1、Designation: D3866 07D3866 12Standard Test Methods forSilver in Water1This standard is issued under the fixed designation D3866; 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 atomic absorption determination of silver in water. Three test methods are given as follows:ConcentrationRange SectionsTest
3、Method AAtomic Absorp-tionChelation-ExtractionA1 to 10 g/L 7 to 15Test Method BAtomic Absorp-tionDirect0.1 to 10 mg/L 16 to 24Test Method CAtomic Absorp-tionGraphite Furnace1 to 25 g/L 25 to 33A SimilartothatinBrown,E.,Skougstad,M.W.,andFishman,M.J.,“MethodsforCollectionandAnalysisofWaterSamplesforD
4、issolvedMineralsandGases,”Techniquesof Water-Resources Investigations of the U.S. Geological Survey, Book 5, Chapter A1, 1970, p. 46.1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in eachsystem are mathematical conversions an
5、d may not be exact equivalents; therefore, each system shall be used independently of theother.1.3 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 pr
6、actices and determine the applicability of regulatorylimitations prior to use. Specific precautionary statements are given in Note 34, Note 56, Note 911, and Note 1315.2. Referenced Documents2.1 ASTM Standards:2D1129 Terminology Relating to WaterD1193 Specification for Reagent WaterD2777 Practice fo
7、r Determination of Precision and Bias of Applicable Test Methods of Committee D19 on WaterD3370 Practices for Sampling Water from Closed ConduitsD3919 Practice for Measuring Trace Elements in Water by Graphite Furnace Atomic Absorption SpectrophotometryD4691 Practice for Measuring Elements in Water
8、by Flame Atomic Absorption SpectrophotometryD4841 Practice for Estimation of Holding Time for Water Samples Containing Organic and Inorganic ConstituentsD5810 Guide for Spiking into Aqueous SamplesD5847 Practice for Writing Quality Control Specifications for Standard Test Methods for Water Analysis3
9、. Terminology3.1 Definition of Term Specific to These Test Methods:3.1.1 laboratory control sample, na solution with a certified concentration of silver.3.1.2 total recoverable silversilver, nan arbitrary analytical term relating to forms of silver that are determinable by thedigestion method that i
10、s included in the procedures.3.2 DefinitionsFor definition of terms used in these test methods, refer to Terminology D1129.1 These test methods are under the jurisdiction of ASTM Committee D19 on Water and are the direct responsibility of Subcommittee D19.05 on Inorganic Constituentsin Water.Current
11、 edition approved Aug. 1, 2007Sept. 1, 2012. Published August 2007September 2012. Originally approved in 1979. Last previous edition approved in 20022007as D3866 02.D3866 07. DOI: 10.1520/D3866-07.10.1520/D386612.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Cus
12、tomer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume 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 t
13、he previous version. 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
14、 of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States14. Significance and Use4.1 The principal adverse effect of silver in the body is cosmetic. It causes argyria, a permanent, blue-gra
15、y discoloration of theskin, eyes, and mucous membranes.4.2 Relatively small quantities of silver are bactericidal or bacteriostatic and find limited use in both disinfection of swimmingpool waters and point-of-use water filters.5. Purity of Reagents5.1 Reagent grade chemicals shall be used in all te
16、sts. Unless otherwise indicated, it is intended that all reagents shall conformto the specifications of the Committee on Analytical Reagents of the American Chemical Society, when such specifications areavailable.3 Other grades may be used, provided it is first ascertained that the reagent is of suf
17、ficiently high purity to permit its usewithout lessening the accuracy of the determination.5.2 Purity of WaterUnless otherwise indicated, references to water shall be understood to mean reagent water conforming toSpecification D1193, Type I, II, or III water. Type I is preferred and more commonly us
18、ed. Other reagent water types may be usedprovided it is first ascertained that the water is of sufficiently high purity to permit its use without adversely affecting the precisionand bias of the test method. Type II water was specified at the time of round robin testing of these test methods.NOTE 1T
19、he user must ensure the type of reagent water chosen is sufficiently free of interferences.The water should be analyzed using the test method.6. Sampling6.1 Collect the sample in accordance with Practices D3370. The holding time for the samples may be calculated in accordancewith Practice D4841.6.2
20、Preserve samples for Test Method A with HNO3 (sp gr 1.42) to a pH of 2 or less immediately at the time of collection;normally about 2 mL/L is required. If only dissolved silver is to be determined, filter the sample at time of collection through a0.45-m membrane filter before acidification.NOTE 2Alt
21、ernatively, the pH may be adjusted in the laboratory if the sample is returned within 14 days. This could reduce hazards of working withacids in the field when appropriate.6.3 Do not preserve samples for Test Methods B and C at the time of collection. If only dissolved silver is to be determined,fil
