A747/R-92-006
&EPA
United States
Environmental Protection
Agency
Prevention, Pesticides,
and Toxic Substances
(TS-798)
EPA 747-R-92-006
May 1993
Pb-Based Paint
Laboratory Operations
Guidelines: Analysis of
Pb in Paint, Dust,
and Soil
Revision 1.0
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Pb-Based Paint
Laboratory Operations Guidelines:
Analysis of Pb in Paint, Dust, and Soil
Revision 1.0
Technical Programs Branch
:x Office of Pollution Prevention and Toxics
iX U. S. Environmental Protection Agency
J 401 M Street, S.W.
l Washington, D.C. 20460
John V. Scalera, Work Assignment Manager
Janet C. Remmers, Project Officer
May 14,1993
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DISCLAIMER
This document has been reviewed and approved for publication by the
Office of Prevention, Pesticides, and Toxic Substances, U.S. Environ-
mental Protection Agency. The use of trade names or commercial
products does not constitute Agency endorsement or recommendation
for use.
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NOTICE
This guide is limited to the analysis of Pb in paint film or chips, Pb-based
paint contaminated soils, and deposited dust (vacuum dust and wipe
samples). There are many programs covering Pb in other matrices, such
as air (occupational and environmental), drinking water, eating utensils,
solid waste, hazardous waste, gasoline, and blood. Separate regulatory
guidance is already in place for Pb in these matrices. This guide
provides needed information for laboratory chemists and managers in
laboratories that seek accreditation for Pb in paint, soil, and deposited
dust matrices. The guideline also provides recommendations for good
laboratory practices for these laboratories.
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AUTHORS AND CONTRIBUTORS
Midwest Research Institute (MRI) was requested by the Environmental
Protection Agency (EPA) to develop a good laboratory practices guideline for
laboratory chemists. This Laboratory Operations Guideline provides guidance to
laboratories seeking accreditation by organizations participating in the EPA National
Lead Laboratory Accreditation Program (NLLAP). The NLLAP recognizes laboratories
which demonstrate, through proficiency testing and systems audits, the capability to
analyze for Pb in paint, soil, and deposited dust, including vacuumed dust and wipe
samples.* The guideline was developed with the cooperation of the Technical
Programs Branch, Office of Pollution Prevention and Toxics (OPPT) under EPA
Contract 68-DO-0137. A working meeting to gather information for the basis of this
report was held in Gaithersburg, Maryland, from June 24 to 26, 1992, with a group of
metals laboratory experts. The affiliations of the working group and the role of each
organization are presented below.
MIDWEST RESEARCH INSTITUTE (MRI)
MRI was responsible for the planning and the conduct of the working meeting.
Dr. Larry Lowry, the Work Assignment Leader, had primary responsibility for conduct-
ing the meeting and writing the final reports with input from working group members
and Mr. Paul Constant, Dr. Gary Dewalt, and Mr. Jack Balsinger from MRI.
* In order to avoid confusion in the terms lead (for Pb) and lead (for leader), the
following conventions are used. Pb will be used for the heavy metal. Lead will be
used for all other uses. The term, good laboratory practices, will not be used here
since it refers to the EPA/TSCA GLP standards. The preferred term is Laboratory
Operations Guidelines (LOG). The term, paint, in this document refers to dried paint
film or paint chips and not to liquid, uncured paint.
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WORKING GROUP PARTICIPANTS
The following individuals actively participated in the working meeting and in the
review of this document. Their affiliations and the organizations they represent are
listed.
• Joseph J. Breen, Ph.D.
Chief, Industrial Chemistry Branch
Economics, Exposure and Technology Division
Office of Pollution Prevention and Toxics
U.S. Environmental Protection Agency
401 M Street, SW
Washington, DC 20460
• Michael S. Epstein, Ph.D.
