CD-ROM 3050B - 1Revision 2
December 1996
METHOD 3050B ACID DIGESTION OF SEDIMENTS, SLUDGES, AND SOILS
1.0 SCOPE AND APPLICATION
1.1 This method has been written to provide two parate digestion procedures, one for
the preparation of diments, sludges, and soil samples for analysis by flame atomic absorption spectrometry (FLAA) or inductively coupled plasma atomic emission spectrometry (ICP-AES) and one for the preparation of diments, sludges, and soil samples for analysis of samples by Graphite Furnace AA (GFAA) or inductively coupled plasma mass spectrometry (ICP-MS). The extracts from the two procedures are not interchangeable and should only be ud with the analytical determinations outlined in this ction. Samples prepared by this method may be analyzed by ICP-AES or GFAA for all the listed metals as long as the detecion limits are adequate for the required end-u of the data. Alternative determinative techniques may be ud if they are scientifically valid and the QC criteria of the method, including tho dealing with interferences, can be achieved.Other eleme
nts and matrices may be analyzed by this method if performance is demonstrated for the analytes of interest, in the matrices of interest, at the concentration levels of interest (See Section 8.0). The recommended determinative techniques for each element are listed below: FLAA/ICP-AES GFAA/ICP-MS Aluminum
Magnesium Arnic Antimony
Mangane Beryllium Barium
Molybdenum Cadmium Beryllium
Nickel Chromium Cadmium
Potassium Cobalt Calcium
Silver Iron Chromium
Sodium Lead Cobalt
Thallium Molybdenum Copper
Vanadium Selenium Iron就字草书
Zinc Thallium
企盼的近义词Lead
Vanadium 1.2This method is not a total digestion technique for most samples. It is a very strong
acid digestion that will dissolve almost all elements that could become “environmentally available.”By design, elements bound in silicate structures are not normally dissolved by this procedure as they are not usually mobile in the environment. If absolute total digestion is required u Method 3052.2.0 SUMMARY OF METHOD
放松的反义词2.1For the digestion of samples, a reprentative 1-2 gram (wet weight) or 1 gram (dry
weight) sample is digested with repeated additions of nitric acid (HNO ) and hydrogen peroxide 3(H O ).
22 2.2For GFAA or ICP-MS analysis, the resultant digestate is reduced in volume while
heating and then diluted to a final volume of 100 mL.
2.3For ICP-AES or FLAA analys, hydrochloric acid (HCl) is added to the initial
digestate and the sample is refluxed. In an optional step to increa the solubility of some metals (e Section 7.3.1: NOTE), this digestate is filtered and the filter paper and residues are rind, first
with hot HCl and then hot reagent water. Filter paper and residue are returned to the digestion flask, refluxed with additional HCl and then filtered again. The digestate is then diluted to a final volume of 100 mL.
2.4If required, a parate sample aliquot shall be dried for a total percent solids determination.
3.0 INTERFERENCES
3.1 Sludge samples can contain diver matrix types, each of which may prent its own analytical challenge. Spiked samples and any relevant standard reference material should be procesd in accordance with the quality control requirements given in Sec. 8.0 to aid in determining whether Method 3050B is applicable to a given waste.
4.0 APPARATUS AND MATERIALS
4.1 Digestion Vesls - 250-mL.
4.2 Vapor recovery device (e.g., ribbed watch glass, appropriate refluxing device, appropriate solvent handling system).
4.3 Drying ovens - able to maintain 30E C + 4E C.
4.4 Temperature measurement device capable of measuring to at least 125E C with suitable precision and accuracy (e.g., thermometer, IR nsor, thermocouple, thermister, etc.)
4.5 Filter paper - Whatman No. 41 or equivalent.
4.6 Centrifuge and centrifuge tubes.
4.7Analytical balance - capable of accurate weighings to 0.01 g.
4.8Heating source - Adjustable and able to maintain a temperature of 90-95E C. (e.g., hot plate, block digestor, microwave, etc.)
4.9Funnel or equivalent.
4.10Graduated cylinder or equivalent volume measuring device.
4.11Volumetric Flasks - 100-mL.
5.0 REAGENTS
5.1 Reagent grade chemicals shall be ud in all tests. Unless otherwi indicated, it is intended that all reagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society, where such specifications are available. Other grades may be ud, provided it is first ascertained that the reagent is of sufficiently high purity to permit its u without lesning the accuracy of the determination. If the purity of a reagent is questionable, analyze the reagent to determine the level of impurities. The reagent blank must be less than the MDL in order to be ud.
