1、Designation: D 3558 03Standard 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 (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.1. Scope*1.1 These test methods cover the determination of dissolvedand total recoverable cobalt
3、 in water and wastewater2byatomic absorption spectrophotometry. Three test methods areincluded as follows:Concentration Range SectionsTest Method AAtomic Absorption,Direct 0.1 to 10 mg/L 7 to 16Test Method BAtomic Absorption,Chelation-Extraction 10 to 1000 g/L 17 to 26Test Method CAtomic Absorption,
4、Graphite Furnace 5 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 r
5、eagent water, 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 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is therespons
6、ibility 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 hazardstatements, see 11.7.1, 21.10, and 23.10.2. Referenced Documents2.1 ASTM Standards:D 858 Test Methods for Manganese i
7、n Water3D 1066 Practice for Sampling Steam3D 1068 Test Methods for Iron in Water3D 1129 Terminology Relating to Water3D 1193 Specification for Reagent Water3D 1687 Test Methods for Chromium in Water3D 1688 Test Methods for Copper in Water3D 1691 Test Methods for Zinc in Water3D 1886 Test Methods for
8、 Nickel in Water3D 2777 Practice for Determination of Precision and Bias ofApplicable Methods of Committee D19 on Water3D 3370 Practices for Sampling Water from Closed Con-duits3D 3557 Test Methods for Cadmium in Water3D 3559 Test Methods for Lead in Water3D 3919 Practice for Measuring Trace Element
9、s in Water byGraphite Furnace Atomic Absorption Spectrophotometry3D 4841 Practice for Estimation of Holding Time for WaterSamples Containing Organic and Inorganic Constituents3D 5810 Guide for Spiking into Aqueous Samples3D 5847 Practice for Writing Quality Control Specificationsfor Standard Test Me
10、thods for Water Analysis43. 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:3.2.1 total recoverable cobaltan arbitrary analytical termrelating to the recoverable forms of cobalt that a
11、re 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.Although trace amounts ofcobalt seem to be essential to the nutrition of some animals,large amounts have p
12、ronounced 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 shallconform to the specifications of the Committee on Analytical1These test methods are under the jurisdictio
13、n of ASTM Committee D19 onWater and are the direct responsibility of Subcommittee D19.05 on InorganicConstituents in Water.Current edition approved June 10, 2003. Published July 2003. Originallyapproved in 1977. Last previous edition approved in 1998 as D 3558 94 (1998).2Platte, J.A., and March, V.
14、M., “ANew Tool for the Water Chemist,” IndustrialWater Engineering, May 1965.3Annual Book of ASTM Standards, Vol 11.01.4Annual Book of ASTM Standards, Vol 11.02.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West C
15、onshohocken, PA 19428-2959, United States.Reagents of the American Chemical Society where suchspecifications are available.5Other grades may be used,provided it is first ascertained that the reagent is of sufficientlyhigh purity to permit its use without lessening the accuracy ofthe determination.5.