National Institute of Standards and Technology
B-220 Chemistry Building
Gaithersburg, MD 20899
Research chemist in the Inorganic Analytical Research Division of the
Chemical Science and Technology Laboratory. Currently responsible for
Atomic Absorption (AA) and DC Plasma Emission Spectrometry, he has 15
years of experience in AA and plasma emission, including the analysis of Pb
paint film materials. He helped to coordinate the certification of SRMs for soils
and sediments.
• Mr. Lee Friell, M.S.
Manager, Iowa Hygienic Laboratory
Henry A. Wallace Building
Des Moines, IA 50319
Represents the Association of State and Territorial Public Health Laboratory
Directors (ASTPHLD) and state laboratory accrediting bodies. An inorganic
chemist with experience in Inductively Coupled Plasma Emission Spectrometry
(ICP-AES) EPA work on soil and water. His laboratory is a CLP-certified
laboratory that conducts Pb analyses in many different matrices.
• Mr. Fred Grunder
Manager, Laboratory Accreditation Program
American Industrial Hygiene Association
2700 Prosperity Avenue, Suite 250
Fairfax, VA 22031
Site assessor and member of the American Industrial Hygiene Association
(AIHA) Environmental Lead Laboratory Accreditation Committee (ELLAC).
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• Larry K. Lowry, Ph.D.
Senior Advisor, Exposure Assessment
Midwest Research Institute
425 Volker Blvd.
Kansas City, MO 64110
Work Assignment Leader (WAL) and principal author of the report.
• Mr. John V. Scalera
Technical Programs Branch,
Chemical Management Division,
Office of Pollution Prevention and Toxics
U.S. Environmental Protection Agency
401 M Street, SW
Washington, DC 20460
Work Assignment Manager (WAM) and principal EPA reviewer.
• James Scott, M.S.
Georgia Power Company
Environmental Laboratory
5131 Maner Road
Smyrna, GA 30080
A lead assessor for the American Association for Laboratory Accreditation
(A2LA).
• Barbara J. Weaver, C.I.H.
Lancaster Laboratories, Inc.
2425 New Holland Pike
Lancaster, PA 17601
Represents the laboratory director, Dr. Wilson Hershey, the American Council
of Independent Laboratories (ACIL) and the Committee on National
Accreditation of Environmental Laboratories (CNAEL).
EPA CHEMICAL MANAGEMENT DIVISION, TECHNICAL PROGRAMS BRANCH
(CMD/TPB)
EPA was responsible for oversight in the development of the study plan;
managing and coordinating the conduct of the overall project; and reviewing, editing,
and finalizing this report. Key staff included Mr. John V. Scalera, Work Assignment
Manager; Janet C. Remmers, Project Officer; and Dr. Joseph J. Breen, former Project
Officer.
VII
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EXTERNAL REVIEWERS
The following individuals served as external reviewers of this document. Their
participation in this review is gratefully acknowledged.
Kevin Ashley, Ph.D., NIOSH, Cincinnati, OH.
Daniel Paschal, Ph.D., CDC, Atlanta, GA.
Barbara J. Weaver, C.I.H., Lancaster Laboratories, Lancaster, PA.
Michael S. Epstein, Ph.D., NIST, Gaithersburg, MD.