22、ter the sample through a 0.45-m membrane filter at time of collection. Add cyanogen iodide (CNI) solution to the samples inthe laboratory prior to analysis. For total recoverable silver it is preferable to add the cyanogen iodide to the entire sample to avoida nonhomogeneous solution; therefore, it
23、is advisable to collect a discrete sample for silver.TEST METHOD AATOMIC ABSORPTIONCHELATION EXTRACTION7. Scope7.1 This test method4 covers the determination of dissolved and total recoverable silver in most water and wastewaters.7.2 This test method is applicable in the range from 1 to 10 g/Lof sil
24、ver. The range may be extended by dilution of the originalsample.7.3 This test method has been used successfully with reagent water, natural surface water, and drinking water. The informationon precision and bias may not apply to other waters. It is the users responsibility to ensure the validity of
25、 this test method forwaters of untested matrices.8. Summary of Test Method8.1 Silver is determined by atomic absorption spectrometry. The element, either dissolved or total recoverable, is chelated withammonium pyrrolidine dithiocarbamate (APDC) and extracted with methyl isobutyl ketone (MIBK). The
26、extract is aspirated intoan air-acetylene flame of the spectrophotometer. Total recoverable silver is determined following nitric acid digestion and filtration.9. Interferences9.1 Concentrations of iron greater than 25 mg/L interfere by suppressing the silver absorption.10. Apparatus10.1 Atomic Abso
27、rption Spectrophotometer for use at 328.1 nm. A general guide for the use of flame atomic absorptionapplications is given in Practice D4691.3 Reagent Chemicals, American Chemical Society Specifications, American Chemical Society, Washington, DC. For Suggestions on the testing of reagents not listed
28、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. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.4 Similar to that in Brown, E., Skougstad, M. W., and Fishman, M. J., “Me
29、thods for Collection and Analysis of Water Samples for Dissolved Minerals and Gases,”Techniques of Water - Resources Investigations of the U.S. Geological Survey, Book 5, Chapter A1, 1970, p. 46.D3866 122NOTE 3The manufacturers instructions should be followed for instrumental parameters. Wave-length
30、s other than 328.1 nm may be used if they havebeen determined to be equally suitable.10.2 Silver Hollow-Cathode Lamp.10.3 Pressure-Reducing ValvesThe supplies of fuel and oxidant shall be maintained at pressures somewhat higher than thecontrolled operating pressure of the instrument by suitable pres
31、sure-reducing valves.11. Reagents and Materials11.1 Ammonium Pyrrolidine Dithiocarbamate (APDC) Solution(1 g/100 mL)Dissolve 1.0 g of APDC in 100 mL of water.Prepare fresh before each use.11.2 Bromophenol Blue Indicator Solution (0.1 g/100 mL)Dissolve 0.1 g of bromophenol blue in 100 mL of 50 % etha
32、nolor isopropanol.11.3 Hydrochloric Acid (sp gr 1.19)Concentrated hydrochloric acid (HCl).11.4 Hydrochloric Acid (1 + 49)Add 1 volume of hydrochloric acid (HCl, sp gr 1.19) to 49 volumes of water.11.5 Methyl Isobutyl Ketone (MIBK).NOTE 4Warning: Avoid inhalation and conduct all manipulation in a wel
33、l-ventilated hood.11.6 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.11.7 Silver Solution, Stock (1.0 mL = 100 g Ag)Crush approximately 2 g of silver nitrate (AgNO3) crystals and dry toconstant mass at 4
34、0C. Dissolve 0.1575 g ofAgNO3 in water containing 5 mL of concentrated HNO3 and dilute to 1000 mL. Storein an amber glass bottle. A purchased silver stock solution of appropriate known purity is also acceptable.11.8 Silver Solution, Intermediate (1.0 mL = 1.00 g Ag)Dilute 10.0 mL of silver stock sol
35、ution and 5 mL of concentratedHNO3 to 1000 mL with water. Store in an amber glass bottle. A purchased stock solution of adequate purity is also acceptable.11.9 Silver Solution, Standard (1.0 mL = 0.100 gAg)Dilute 100 mLof silver intermediate solution and 5 mLof concentratedHNO3 to 1000 mL with water
36、. Prepare fresh before use.11.10 Sodium Hydroxide Solution (100 g/L)Dissolve 100 g of NaOH in water and dilute to 1000 mL.11.11 Oxidant:11.11.1 Air, that has been passed through a suitable filter to remove oil, water, and other foreign substances is the usual oxidant.11.12 Fuel:11.12.1 Acetylene-Sta
37、ndard, commercially available acetylene is the usual fuel.Acetone, always present in acetylene cylinders,can affect analytical results. The cylinder should be replaced at 50 psig (345 kPa).345 kPa (50 psi). ( Warning, see Note 56.)NOTE 6Warning: “Purified” grade acetylene containing a special propri
38、etary solvent rather than acetone must not be used with poly(vinyl chloride)tubing as weakening of the tubing walls causes a potentially hazardous situation.12. Standardization12.1 Prepare a blank and sufficient standards containing from 0.0 to 1.0 g of silver by diluting 0.0 to 10.0-mLportions of s
39、ilverstandard solution to approximately 100 mL.12.2 To determine total recoverable silver, use 125-mL beakers or flasks, add 5.0 mL of HNO3 (sp gr 1.42), and proceed asdirected in 13.3 through 13.10. To determine dissolved silver use 200-mLvolumetric flasks and proceed as directed in 13.5 through13.