CD-ROM3050B - 2Revision 2
December 1996
CD-ROM 3050B - 3Revision 2
December 1996
5.2Reagent Water. Reagent water will be interference free. All references to water in
the method refer to reagent water unless otherwi specified. Refer to Chapter One for a definition of reagent water.
5.3 Nitric acid (concentrated), HNO . Acid should be analyzed to determine level of
3impurities. If method blank is < MDL, the acid can be ud.
5.4 Hydrochloric acid (concentrated), HCl. Acid should be analyzed to determine level
of impurities. If method blank is < MDL, the acid can be ud.
5.5 Hydrogen peroxide (30%), H O . Oxidant should be analyzed to determine level of
22impurities. If method blank is < MDL, the peroxide can be ud.
6.0 SAMPLE COLLECTION, PRESERVATION, AND HANDLING
6.1 All samples must have been collected using a sampling plan that address the
considerations discusd in Chapter Nine of this manual.
6.2 All sample containers must be demonstrated to be free of contamination at or below
the reporting limit. Plastic and glass containers are both suitable. See Chapter Three, Section 3.1.3,for further information.
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6.3
Nonaqueous samples should be refrigerated upon receipt and analyzed as soon as
possible.6.4It can be difficult to obtain a reprentative sample with wet or damp materials. Wet
samples may be dried, crushed, and ground to reduce subsample variability as long as drying does not affect the extraction of the analytes of interest in the sample.
7.0 PROCEDURE
7.1 Mix the sample thoroughly to achieve homogeneity and sieve, if appropriate and
necessary, using a USS #10 sieve. All equipment ud for homogenization should be cleaned according to the guidance in Sec. 6.0 to minimize the potential of cross-contamination. For each digestion procedure, weigh to the nearest 0.01 g and transfer a 1-2 g sample (wet weight) or 1 g sample (dry weight) to a digestion vesl. For samples with high liquid content, a larger sample size
may be ud as long as digestion is completed.NOTE: All steps requiring the u of acids should be conducted under a fume hood by
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properly trained personnel using appropriate laboratory safety equipment. The u of an acid
vapor scrubber system for waste minimization is encouraged.
7.2 For the digestion of samples for analysis by GFAA or ICP-MS, add 10 mL of 1:1
HNO , mix the slurry, and cover with a watch glass or vapor recovery device. Heat the sample to 395E C ± 5E C and reflux for 10 to 15 minutes without boiling. Allow the sample to cool, add 5 mL of concentrated HNO , replace the cover, and reflux for 30 minutes. If brown fumes are generated,3indicating oxidation of the sample by HNO , repeat this step (addition of 5 mL of conc. HNO ) over 3 3and over until no brown fumes are given off by the sample indicating the complete reaction with HNO . Using a ribbed watch glass or vapor recovery system, either allow the solution to evaporate 3to approximately 5 mL without boiling or heat at 95E C ± 5E C without boiling for two hours. Maintain a covering of solution over the bottom of the vesl at all times.
CD-ROM 3050B - 4Revision 2
December 1996samples for analysis by GFAA or ICP-MS by adding 10 mL of 1:1 HNO , mixing the slurry and
3then covering with a vapor recovery device. Heat the sample to 95E C ± 5E C and reflux for
5 minutes at 95E C ± 5E C without boiling. Allow the sample to cool for 5 minutes, add 5 mL
of concentrated HNO , heat the sample to 95E C ± 5E C and reflux for 5 minutes at 95E C ±
35E C. If brown fumes are generated, indicating oxidation of the sample by HNO , repeat this
3step (addition of 5 mL concentrated HNO ) until no brown fumes are given off by the sample
3indicating the complete reaction with HNO . Using a vapor recovery system, heat the sampleaoo
3to 95E C ± 5E C and reflux for 10 minutes at 95E C ± 5E C without boiling.
7.2.1 After the step in Section 7.2 has been completed and the sample has cooled,
add 2 mL of water and 3 mL of 30% H O . Cover the vesl with a watch glass or vapor
22recovery device and return the covered vesl to the heat source for warming and to start
the peroxide reaction. Care must be taken to ensure that loss do not occur due to凉菜100款图片
excessively vigorous effervescence. Heat until effervescence subsides and cool the vesl.
NOTE: Alternatively, for direct energy coupled devices: After the Sec. 7.2 “NOTE”
step has been completed and the sample has cooled for 5 minutes, add slowly 10 mL
of 30% H O . Care must be taken to ensure that loss do not occur due to
22excessive vigorous effervence. Go to Section 7.2.3.