May 14, 1993
VIII
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CONTENTS
Authors and Contributors v
Executive Summary xi
1.0 Introduction 1
1.1 Background 1
1.2 EPA recognition of laboratories 1
1.3 Other programs 2
1.4 Purpose 2
1.5 Approach 2
2.0 Facilities and Personnel Qualifications 5
2.1 Facilities 5
2.2 Personnel and qualifications 6
3.0 Quality Assurance 9
3.1 The quality system 9
3.2 Review of the quality system 11
3.3 Quality control 11
3.4 Quality control practices 13
4.0 Required Standard Operating Procedures (SOPs) 17
4.1 Overview 17
4.2 Elements of SOPs 17
5.0 Field Sampling 19
5.1 Overview 19
5.2 Minimum sample size 19
5.3 Wipe sampling 21
5.4 Paint chips 22
5.5 Dust—vacuumed samples 22
5.6 Soil samples 22
5.7 Blanks and background samples 22
5.8 Duplicate field samples 23
6.0 Laboratory Sampling 25
6.1 Solids—general considerations 25
6.2 Wipe samples 26
6.3 Paint chips 26
6.4 Dust—vacuumed samples 27
6.5 Soils 27
6.6 Sample tracking and storage 27
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7.0 Sample Digestion Procedures 29
8.0 Instrumentation 31
8.1 Atomic Absorption Spectrometry using direct
flame aspiration 31
8.2 Atomic Absorption Spectrometry using the
graphite furnace 32
8.3 Inductively Coupled Plasma Emission Spectrometry ... 33
8.4 Other instrumentation 34
9.0 Analytical Methods and Calibration 35
9.1 List of methods 35
9.2 calibration 36
9.3 Validation of methods 38
9.4 Summary of instrument- and matrix-specific
parameters 38
10.0 Data Quality and Reports 41
10.1 Proficiency testing 41
10.2 Rejection criteria and corrective action 43
10.3 Reports and record management 43
11.0 General Recommendations for an Analysis Protocol 45
12.0 Safety, Health, and Hazardous Waste 51
13.0 Bibliography 53
Appendix: Acronyms and Glossary of Terms 57
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EXECUTIVE SUMMARY
The hazards of Pb-based paint have become a leading public health issue of
the 1990s, and Pb-paint abatement of homes is a high priority among many different
health and environmental organizations. The Environmental Protection Agency (EPA)
estimates there are several hundred laboratories, not currently performing analysis,
that will be involved in new, extensive Pb-abatement programs.
Following the lead of the Interagency Lead-Based Paint Task Force (U.S. EPA,
1992), the EPA Office of Pollution Prevention and Toxics (OPPT) is establishing the
National Lead Laboratory Accreditation Program (NLLAP). The NLLAP will provide
federal oversight for state and private sector laboratory accreditation programs
involved in the accreditation of laboratories analyzing paint, soil, and dust samples
associated with the abatement and control of Pb-based paint contaminated housing.
The NLLAP will recognize accrediting organizations that meet NLLAP minimum
requirements through a Memorandum of Understanding (MOU). Each NLLAP-
recognized accrediting organization will administer its laboratory accreditation program
under NLLAP oversight. In order to be recognized by the NLLAP, laboratories must
meet the following criteria:
• The laboratory must successfully undergo a systems audit inclusive of an
on-site assessment by an analytical laboratory accrediting organization
recognized by EPA through an MOU.
• The laboratory must successfully participate in the Environmental Lead
Proficiency Analytical Testing (ELPAT) program.*
* The Environmental Lead Proficiency Analytical Testing (ELPAT) Program is a
cooperative effort to improve and evaluate the performance of laboratories involved in
the analysis of Pb in paint, dust, and soil matrices. The National Institute for
Occupational Safety and Health (NIOSH) performs ELPAT data analysis under a
Memorandum of Understanding (MOU No. PW593570-01-0) with the U.S.
Environmental Protection Agency (EPA). The American Industrial Hygiene Association
(AIHA) contracts for ELPAT sample production and administers the ELPAT program
as permitted under a Cooperative Research and Development Agreement (CRADA
No. NIOSH-92-1) with NIOSH covering cooperation in analytical research and
proficiency test programs.
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The purpose of this Laboratory Operations Guide is twofold: to provide
information for laboratory chemists performing analysis for Pb in paint, soil, and
deposited dust, including wipe samples and vacuumed dust; and to assist those
laboratories seeking accreditation.
The guideline was prepared following a working meeting of experts in metals
analysis from government and independent laboratories. It begins with a general
overview of the collection of paint, soil, and deposited dust samples so that the
laboratory staff will have a good understanding of the types of samples that will be
analyzed and will be able to provide the client with suggestions on field-sampling
procedures. Then issues such as laboratory management, personnel qualifications,
quality assurance, proficiency testing, analytical methods, and instrumentation,
relevant to the analysis of paint, soil, and deposited dust for Pb, are discussed.