40、10. Treat the blank and each standard in the same manner as the samples.TABLE 1 Determination of Bias and Precision for Test Method AAmountAdded,g/LAgAmountFound,g/LAgBias,%StatisticallySignificant,95 %ConfidenceLevelOverallPrecision,StDegrees ofFreedomReagent Water, Type II2.0 2.18 + 9.0 no 0.77 75
41、.0 5.15 + 3.0 no 1.34 78.0 8.08 + 1.0 no 1.86 7Natural Water of Choice2.0 2.37 + 18.5 yes 0.74 75.0 4.99 0.2 no 0.92 78.0 8.38 + 4.8 no 2.21 7D3866 12312.3 Construct an analytical curve by plotting the absorbances of standards versus micrograms of silver. Alternatively, readdirectly in concentration
42、 if this capability is provided with the instrument.13. Procedure13.1 Measure a volume of a well-mixed acidified sample containing less than 1.0 g of silver (100-mL maximum) into a125-mL beaker or flask and adjust the volume to 100 mL with water.NOTE 7If only dissolved silver is to be determined, me
43、asure a volume of filtered and acidified sample containing less than 1.0 g of silver (100 mLmaximum) into a 200-mL volumetric flask and adjust the volume to 100 mL and start with 13.5.13.2 Add 5 mL of HNO3 (sp gr 1.42) (11.6) to each sample.13.3 Heat the samples on a steam bath or hot plate in a wel
44、l-ventilated hood until the volume has been reduced to 15 to 20 mLmaking certain that the samples do not boil.NOTE 8For brines and samples with a high concentration of suspended matter, the amount of reduction in volume is left to the discretion of theanalyst.NOTE 9Many laboratories have found block
45、 digestion systems a useful way to digest samples for trace metals analysis. Systems typically consist 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 trac
46、e metals analysis, the digestion tubes should be constructed of polypropylene and have a volume accuracy 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 each sample through a filter (such as a fi
47、ne-textured acid washed, ashless paper) into a 200-mL volumetricflask. Wash the filter paper two or three times with water and adjust the filtrate to about 100 mL.13.5 Add 2 drops of bromophenol blue indicator solution (11.2) and mix.13.6 Adjust the pH by addition of NaOH solution (100 g/L) (11.10)
48、until a blue color persists.Add HCl (1 + 49) (11.4) by dropsuntil the blue color just disappears; then add 2.5 mL of HCl (1 + 49) (11.4) in excess. The pH at this point should be 2.3.NOTE 10The pH adjustment in 13.6 may be made with a pH meter instead of using indicator.13.7 Add 2.5 mL of APDC solut
49、ion (11.1) and mix. The pH should be approximately 2.8.13.8 Add 10.0 mL of MIBK (11.5) and shake vigorously for 1 min.NOTE 11Warning: Perform in a well ventilated hood (see Note 34).13.9 Allow the layers to separate and add, carefully down the side of the flask, water until the ketone layer is completely in theneck of the flask.NOTE 12MIBK is soluble to some extent in water; therefore avoid any undue agitation of the solution during and after addition of water which couldresult in a concentration of the metal chelate in the
