ASTM E1726-21

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it 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 version
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Designation: E1726 − 20 E1726 − 21
Standard Practice for
Preparation of Soil Samples by Hotplate Digestion for
Subsequent Lead Analysis
This standard is issued under the fixed designation E1726; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This practice covers drying, homogenization, and acid digestion of soil samples and associated quality control (QC) samples
using a hot plate type method for the determination of lead using laboratory atomic spectrometry analysis techniques such as
inductively coupled plasma atomic emission spectrometry (ICP-AES), flame atomic absorption spectrometry (FAAS), and graphite
furnace atomic absorption spectrometry (GFAAS).
1.2 This practice is based on U.S. EPA SW 846, Test Method 3050.
1.3 This practice contains notes that are explanatory and are not part of the mandatory requirements of this standard.
1.4 The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided for
information only and are not considered standard.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.6 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
D1129 Terminology Relating to Water
D1193 Specification for Reagent Water
D1356 Terminology Relating to Sampling and Analysis of Atmospheres
E288 Specification for Laboratory Glass Volumetric Flasks
E1605 Terminology Relating to Lead in Buildings
2.2 U.S. Government Analytical Method:
U.S. EPA SW 846 Test Methods for Evaluating Solid Waste Physical/Chemical Methods
This practice is under the jurisdiction of ASTM Committee D22 on Air Quality and is the direct responsibility of Subcommittee D22.12 on Sampling and Analysis of
Lead for Exposure and Risk Assessment.
Current edition approved Sept. 1, 2020Sept. 1, 2021. Published September 2020October 2021. Originally approved in 1995. Last previous edition approved in 20162020
as E1726 – 16.E1726 – 20. DOI: 10.1520/E1726-20.10.1520/E1726-21.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Available from U.S. Government Publishing Office, 732 N. Capitol St., NW, Washington, DC 20401-0001, http://www.gpo.gov.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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2.3 ISO Standards:
ISO Guide 30 Terms and Definitions Used in Connection with Reference Materials
ISO 1042 Laboratory glassware — One-mark volumetric flasks
ISO 8655 Piston-operated volumetric apparatus — Part 1: Terminology, general requirements and user recommendations
3. Terminology
3.1 Definitions—For definitions of terms relating to the preparation of dried paint samples that are not given here, refer to
Terminologies D1129, D1356, or E1605.
3.1.1 batch, n—a group of field or quality control samples that are processed together using the same reagents and equipment.
3.1.2 digestate, n—the acidified aqueous solution that results from digestion of the sample.
3.1.3 digestion, n—high temperature sample preparation process that involves chemical breakdown to solubilize targeted analytes
present in a sample, to result in an acidified aqueous solution called the digestate.
3.1.4 method blank, n—a sample, devoid of analyte, that is analyzyed to determine its contribution to the total blank (background)
reading.
3.1.5 non-spiked sample, n—a sample, devoid of analyte, that is targeted for addition of analyte but is not fortified with all target
analytes prior to sample preparation.
3.1.5.1 Discussion—
Analysis results for this sample are used to correct for background levels in the blank medium that is used for spiked and spiked
duplicate samples.
3.1.6 reagent blank, n—a digestate that reflects the maximum treatment given any one sample within a batch of samples, except
that it has no sample placed initially into the digestion vessel. (The same reagents and processing conditions that are applied to
field samples within a batch are also applied to the reagent blank.)
3.1.6.1 Discussion—
Analysis results from this sample provide information on the level of potential contamination resulting from only laboratory
sources that are experienced by samples processed within the batch.
3.1.7 reference material (certified reference material) (CRM), n—reference material accompanied by a certificate, one or more of
whose property values are certified by a procedure which establishes its traceability to an accurate realization of the unit in which
the property values are expressed; each certified value is accomplished by an uncertainty at a stated level of confidence
(ISO Guide 30).
3.1.8 spiked sample or spiked duplicate sample, n—a blank medium that contains no purposely added analyte to which a known
amount of analyte is added before preparation.
3.1.8.1 Discussion—
Analysis results for these samples are used to provide information on the precision and accuracy of the overall process.
4. Summary of Practice
4.1 A representative soil sample is dried and homogenized, and then digested (in a batch mode with other samples) on a hot plate
using nitric acid and hydrogen peroxide. The digestate is diluted for final volume prior to lead measurement.
5. Significance and Use
5.1 There is a need to monitor the lead content in and around buildings and related structures in order to determine the potential
lead hazard. Hence, effective and efficient methods are required for the preparation of soil samples for determination of their lead
content.
5.2 This practice may be used for the digestion of soil samples that are collected during various construction and renovation
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.
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activities associated with lead abatement in and around buildings and related structures. The practice is also suitable for the
digestion of soil samples for lead analyses collected from other locations, such as near roads and steel structures.
5.3 This practice is intended to be used to prepare samples that have been collected for hazard assessment purposes.
5.4 This practice is not capable of determining lead bound within matrices, such as silica, that are not soluble in nitric acid.
5.5 This practice includes drying and homogenization steps in order to help assure that reported lead results are representative of
the sample and are independent of potential differences in soil moisture levels among different sampling locations or changing
weather conditions.
6. Apparatus
6.1 Equipment:
6.1.1 Analytical Balance, capable of accurately determining the mass to the nearest 0.001 g.
6.1.2 Drying Oven, capable of maintaining a temperature of 100°C to 120°C.
6.1.3 Electric Hot Plate, capable of maintaining a temperature of 80°C to 100°C as measured with a thermometer placed into a
beaker or flask filled with water sitting on the hot plate head. When required to reduce the presence of hot spots in the electrical
hot plate, place a 2 cm to 2.5 cm (0.75 in to 1 in.) thick aluminum plate on the burner head.
