1、Designation: D4698 92 (Reapproved 2013)Standard Practice forTotal Digestion of Sediment Samples for Chemical Analysisof Various Metals1This standard is issued under the fixed designation D4698; the number immediately following the designation indicates the year oforiginal adoption or, in the case of
2、 revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This practice covers two procedures for the total diges-tion of sediments for subsequent determ
3、ination of metals bysuch techniques as flame atomic absorption spectrophotometry,graphite-furnace atomic absorption spectrophotometry, atomicemission spectroscopy, etc.1.2 This practice is applicable in the subsequent determina-tion of volatile, semivolatile, and nonvolatile metals of sedi-ments.1.3
4、 Actual metal quantitation can be accomplished by fol-lowing the various test methods outlined under other appropri-ate ASTM standards for the metal(s) of interest. Beforeselecting either of the digestion techniques outlined in thispractice, the user should consult the appropriate quantitationstanda
5、rd(s) for any special analytical considerations, and Prac-tice D3976 for any special preparatory considerations.1.4 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 saf
6、ety and health practices and determine the applica-bility of regulatory limitations prior to use. For a specifichazard statement, see Note 7.1.5 The values stated in inch-pound units are to be regardedas the standard. The values given in parentheses are forinformation only.2. Referenced Documents2.1
7、 ASTM Standards:2D1129 Terminology Relating to WaterD1192 Guide for Equipment for Sampling Water and Steamin Closed Conduits (Withdrawn 2003)3D1193 Specification for Reagent WaterD3976 Practice for Preparation of Sediment Samples forChemical Analysis3. Terminology3.1 DefinitionsFor definitions of te
8、rms used in thispractice, refer to Terminology D1129.3.2 Definitions of Terms Specific to This Standard:3.2.1 total digestionthe dissolution of a sediment matrixsuch that quantitation will produce a measurement which ismore than 95 % of the constituent present in the sample.3.2.2 partial digestionth
9、e dissolution of a sediment matrixsuch that quantitation will produce a measurement of less than95 % of the constituent present in the sample. In such cases,recovery is operationally defined by the digestion procedure.4. Summary of Practice4.1 Many procedures are available for the total digestion of
10、sediments prior to metal analysis, but almost all the methodsfall into one of two main classes: fusion and subsequentdissolution of the bead, and wet digestion which directlydissolves the sample with mineral acids. Each of the classeshas advantages and disadvantages, as do the individual proce-dures
11、 which fall under them. The two procedures outlined inthis practice were selected because they are the least restricted,in terms of utility, for dealing with a wide variety of matrices.Before choosing a particular method, the user should consultthe pertinent literature to determine the utility and a
12、pplicabilityof either method, prior to final selection; or if a less rigorousdigestion could be employed.4,5 ,6,7Even then, experience witha particular sample type or digestion test method, or both, mayhave to be the final arbiter in test method selection.1This practice is under the jurisdiction of
13、ASTM Committee D19 on Water andis the direct responsibility of Subcommittee D19.07 on Sediments, Geomorphology,and Open-Channel Flow.Current edition approved Jan. 1, 2013. Published January 2013. Originallyapproved in 1987. Last previous edition approved in 2007 as D4698 92 (2007).DOI: 10.1520/D4698
