1、Designation: D3558 08D3558 15Standard Test Methods forCobalt in Water1This standard is issued under the fixed designation D3558; 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 ind
2、icates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope Scope*1.1 These test methods cover the determination of dissolved and total recoverable cobalt in water and wastewater 2 by atomicabsorption spectrophotometry. Thr
3、ee test methods are included as follows:Concentration Range SectionsTest Method AAtomic Absorption,Direct0.1 to 10 mg/L 7 to 16Test Method BAtomic Absorption,Chelation-Extraction10 to 1000 g/L 17 to 26Test Method CAtomic Absorption,Graphite Furnace5 to 100 g/L 27 to 36Concentration Range SectionsTes
4、t Method AAtomic Absorption,Direct0.1 to 10 mg/L 7 to 16Test Method BAtomic Absorption,Chelation-Extraction10 to 1000 g/L 17 to 26Test Method CAtomic Absorption,Graphite Furnace5 to 100 g/L 27 to 361.2 Test Method A has been used successfully with reagent water, potable water, river water, and waste
5、water. Test Method Bhas been used successfully with reagent water, potable water, river water, sea water and brine. Test Method C was successfullyevaluated in reagent water, artificial seawater, river water, tap water, and a synthetic brine. It is the analysts responsibility to ensurethe validity of
6、 these test methods for other matrices.1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this The valuesgiven in parentheses are mathematical conversions to inch-pound units that are provided for information only and are notconsidered sta
7、ndard.1.4 This standard does not purport to address 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 specif
8、ic hazard statements, see 11.7.111.8.1, 21.1021.12, and 23.10.2. Referenced Documents2.1 ASTM Standards:3D858 Test Methods for Manganese in WaterD1066 Practice for Sampling SteamD1068 Test Methods for Iron in WaterD1129 Terminology Relating to WaterD1193 Specification for Reagent WaterD1687 Test Met
9、hods for Chromium in WaterD1688 Test Methods for Copper in WaterD1691 Test Methods for Zinc in WaterD1886 Test Methods for Nickel in WaterD2777 Practice for Determination of Precision and Bias of Applicable Test Methods of Committee D19 on Water1 These test methods are under the jurisdiction of ASTM
10、 Committee D19 on Water and are the direct responsibility of Subcommittee D19.05 on Inorganic Constituentsin Water.Current edition approved Nov. 15, 2008Feb. 1, 2015. Published November 2008March 2015. Originally approved in 1977. Last previous edition approved in 20032008as D3558 03.D3558 08. DOI:
11、10.1520/D3558-08.10.1520/D3558-15.2 Platte, J. A., and March, V. M., “A New Tool for the Water Chemist,” Industrial Water Engineering, May 1965.3 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvo
12、lume information, refer to the standards Document Summary page on the ASTM website.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 version. Becauseit may not be technically possible to ade
13、quately 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 section appears at the end of this standardCopyright ASTM
14、 International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1D3370 Practices for Sampling Water from Closed ConduitsD3557 Test Methods for Cadmium in WaterD3559 Test Methods for Lead in WaterD3919 Practice for Measuring Trace Elements in Water by Graphite Furna
15、ce Atomic Absorption SpectrophotometryD4841 Practice for Estimation of Holding Time for Water Samples Containing Organic and Inorganic ConstituentsD5673 Test Method for Elements in Water by Inductively Coupled PlasmaMass SpectrometryD5810 Guide for Spiking into Aqueous SamplesD5847 Practice for Writ
16、ing Quality Control Specifications for Standard Test Methods for Water Analysis3. Terminology3.1 Definitions:3.1.1 For definitions of terms used in these test methods, refer to Terminology D1129.3.2 Definitions of Terms Specific to This Standard:3.2.1 total recoverable cobaltcobalt, nan arbitrary an
17、alytical a descriptive term relating to the recoverable forms of cobaltthat are determinable by the digestion method which is included in the procedure. cobalt forms recovered in the acid-digestionprocedure specified in these test methods.4. Significance and Use4.1 Most waters rarely contain more th
18、an trace concentrations of cobalt from natural sources.Although trace amounts of cobaltseem to be essential to the nutrition of some animals, large amounts have pronounced toxic effects on both plant and animal life.5. Purity of Reagents5.1 Reagent grade chemicals shall be used in all tests. Unless