6.1.4 Grinding Apparatus—Mortar and pestle (porcelain or agate), shatter box, or mixer mill.
6.1.5 Micropipettors with Disposable Plastic Tips conforming to ISO 8655, sizes needed to make reagent additions, and spiking
standards (see Note 1).
NOTE 1—In general, the following sizes should be readily available: 1 mL to 5 mL adjustable, 1000 μL, 500 μL, 250 μL, and 100 μL.
6.1.6 Sieves, 4.75 mm (U.S. Standard No. 4), 2 mm (No. 10), and 500 μm (No. 35), plastic or stainless steel (see Note 2). When
sieves containing soldered joints are used, then all solder joints shall be coated with epoxy resin prior to use to protect samples
from potential lead contamination originating in the solder. Visually inspect prior to use for the presence of bare metal.
NOTE 2—Plastic or stainless steel sieves are better for use instead of brass sieves to alleviate possible lead contamination of the soil samples from contact
with lead solder common to brass sieves.
6.1.7 Thermometers, red alcohol, that cover a range from 0°C to 110°C
6.2 Glassware and Supplies:
6.2.1 Borosilicate Glassware—Volumetric flasks with stoppers meeting Specification E288 or conforming to ISO 1042, 100 mL;
Griffin beakers, 100 mL, 150 mL or 250 mL; watch glasses sized to cover Griffin beakers.
6.2.2 Plastic Gloves, powderless.
6.2.3 Air-Tight Sample Containers—1 L (1 qt) or 4 L (1 gal) re-sealable plastic bags, or plastic 50 mL centrifuge tubes.
6.2.4 Volumetric Flasks—meeting Specification E288 or conforming to ISO 1042, 100 mL and other sizes as needed to make
dilutions of sample digests or lead standards used for fortification of spiked samples.
6.2.5 Tongs, metal.
6.2.6 Spoon, stainless steel.
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7. Reagents
7.1 Purity of Reagents—Reagent grade chemicals shall be used in this practice. Unless otherwise indicated, all reagents shall
conform to the specifications for the Committee on Analytical Reagents of the American Chemical Society, where such
specifications are available. Other grades shall not be used unless it is first ascertained that the reagent is of sufficiently high purity
to permit its use without lessening accuracy of the determination.
7.2 Nitric Acid—Concentrated, suitable for atomic spectrometry analysis, such as spectroscopic grade.
7.3 Hydrogen Peroxide, mass fraction 30 %, suitable for atomic spectrometry analysis such as spectroscopic grade.
7.4 Acetone, reagent, spectroscopic grade.
7.5 Water—Unless otherwise indicated, references to water shall mean reagent water as defined by Type I of Specification D1193.
(ASTM Type I water: minimum resistivity of 16.7 megohm·cm, or equivalent.)
7.6 Calibration Stock Solution, 100 μg/mL of lead (Pb) CRM in dilute (typically 2 %) nitric acid.
8. Equipment Preparation
8.1 Wash glassware and plastic equipment with laboratory detergent, rinse with tap water, soak for at least 4 hours in volume
fraction 35 % nitric acid and water, rinse three times with ASTM Type I Water, and allow to dry preferably in a fume hood.
Commercial, automatic systems are available that perform a similar process.
8.2 Alternatively, soak glassware and plastic equipment in volume/volume 1+1 nitric acid and water in a plastic tub preferably
in a working hood with the hood sash down, rinse three times with ASTM Type I Water, and allow to dry preferably in a fume
hood.
9. Sample Preparation Procedure
9.1 Sample Pre-Treatment:
9.1.1 Treat each sample in a processing batch equally.
9.1.2 If possible before removal, break up the soil
6,7,8,9
sample within the original containers containing the samples (see Note 3).
NOTE 3—This will not be possible for wet soil samples.
9.1.3 Label an acid-cleaned 100 mL, 150 mL, or 250 mL Griffin beaker (or other vessel suitable for oven drying of soils that will
not contaminate the sample with lead) with a high temperature wax pen or any other marker that will be visible after exposure to
the drying oven.
9.1.4 Transfer the entire soil sample to the labeled Griffin beaker. Cover with a watch glass (tip to one side to permit moisture
removal), and place in a drying oven for a minimum of 6 h at a temperature of 110°C 6 10°C. Samples that cake or plug the sieve
require additional drying (see Note 4).
ACS Reagent Chemicals, Specifications and Procedures for Reagents and Standard-Grade Reference Materials, American Chemical Society, Washington, DC. For
suggestions on the testing of reagents not listed by the American Chemical Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset, U.K., and
the United States Pharmacopeia and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.
U.S. Environmental Protection Agency, Soil Sampling Quality Assurance User’s Guide, Second Edition, EPA/600/8-69/046, March 1989, available from
http://www.epa.gov.
Rohlf, F., Akcakaya, H., and Ferraro, S., “Optimizing Composite Sampling Protocols,” Environmental Science and Technology, Vol 30, 1996, pp. 2899–2905.
Australia National Environmental Health Forum Monograph, Soil Series No. 3, Composite Sampling, 1996, available from http://www.enhealth.nphp.gov.au.
U.S. Environmental Protection Agency, Guidance for Obtaining Representative Laboratory Analytical Subsamples from Particulate Laboratory Samples, EPA/600/R-
03/027, November 2003, available from http://www.epa.gov.
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NOTE 4—Soil samples should not cake or exhibit packing characteristic of moisture, but should flow freely through the sieve (see 8.1.79.1.7) when broken
apart.
9.1.5 If the received soil sample is excessively large, then any attempts to sub-sample prior to drying and sieving are likely to
cause bias. If
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