16、2 Unless otherwise indicated, reference to water shall beunderstood to mean reagent water conforming to SpecificationD 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 andpre
17、cision of the determination. Type II water specified at thetime of the round-robin testing of this test method.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 ti
18、me of collection, normally about 2mL/L. If only dissolved cobalt is to be determined, filter thesample through 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 me
19、thod covers the determination of dissolvedand total recoverable cobalt in most waters and waste waters.It is 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 extend
20、ed to concentra-tions greater than 10 mg/L by dilution of the sample.8. Summary of Test Method8.1 Cobalt is determined by atomic absorption spectropho-tometry. Dissolved cobalt is determined by aspirating a portionof the filtered sample directly with no pretreatment. Totalrecoverable cobalt is deter
21、mined by aspirating the samplefollowing hydrochloric-nitric acid digestion and filtration. Thesame digestion 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
22、 D 1068), lead (TestMethods D 3559), manganese (Test Methods D 858), zinc(Test Methods D 1691).9. Interferences9.1 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,
23、and samples.9.2 Other metals usually do not interfere in the determina-tion of cobalt by increasing or decreasing 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
24、, and sulfate, magnesium (4500 mg/L), iron (4000 mg/L), and nickel, lead, copper, zinc, cadmium,and chromium (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 1Instru
25、ment manufacturers instructions for use of the specificcorrection technique should be followed.10. Apparatus10.1 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 use
26、dif it has been determined to be equally suitable.10.2 Cobalt Hollow-Cathode LampsMultielementhollow-cathode 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.1
27、1. Reagents and Materials11.1 Cobalt Solution, Stock (1 mL = 1.0 mg Co)Dissolve4.0372 g of cobaltous chloride (CoCl26H2O) in reagent waterand 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
28、.19)Concentrated hydro-chloric acid (HCl).NOTE 3If a high reagent blank is obtained, 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
29、or in theprocedure, use double the volume specified if distilled acid is used.11.4 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 w
30、ater.11.6 Oxidant:11.6.1 Air, which has been passed through a suitable filter toremove 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 analyt
31、ical results. The cylinder should bereplaced at 50 psig (345 kPa). (Warning“Purified” gradeacetylene containing a special proprietary solvent rather than5Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents
32、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. Pharmaceutical Convention, Inc. (USPC), Rockville,MD.D 3558 032acetone should not be used with poly(vinyl chloride)
33、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 cobalt concentrationrange of the samples to be analyzed by diluting the standardcobalt solution (see
34、 11.2) with HNO3(1 + 499). Prepare thestandards each time the test is to be performed.12.2 When 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 standa
35、rds and record theinstrument readings. Aspirate HNO3(1 + 499) between stan-dards.12.4 Prepare 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.
36、 Procedure13.1 Measure 100.0 mL of a well-mixed acidified sampleinto a 125-mL beaker or flask.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 vol
37、ume has been reduced to 15to 20 mL, making certain that the samples do not boil.NOTE 6For samples 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-wash
38、ed, ashless paper, into 100-mLvolumetric flasks. Wash the filter paper two or three times withwater 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
39、of cobalt in the sample, inmilligrams per litre, using an analytical curve or, alternatively,read directly in concentration (see 12.4).15. Precision and Bias615.1 The single-operator and overall precision of this testmethod within its designated range for eleven laboratories,which include a total of
40、 sixteen operators (at 1.0, 4.0, and 8.0mg/L) analyzing each sample on three different days varieswith 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 Thes
41、e precision and bias data may not apply to watersof different matrices. The waters used in evaluations 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
42、 and bias conforms to PracticeD 2777 77 which was in place at the time of collaborative6Supporting data have been filed at ASTM International Headquarters and maybe obtained by requesting Research Report RR: D191032.FIG. 1 Precision for Cobalt in Reagent Water, Type II by Direct Atomic AbsorptionD 3
43、558 033testing. Under the allowances made in 1.4 of D 2777 98,these precision and bias data do 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 accur
44、ate within theconfidence limits of the test, the following QC procedures mustbe followed when analyzing cobalt.16.2 Calibration and Calibration Verification16.2.1 Analyze at least three working standards containingconcentrations of cobalt that bracket the expected sampleconcentration, prior to analy
45、sis 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 shall be analyzed at theend of the batch run to ensure contamination was not a problemduring the batch analysis
46、.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 theinstrumen
47、t.16.3 Initial Demonstration of Laboratory Capability16.3.1 If a laboratory has not performed the 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 laboratorycap
48、ability.16.3.2 Analyze seven replicates of a standard solutionprepared from an Independent Reference 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 throug
49、h thecomplete analytical test method including any sample preser-vation and pretreatment steps. The replicates may be inter-spersed with samples.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 recommended concentration is used, refer to PracticeD5847 for information on applying the F test and t test inevaluating the acceptability of the mean and standard