Practical aspects of laboratory operations for these matrices are stressed. This
guideline provides specific recommendations that should be considered for
laboratories seeking NLLAP recognition for analyses of Pb in paint, soil, and dust
(including wipe samples and vacuumed dust).
XII
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SECTION 1
INTRODUCTION
1.1 BACKGROUND
The hazards of Pb-based paint have become a leading public health issue of
the 1990s. Pb-paint abatement of homes is a high priority among many different
health and environmental organizations. The Environmental Protection Agency (EPA)
estimates there are several hundred laboratories not currently performing these
analyses that will be involved in new extensive Pb-abatement programs.
1.2 EPA RECOGNITION OF LABORATORIES
Following the lead of the Interagency Lead-Based Paint Task Force (U.S. EPA,
1992), the EPA Office of Pollution Prevention and Toxics (OPPT) is establishing the
National Lead Laboratory Accreditation Program (NLLAP). The NLLAP will provide
federal oversight for state and private sector laboratory accreditation programs
involved in the accreditation of laboratories analyzing paint, soil, and dust samples
associated with the abatement and control of Pb-based paint contaminated housing.
The NLLAP will recognize accrediting organizations that meet NLLAP minimum
requirements through a Memorandum of Understanding (MOU). Each NLLAP-
recognized accrediting organization will administer its laboratory accreditation program
under NLLAP oversight. In order to be recognized by NLLAP, laboratories must meet
the following criteria:
• The laboratory must successfully undergo a systems audit inclusive of an
on-site assessment by an analytical laboratory accrediting organization
recognized by EPA through an MOU.
• The laboratory must successfully participate in the Environmental Lead
Proficiency Analytical Testing (ELPAT) program. (See footnote on page xi.)
The completion of a proficiency testing-based program alone is not sufficient
proof that a laboratory can perform successfully on real world samples. The
proficiency testing sample, even though it is a matrix-based material, will usually
receive special treatment in the laboratory. The systems audit is necessary to ensure
that a laboratory has the required staff, methods, facilities, quality assurance plans,
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and other essentials necessary to perform the analysis within a stated level of
confidence.
1.3 OTHER PROGRAMS
This guideline is limited to the analysis of Pb in paint film or chips, Pb-based
paint contaminated soils, and deposited dust (vacuum dust and wipe samples). There
are many programs covering Pb in other matrices. Some of these are Pb in air
(occupational and environmental), drinking water, eating utensils, solid waste,
hazardous waste, gasoline, and blood. Separate regulatory guidance is already in
place for Pb in these matrices. The guidelines in this document are intended to avoid
a duplication of efforts for existing programs.
1.4 PURPOSE
This laboratory guideline provides needed information for laboratory chemists
and laboratory managers in laboratories that seek accreditation for Pb in paint, soil,
and deposited dust matrices, including vacuumed dust and wipe samples. The
guideline identifies major issues that must be included in a laboratory training program.
It also provides minimum recommendations for good laboratory practices in a
laboratory that analyzes paint, soil, and deposited dust for Pb. The guideline should
help a laboratory make an informed commitment to participate in the NLLAP. When
finalized, the availability of specific quality system requirements for laboratories
wishing to participate in the NLLAP will be announced in the Federal Register.
Quality laboratories that understand the idiosyncracies of Pb analysis are
needed by federal agencies, including HUD and EPA. Data from these laboratories
must be of high quality to support decisions regarding the suitability of habitation in
buildings undergoing Pb abatement.
1.5 APPROACH
EPA was requested to develop a laboratory operations guideline for use by
laboratories that seek accreditation in the Pb-abatement area. A working meeting of
experts in metals analysis from government and from independent laboratories was
convened in Gaithersburg, Maryland, on June 24 to 26, 1992. Information gathered at
this meeting was compiled into this document.
This guideline includes a general overview of the collection of paint, soil, and
deposited dust samples in order that the laboratory staff will have a good
understanding of the types of samples that will be analyzed and can provide the client
with suggestions on field-sampling procedures. The guideline then addresses many
issues, such as laboratory management, personnel qualifications, quality assurance,
proficiency testing, analytical methods, and instrumentation, relevant to the analysis of
paint, soil, and deposited dust for Pb.