7.2.2 Continue to add 30% H O in 1-mL aliquots with warming until the
22effervescence is minimal or until the general sample appearance is unchanged.NOTE: Do not add more than a total of 10 mL 30% H O .
22 7.2.3 Cover the sample with a ribbed watch glass or vapor recovery device and
continue heating the acid-peroxide digestate until the volume has been reduced to
approximately 5 mL or heat at 95E C ± 5E C without boiling for two hours. Maintain a covering
of solution over the bottom of the vesl at all times. NOTE: Alternatively, for direct energy coupled devices: Heat the acid-peroxide
digestate to 95E C ± 5E C in 6 minutes and remain at 95E C ± 5E C without boiling for
10 minutes.
7.2.4After cooling, dilute to 100 mL with water. Particulates in the digestate should
then be removed by filtration, by centrifugation, or by allowing the sample to ttle. The
sample is now ready for analysis by GFAA or ICP-MS.
7.2.4.1
Filtration - Filter through Whatman No. 41 filter paper (or
equivalent). 7.2.4.2 Centrifugation - Centrifugation at 2,000-3,000 rpm for
10 minutes is usually sufficient to clear the supernatant.
7.2.4.3 The diluted digestate solution contains approximately 5% (v/v)
HNO . For analysis, withdraw aliquots of appropriate volume and add any required
3reagent or matrix modifier.
7.3For the analysis of samples for FLAA or ICP-AES, add 10 mL conc. HCl to the sample
digest from 7.2.3 and cover with a watch glass or vapor recovery device. Place the sample on/in the heating source and reflux at 95C ± 5E C for 15 minutes.
o
CD-ROM 3050B - 5Revision 2
December 1996samples for analysis by FLAA and ICP-AES by adding 5 mL HCl and 10 mL H O to the 2sample digest from 7.2.3 and heat the sample to 95C ± 5
E C, Reflux at 95C ± 5E C without o o boiling for 5 minutes.
7.4Filter the digestate through Whatman No. 41 filter paper (or equivalent) and collect
filtrate in a 100-mL volumetric flask. Make to volume and analyze by FLAA or ICP-AES.NOTE: Secti
on 7.5 may be ud to improve the solubilities and recoveries of antimony,barium, lead, and silver when necessary. The steps are optional and are not required on a routine basis.
7.5Add 2.5 mL conc. HNO and 10 mL conc. HCl to a 1-2 g sample (wet weight) or 1 g
3sample (dry weight) and cover with a watchglass or vapor recovery device. Place the sample on/in the heating source and reflux for 15 minutes.
7.5.1Filter the digestate through Whatman No. 41 filter paper (or equivalent) and
collect filtrate in a 100-mL volumetric flask. Wash the filter paper, while still in the funnel,
with no more than 5 mL of hot (~95E C) HCl, then with 20 mL of hot (~95E C) reagent water.
Collect washings in the same 100-mL volumetric flask.
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7.5.2Remove the filter and residue from the funnel, and place them back in the
vesl. Add 5 mL of conc. HCl, place the vesl back on the heating source, and heat at
95E C ± 5E C until the filter paper dissolves. Remove the vesl from the heating source and
wash the cover and sides with reagent water. Filter the residue and collect the filtrate in the
same 100-mL volumetric flask. Allow filtrate to cool, then dilute to volume.NOTE: High concentrations of metal salts with temperature-nsitive solubilities can
result in the formation of precipitates upon cooling of primary and/or condary filtrates. If precipitation occurs in the flask upon cooling, do not dilute to volume.
7.5.3If a precipitate forms on the bottom of a flask, add up to 10 mL of
concentrated HCl to dissolve the precipitate. After precipitate is dissolved, dilute to volume
with reagent water. Analyze by FLAA or ICP-AES.
7.6
Calculations
7.6.1 The concentrations determined are to be reported on the basis of the actual
weight of the sample. If a dry weight analysis is desired, then the percent solids of the
sample must also be provided.
7.6.2 If percent solids is desired, a parate determination of percent solids must
be performed on a homogeneous aliquot of the sample.
8.0 QUALITY CONTROL
8.1All quality control measures described in Chapter One should be followed.8.2 For each batch of samples procesd, a method blank should be carried throughout
the entire sample preparation and analytical process according to the frequency described in Chapter One. The blanks will be uful in determining if samples are being contaminated. Refer to Chapter One for the proper protocol when analyzing method blanks.