14、-92R13.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3The last approved version of this historical standard
15、 is referenced onwww.astm.org.4Johnson, W., and Maxwell, J., Rock and Mineral Analysis , 2nd Edition, JohnWiley dislodge the beads by gentle tapping or with a spatula.NOTE 3The beads can be dissolved immediately after cooling, or canbe stored in plastic vials for dissolution at a later time.10.10 Pl
16、ace the bead in an acid-washed 250-mL plasticbottle and add a34 to 1 in. (19.05 to 25.4 mm) magnetic stirringbar. Add approximately 50-mL boiling water using a plasticgraduate, place the bottle on a magnetic stirrer, and mix. Add5mLofHNO3(1 + 1) to each bottle and stir rapidly for about60 min. Cap t
17、he bottle lightly to prevent both contaminationand possible spattering.10.11 Immediately after 60 min, remove the bottles from thestirrers, and add about 100 mL of water to prevent thepolymerization of silica.NOTE 4The solutions may contain small amounts of graphite from thecrucibles which can be ig
18、nored. However, if the solution is cloudy, thisindicates a very high concentration of silica in the original sample and thatit has polymerized. Such a solution must be discarded, and a new fusionperformed using a smaller quantity of sample.10.12 Pour each solution into a 200-mL volumetric flask,usin
19、g a funnel, in order to retain the stirring bar. Rinse thebottle and cap, and bring to the mark with water. Pour thesolution back into the plastic bottle for storage.10.13 Add 10 mL of CsCl solution and 20 mL of H3BO3solution to each bottle.NOTE 5The CsCl acts as an ionization suppressant and the H3
20、BO3stabilizes the silica; these are used when quantitation is by flame atomicabsorption spectrophotometry.10.14 Prepare the mixed metals standard solutions (see 9.8)and to each 100 mL, add 5 mL of CsCl solution, and 10 mL ofH3BO3solution (Note 5).10.15 See the appropriate ASTM test methods for subse
21、-quent quantitation.PROCEDURE BWET DIGESTION11. Scope11.1 This procedure is effective for the total digestion ofsuspended and bottom sediments for the subsequent determi-nation of aluminum, calcium, iron, magnesium, manganese,potassium, sodium, titanium, strontium, lithium, copper, zinc,cadmium, lea
22、d, cobalt, nickel, chromium, arsenic, antimony,and selenium.11.2 This practice may be appropriate for the subsequentdetermination of other metals provided the concentrations arehigh enough or if the instrumental sensitivity is sufficient.12. Interferences12.1 Numerous inter-element interferences, bo
23、th positiveand negative, exist for this procedure and have been docu-mented elsewhere.4, 5, 912.2 Interferences are eliminated, compensated for, or both,through the use of cesium chloride (CsCl), the use of mixedsalt standards, and background correction if quantitation is byatomic absorption spectro
24、scopy.13. Apparatus13.1 TFE-Fluorocarbon Beakers, 100-mL capacity, thickwall, capable of withstanding temperature up to 260C.13.2 Hot Plate, electric or gas, capable of reaching at least250C.9Walsh, J., “Interferences in the Determination of Titanium in Silicate Rocks andMinerals by Flame Atomic Abs
25、orption Spectrophotometry,” Analyst, Vol 102, 1977,pp. 972976.TABLE 1 Concentrations of Mixed MetalsSolutions 1, 2, and 3Standard 1,mg/LStandard 2,mg/LStandard 3,mg/LVolume (mL) 10 6 2Iron 100 60 20Magnesium 20 12 4Silicon 300 180 60Aluminum 150 90 30Titanium 20 12 4Calcium 50 30 10Sodium 25 15 5Pot
26、assium 35 21 7Manganese 4 2 1D4698 92 (2013)313.3 Perchloric Acid Hood, with appropriate washdownfacility and gas or electric outlets.14. Reagents14.1 Purity of ReagentsSee 9.1.14.2 Purity of Water See 9.2.14.3 The mixed salt standards are provided as a guide to theuser for use with atomic absorptio