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This document builds on existing laboratory guidelines, such as the TSCA GLP
standards (U.S. EPA, 1989), and the various federal task forces and professional
committee reports recently published on the laboratory aspects of Pb. This document
includes a discussion of major issues related to Pb matrices and a glossary of
acronyms and terms. An extensive reference list is also included.
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SECTION 2
FACILITIES AND PERSONNEL QUALIFICATIONS
This section gives recommendations for facilities seeking to be accredited for
the analysis of paint, soil, and deposited dust for Pb, and requirements for the training
and experience of laboratory personnel.
2.1 FACILITIES
These laboratory guidelines apply to fixed location, temporary, and mobile
laboratories.
A laboratory should have the space, equipment, instruments, ventilation, utility
services, storage, safety equipment, and manuals necessary to accomplish Pb
analyses of paint, soil, and deposited dust. The facility should have restricted access
for security reasons and controlled access to sample preparation areas to reduce
contamination. Other recommendations are listed in the TSCA Good Laboratory
Practices Standards (U.S. EPA, 1989). Minimum recommendations for metals
laboratories include:
• Appropriate area for sample receipt, processing, and storage (secured,
controlled temperature).
• A laboratory hood for digestion of samples that meets the requirements
specified in the Industrial Hygiene Ventilation Manual of the American
Conference of Governmental Industrial Hygienists (ACGIH, 1991).
• An adequate number of grounded electrical circuits that meet local electrical
codes and ensure stable electrical supply to instruments and data systems.
Uninterrupted power supplies may be needed in some areas to protect data
systems.
• Ambient temperature and humidity control adequate to insure reliable
operation of instrumentation and sample/digest stability.
• Cross-contamination control procedures to prevent sample contamination
and contamination of work areas. Controlled access to sample preparation
areas and other procedures to minimize sample contamination.
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Documentation of effectiveness of contamination control by use of surface
wipe samples.
• A glassware-cleaning facility with SOPs and monitoring requirements.
• Approved procedures for disposal of hazardous waste.
2.2 PERSONNEL AND QUALIFICATIONS
The laboratory management should provide technical and quality managers who
operate the laboratory in conformance with ISO Guide 25 (ISO/IEC Guide 25, 1990),
NLLAP requirements, and the accrediting organization requirements. Following are
the personnel and minimum qualifications that are needed.
Technical Manager, or however named
This individual should have a B.S. degree in Chemistry, or related field, with a
minimum of 3 years' nonacademic laboratory experience, two of which are in
metals analysis. This individual is responsible for the technical effort and
should be available to the analyst at the laboratory at least 50% of the normal
work day. The technical manager may also serve as the inorganic chemistry
supervisor.
Quality Manager, or however named
This individual should have a B.S. degree in basic science and have at least
1 year of nonacademic analytical chemistry experience and training in statistics,
or 4 years nonacademic analytical chemistry experience and training in
statistics. Experience.pr knowledge of ISO Guide 25 is essential. The quality
manager should be separated from the analytical chemistry operations. In
some small laboratories, the technical manager may also function as the quality
manager as long as this person is not involved in the direct supervision of the
lead analyst/technician doing the routine sample analysis.
Inorganic Chemist, Spectroscopist, or however named
This individual should have a B.S. degree in Chemistry, or related field, with a
minimum of 1 year in metals analysis. Training in specific metals methods
used in the laboratory must be documented; proficiency in analysis must also
be documented. This category includes the following persons:
• Inductively Coupled Plasma-Emission Spectroscopist
Experience: 1 year minimum recommended (nonacademic)
Training: Satisfactory completion of a short course on ICP-AES. An in-
house training program is acceptable.
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• Flameless Atomic Absorption Spectroscopist
Experience: 1 year minimum recommended (nonacademic)
Training: Satisfactory completion of a short course on Graphite Furnace
Atomic Absorption (GFAA). An in-house training program is acceptable.
