre, using an analytical curve or, alternatively,
40、read directly in concentration (see 12.4).15. Precision and Bias515.1 The single-operator and overall precision of this testmethod within its designated range for eleven laboratories,which include a total of sixteen operators (at 1.0, 4.0, and 8.0mg/L) analyzing each sample on three different days v
41、arieswith the quantity being tested in accordance with Fig. 1 andFig. 2.15.2 Recoveries of known amounts of cobalt in a series ofprepared standards for the same laboratories were as shown inTable 1.15.3 These precision and bias data may not apply to watersof different matrices. The waters used in ev
42、aluations werereagent water, potable water, river water, and wastewater. It isthe users responsibility to ensure the validity of this testmethod for waters of untested matrices.15.4 This section on precision and bias conforms to PracticeD 2777 77 which was in place at the time of collaborative5Suppo
43、rting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR: D19-1032.FIG. 1 Precision for Cobalt in Reagent Water, Type II by Direct Atomic AbsorptionD3558083testing. Under the allowances made in 1.4 of D 2777 06,these precision and bias data do
44、 meet existing requirements ofinterlaboratory 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 theconfidence limits of the test, the following QC procedures mustbe followed when
45、analyzing cobalt.16.2 Calibration and Calibration Verification16.2.1 Analyze at least four working standards containingconcentrations of cobalt that bracket the expected sampleconcentration, prior to analysis of samples, to calibrate theinstrument. The calibration correlation coefficient shall beequ
46、al to or greater than 0.990. In addition to the initialcalibration blank, a calibration blank 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 conce
47、ntration 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 Capability16.3.1 If a laboratory has not performed t
48、he test before, or ifthere has been a major change in the measurement system, forexample, new analyst, new instrument, and so forth, a precisionand bias study must be performed to demonstrate laboratorycapability.16.3.2 Analyze seven replicates of a standard solutionprepared from an Independent Refe
49、rence Material containing amidrange concentration of cobalt. The matrix and chemistry ofthe solution should be equivalent to the solution used in thecollaborative study. Each replicate must be taken through thecomplete analytical test method including any sample preser-vation and pretreatment steps.16.3.3 Calculate the mean and standard deviation of theseven values and compare to the acceptable ranges of bias inTable 1. This study should be repeated until the recoveries arewithin the limits given in Table 1. If a concentration other thanthe recommende