27、n analyses to reduce matrixand interelement interferences. They have been found effectivefor the constituents listed in 11.1. They may have to bemodified to accommodate others.14.4 Standard Solution, Aluminum 1.00 mL = 1.00 mgAlDissolve 1.000 g of aluminum metal in 20 mL of HCl (spgr 1.19) with a tr
28、ace of a mercury salt to catalyze the reaction,and dilute to 1000 mL with water.14.5 Cesium Chloride Solution (CsCl) (4 g/L)See 9.4.14.6 Hydrochloric Acid (HCl), concentrated (sp gr 1.19).14.7 Hydrochloric Acid , (1+1)Add 250 mL concen-trated hydrochloric acid (sp gr 1.19) to 250 mL water. Store ina
29、 plastic bottle.14.8 Hydrochloric Acid , (1 + 49)Add 10 mL concen-trated hydrochloric acid (sp gr 1.19) to 490 mL water. Store ina plastic bottle.14.9 Hydrofluoric Acid (HF), concentrated (4851%) (sp gr1.19).14.10 Standard Solution, Iron, 1.00 mL = 1.00 mg FeDissolve 1.000 g iron metal in 20 mL HCl
30、(1 + 1) and dilute to1000 mL with water.14.11 Mixed Metals Solution, Stock (Minors)Dissolve byappropriate means, the following compounds or elements:cadmium metal (0.200 g), chromium metal (0.800 g), cobaltmetal (1.200 g), copper metal (0.800 g), lead metal (2.000 g),lithium carbonate (2.130 g), man
31、ganese metal (2.000 g), nickelmetal (1.200 g), stronium carbonate (1.685 g), and zinc metal(0.320 g), add 20 mL of HCl (sp gr 1.19), and dilute to 1000mL with water. This solution will contain the followingconcentrations: cadmium (200 mg/L), chromium (800 mg/L),cobalt (1200 mg/L), copper (800 mg/L),
32、 lead (2000 mg/L),lithium (400 mg/L), manganese (2000 mg/L), nickel (1200mg/L), strontium (1000 mg/L), and zinc (320 mg/L). Store ina plastic or TFE-fluorocarbon bottle.14.12 Mixed Metals Solution, Stock (Majors)Dissolve byappropriate means, the following compounds or elements:aluminum metal (1.500
33、g), calcium carbonate (1.249 g), ironmetal (1.000 g), magnesium metal (0.200 g), manganese metal(0.040 g), potassium chloride (0.668 g), sodium chloride(0.636 g), and ammonium titanyl oxalate (1.227 g).Add 20 mLHCl (sp gr 1.19), and dilute to 1000 mL with water. Thissolution will contain the followi
34、ng concentrations: aluminum(1500 mg/L), calcium (500 mg/L), iron (1000 mg/L), magne-sium (200 mg/L), manganese (40 mg/L), potassium (350mg/L), sodium (250 mg/L), and titanium (200 mg/L). Store ina plastic or TFE-fluorocarbon bottle.14.13 Mixed Metals Solution, Standard (Minors)Take 100mL of mixed me
35、tals stock solution (minors) (14.11), add 20mL HCl (sp gr 1.19), and dilute to 1000 mL in volumetricglassware with water. This solution will contain the followingconcentrations: cadmium (20 mg/L), chromium (80 mg/L),cobalt (120 mg/L), copper (80 mg/L), lead (200 mg/L), lithium(40 mg/L), manganese (2
36、00 mg/L), nickel (120 mg/L), stron-tium (100 mg/L), and zinc (32 mg/L). Store in a plastic orTFE-fluorocarbon bottle. Solution is stable for 3 months.14.14 Mixed Metals Solutions, Standards 1, 2, and 3Takerespectively, a 10-, 5-, and 1-mL aliquots of mixed metalsstandard solution (14.13), and add to
37、 each 4 mL HCl (sp gr1.19), 20 mL of mixed metals standard stock solution (14.12).Dilute to 200 mL in volumetric glassware with water. Concen-trations are given in Table 2. Store in plastic or TFE-fluorocarbon bottles. Prepare fresh for each analysis.14.15 Mixed Metals Solutions, Standards 4, 5, and
38、 6Takerespectively, a 10-, 6-, and 2-mLaliquots of mixed metals stocksolution (14.12), and add 2 mL HCl (sp gr 1.19), and 10 mL ofthe CsCl solution 14.5). Dilute to 100 mL in volumetricglassware with water. Concentrations are given in Table 2.14.16 Mixed Metals Solutions, Standards 7, 8, and 9Takea