19、otherwise indicated, it is intended that all reagents shall conformto the specifications of the Committee on Analytical Reagents of the American Chemical Society where such specifications areavailable.4 Other grades may be used, provided it is first ascertained that the reagent is of sufficiently hi
20、gh purity to permit its usewithout lessening the accuracy of the determination.5.2 Unless otherwise indicated, reference to water shall be understood to mean reagent water conforming to SpecificationD1193, Type I. Other reagent water types may be used, provided it is first ascertained that the water
21、 is of sufficiently high purityto permit its use without lessening the bias and precision of the determination.Type II water specified at the time of the round-robintesting of this test method.6. Sampling6.1 Collect the samples in accordance with Practices D3370 and Practice D1066, as applicable.6.2
22、 Preserve samples with HNO3 (sp gr 1.42) to a pH of 2 or less immediately at the time of collection, normally about 2 mL/L.If only dissolved cobalt is to be determined, filter the sample through a 0.45-m membrane filter before acidification. The holdingtime for samples may be calculated in accordanc
23、e with Practice D4841.NOTE 1Alternatively, the pH may be adjusted in the laboratory if the sample is returned within 14 days. However, acid must be added at least 24hours before analysis to dissolve any metals that adsorb to the container walls. This could reduce hazards of working with acids in the
24、 field whenappropriate.TEST METHOD AATOMIC ABSORPTION, DIRECT7. Scope7.1 This test method covers the determination of dissolved and total recoverable cobalt in most waters and waste waters. It isthe users responsibility to ensure the validity of this test method in a particular matrix.7.2 This test
25、method is applicable in the range from 0.1 to 10 mg/L of cobalt. The range may be extended to concentrationsgreater than 10 mg/L by dilution of the sample.8. Summary of Test Method8.1 Cobalt is determined by atomic absorption spectrophotometry. Dissolved cobalt is determined by aspirating a portion
26、of thefiltered sample directly with no pretreatment. Total recoverable cobalt is determined by aspirating the sample followinghydrochloric-nitric acid digestion and filtration. The same digestion procedure may be used to determine total recoverable nickel4 Reagent Chemicals, American Chemical Societ
27、y Specifications, American Chemical Society, Washington, DC. For Suggestions on the testing of reagents not listed bythe American Chemical Society, see Annual Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia and NationalFormulary, U.S. Pharmacopei
28、al Convention, Inc. (USPC), Rockville, MD.D3558 152(Test Methods D1886), chromium (Test Methods D1687), cadmium (Test Methods D3557), copper (Test Methods D1688), iron(Test Methods D1068), lead (Test Methods D3559), manganese (Test Methods D858), zinc (Test Methods D1691).9. Interferences9.1 Nitrate
29、 reportedly interferes at 1 mg/L by suppressing the absorption of the cobalt. This interference can be eliminated byadding 18 000 mg/L of ammonium chloride to blanks, standards, and samples.9.2 Other metals usually do not interfere in the determination of cobalt by increasing or decreasing the amoun
30、t of absorbedradiation. The most common interference is caused by a chemical reaction in the flame that prevents conversion of the cobalt tothe atomic state.9.3 Sodium, potassium, and sulfate, magnesium (4500 mg/L), iron (4000 mg/L), and nickel, lead, copper, zinc, cadmium, andchromium (10 mg/L each
31、) do not interfere.9.4 Background correction or a chelation-extraction procedure (see Test Method B) may be necessary to determine low levelsof cobalt in some water.NOTE 2Instrument manufacturers instructions for use of the specific correction technique should be followed.10. Apparatus10.1 Atomic Ab
32、sorption Spectrophotometer, for use at 240.7 nm.NOTE 3The manufacturers instructions should be followed for all instrumental parameters. A wavelength other than 240.7 nm may be used if it hasbeen determined to be equally suitable.10.2 Cobalt Hollow-Cathode LampsMultielement hollow-cathode lamps.10.3
33、 Pressure-Reducing ValvesThe supplies of fuel and oxidant shall be maintained at pressures somewhat higher than thecontrolled operating pressure of the instrument by suitable valves.11. Reagents and Materials11.1 Cobalt Solution, Stock (1 mL = 1.0 mg Co)Commercially purchase or dissolve 4.0372 g of
34、cobaltous chloride(CoCl26H2O) in reagent water and dilute to 1 L.Apurchased cobalt stock solution of appropriate known purity is also acceptable.11.2 Cobalt Solution, Standard (1 mL = 0.1 mg Co)DissolveDilute 100.0 mL of the stock cobalt solution to 1 L with water.11.3 Filter PaperPurchase suitable