39、10-mL aliquot of standard solutions 4, 5, and 6 (14.5), add 2mL HCl (sp gr 1.19), and add 10 mL of the CsCl solution(14.5). Dilute to 100 mL in volumetric glassware with water.Concentrations are given in Table 3. Store in plastic orTFE-fluorocarbon bottles. Prepare fresh for each analysis.14.17 Nitr
40、ic Acid (HNO3), concentrated (sp gr 1.41).14.18 Perchloric Acid (HClO4), concentrated (70 to 72%)(sp gr 1.67).14.19 Standard Solution, Sodium 1.00 mL = 1.00 mg NaDissolve 2.542 g NaCl, in water, add 20 mL HCl (sp gr 1.19),and dilute to 1000 mL with water.14.20 Standard Solution, Titanium 1.00 mL = 1
41、.00 mgTiDissolve 6.135 g ammonium titanyl oxalate in water, anddilute to 1000 mL with water.14.21 Working Solution, Titanium Take respectively, a20-, 10-, and 5-mL aliquot of the titanium standard solution(14.20), and add 100 mL of the aluminum standard solution(14.4), 50 mL of the iron standard sol
42、ution (14.10), 35 mL ofthe sodium standard solution (14.19), 200 mL of the CsClsolution (14.5), and 20 mL HCl (sp gr 1.19). Dilute to 1000 mLin volumetric glassware with water. The standards contain,respectively, 20, 10, and 5 mg/L titanium.15. Procedure15.1 See 10.1 to 10.4.TABLE 2 Concentrations o
43、f Mixed MetalsSolutions 4, 5, and 6Standard 4,mg/LStandard 5,mg/LStandard 6,mg/LVolume (mL) 10 6 2Aluminum 150 90 30Iron 100 60 20Magnesium 20 12 4Manganese 4 2 1D4698 92 (2013)415.2 Weigh and transfer 0.5000 g of finely ground sample toa 100 mL TFE-fluorocarbon beaker; weigh out appropriaterock or
44、sediment standards as well.NOTE 6This practice can be used with sample weights of between0.2500 to 1.000 g, with appropriate adjustments to the final solutionvolumes and acid strengths (15.2 and 15.9). Larger weights (greater than1.000 g) may be used, but will require an extra digestion with HF andH
45、ClO4(see 15.6 and 15.7).15.3 Carry several blanks through the procedure by usingempty beakers.15.4 Place the hot plate in a perchloric acid hood, and turnon the hood and hotplate. Adjust the hot plate to produce asurface temperature of 200C.15.5 To each beaker, add 6 mL HNO3(sp gr 1.41), andplace it
46、 on the hot plate for approximately 30 min.NOTE 7Warning: This step is designed to oxidize organic matter inthe sample. It is imperative that this step be carried out prior to theaddition of perchloric acid, otherwise a violent explosion could occur.Resistant organics, such as coals, may require a s
47、econd treatment withnitric acid.15.6 Remove the beakers from the hot plate and wait 5 min.Add 6 mL of HF (sp gr 1.19), 2 ml of HClO4(sp gr 1.67), andreturn the beakers to the hot plate. Continue heating thebeakers until the evolution of white perchloric fumes and thesolution has reached incipient dr
48、yness; however, do not bakethe solutions.15.7 Repeat 15.6.15.8 Remove the beakers from the hot plate and wait 5 min.Add 2 mL of HClO4(sp gr 1.67), and return the beakers to thehot plate. Continue heating until the solution has reachedincipient dryness; however, do not bake the solutions.15.9 Remove
49、the beakers from the hot plate, and lower thetemperature to 100C. Add 2 mL of HCl (1 + 1) and swirl thebeaker; add 10 mL of water and return to the hot plate todissolve the residue.NOTE 8If quantitation is to be by graphite furnace atomic absorptionspectrophotometry, substitute 2 mL of HNO3(1 + 1) for HCl (1 + 1). Ifquantitation is to be by hydride generation (for example, arsenic,antimony, or selenium), then substitute 25 mL of HCl (sp gr 1.19).15.10 Cool the beakers, and pour each solution into a 50-mLvolumetric flask. Rinse the beaker seve