35、filter paper. Typically the filter papers have a pore size of 0.45-m membrane. Materialsuch as fine-textured, acid-washed, ashless paper, or glass fiber paper are acceptable. The user must first ascertain that the filterpaper is of sufficient purity to use without adversely affecting the bias and pr
36、ecision of the test method.11.4 Hydrochloric Acid (sp gr 1.19)Concentrated hydrochloric acid (HCl).NOTE 4If a high reagent blank is obtained, distill the HCl or use spectrograde acid. When HCl is distilled, an azeotrophic mixture is obtained(approximately 6 N HCl is formed). Therefore, whenever conc
37、entrated HCl is specified for the preparation of a reagent or in the procedure, use doublethe volume specified if distilled acid is used.11.5 Nitric Acid (sp gr 1.42)Concentrated nitric acid (HNO3).NOTE 5If a high reagent blank is obtained, distill the HNO3 or use a spectrograde acid.11.6 Nitric Aci
38、d (1 + 499)Add 1 volume of HNO3 (sp gr 1.42) to 499 volumes of water.11.7 Oxidant:11.7.1 Air, which has been passed through a suitable filter to remove oil, water, and other foreign substances is the usual oxidant.11.8 Fuel:11.8.1 AcetyleneStandard, commercially available acetylene is the usual fuel
39、. Acetone, always present in acetylene cylinderscan affect analytical results. The cylinder should be replaced at 50 psig (345 kPa).345 kPa (50 psi). (“Purified” grade acetylenecontaining a special proprietary solvent rather than acetone should not be used with poly(vinyl chloride) tubing as weakeni
40、ng ofthe tubing walls can cause a potentially hazardous situation.situation.)12. Standardization12.1 Prepare 100 mL each of a blank and at least four standard solutions to bracket the expected cobalt concentration range ofthe samples to be analyzed by diluting the standard cobalt solution (see 11.2)
41、 with HNO3 (1 + 499). Analyze at least four workingstandards containing concentrations of cobalt that bracket the expected sample concentration, prior to analysis of samples, tocalibrate the instrument. Prepare the standards each time the test is to be performed.performed or as determined by Practic
42、e D4841.12.2 When determining total recoverable cobalt, add 0.5 mLof HNO3 (sp gr 1.42) (11.5) and proceed as directed in 13.2 through13.4. When determining dissolved cobalt, proceed with 12.3.D3558 15312.3 Aspirate the blank and the standards and record the instrument readings. Aspirate HNO3 (1 + 49
43、9) between standards.12.4 Prepare an analytical curve by plotting the absorbance versus concentration for each standard on linear graph paper.Alternatively, read directly in concentration if this capability is provided with the instrument.13. Procedure13.1 Measure 100.0 mL of a well-mixed acidified
44、sample into a 125-mL beaker or flask.NOTE 6If only dissolved cobalt is to be determined, proceed from 13.5.13.2 Add 5 mL of HCl (sp gr 1.19) (11.4) to each sample.13.3 Heat the samples on a steam bath or hotplate in a well-ventilated hood until the volume has been reduced to 15 to 20 mL,making certa
45、in that the samples do not boil.NOTE 7For samples with high levels of suspended matter, the amount of reduction in volume is left to the discretion of the analyst.NOTE 8Many laboratories have found block digestion systems a useful way to digest samples for trace metals analysis. Systems typically co
46、nsist ofeither a metal or graphite block with wells to hold digestion tubes. The block temperature controller must be able to maintain uniformity of temperatureacross all positions of the block. For trace metals analysis, the digestion tubes should be constructed of polypropylene and have a volume a
47、ccuracy ofat least 0.5 %. All lots of tubes should come with a certificate of analysis to demonstrate suitability for their intended purpose.13.4 Cool and filter the samples through a suitable filter, filter (11.3), such as fine-texture, acid-washed, ashless paper, into100-mL volumetric flasks. Wash
48、 the filter paper two or three times with water and bring to volume.13.5 Atomize each filtered and acidified sample and determine its absorbance or concentration. Atomize HNO3 (1 + 499)between samples.14. Calculation14.1 Calculate the concentration of cobalt in the sample, in milligrams per litre, u
49、sing an analytical curve or, alternatively, readdirectly in concentration (see 12.4).15. Precision and Bias515.1 The single-operator and overall precision of this test method within its designated range for eleven laboratories, whichinclude a total of sixteen operators (at 1.0, 4.0, and 8.0 mg/L) analyzing each sample on three different days varies with the quantitybeing tested in accordance with Fig. 1 and Fig. 2.5 Supporting data have been filed at ASTM International Headquarters and may be obtained by requesting Research Report RR:D19-1