• Flame Atomic Absorption Spectroscopist
Experience: 1 year minimum recommended (nonacademic)
Training: Satisfactory completion of a short course on Direct Flame
Aspiration Atomic Absorption Spectrometry (FLAA). An in-house training
program is acceptable.
Analyst, Technician, or however named
Two years of technical education at the college level is recommended. This
individual must have documented training in specific metal methods used in the
laboratory and must have documented proficiency in performing assigned tasks.
This category includes the following persons:
• Inorganic Sample Preparation Technician
Experience: 3 months minimum recommended (nonacademic)
• Routine Sample Analyst (instrumentation)
Experience: 6 months minimum recommended (nonacademic)
The above staff must have documented training on instruments specific to the
laboratory and have demonstrated proficiency in these techniques. Junior staff, such
as analysts or technicians, must work under the direct supervision of a degreed
scientist in one of the "Chemist/Spectroscopist" categories. Junior staff may also work
under the supervision of the Technical Manager, or a sample analyst/technician who
has performed successfully over a period of three years in the analysis of metals,
using the same technologies that will be used for the analysis of Pb-containing
samples.
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SECTION 3
QUALITY ASSURANCE
Quality assurance programs are required for laboratories that analyze paint,
soil, and deposited dust for Pb. The ISO Guide 25 (ISO/IEC Guide 25, 1990), the
internationally accepted quality system for testing laboratories, should serve as the
basis of the laboratory quality system. There are several good general references for
quality assurance programs listed in the bibliography. The reference by Liabastre
(Liabastre, 1992) is recommended as it addresses all aspects of quality assurance for
environmental assessment laboratories. The reference by Ratliff (Ratliff, 1990) is also
recommended. Information specific for laboratories that analyze paint, soil, and
deposited dust for Pb is located in the HUD Interim Guidelines (HUD, 1990) and in the
other various referenced publications.
3.1 THE QUALITY SYSTEM
A laboratory must have a quality system documented in a quality manual. The
manual should document the policies and objectives of the quality system. The
specific program requirements are found in individual accrediting organization policies.
The major components of a typical quality system, which are listed below, should be
addressed and documented in a quality manual and in related supporting documents.
The components are listed according to ISO Guide 25 headings (ISO/IEC Guide 25,
1990).
• QA management should be directed by a full-time employee with power to
oversee the situation, identify problems, and make corrections, while being
independent of the analyses.
• A quality policy statement, including objectives and commitments by top
management.
• Organization and management structure of the laboratory, its place in any
parent organization, and relevant organizational charts.
• Relationship between management, technical operations, support services,
and the quality program.
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• Procedures to control and maintain documentation of the quality manual and
related supporting documents.
• Job descriptions of key staff and reference to other staff.
• The introduction of new employees to the quality manual and the
requirement that all employees periodically review the manual.
• A documented training program for employees that includes site-specific
SOPs.
• Identification of the laboratory sign-off person for reports.
• Traceability of calibration standards to SRMs.
• Scope of the laboratory operation and services offered.
• Procedures for review of incoming work to assure adequate facilities and
staff.
• Reference to the calibration, verification, and test procedures used.
• Procedures for handling calibration and test items.
• SOPs for sample log-in procedures.
• SOPs for sample preparation, including debris removal, substrate removal,
drying, grinding, sieving, and mixing.
• SOPs for sample and subsample identification, including digests and
extracts.
• SOPs for the preparation of working standards and calibration solutions.
• SOPs for digestion procedures, methods of analysis, and calibration
procedures.
• SOPs for major equipment calibration, reference standards used, and
maintenance of equipment.
• References to verification practices, including interlaboratory comparisons,
proficiency testing programs, use of reference materials, and internal quality
control schemes.
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• SOPs for feedback and corrective action whenever testing discrepancies are
detected, or departures from documented policies and procedures occur.
• Arrangements for exemptions permitting departures from documented
policies/procedures as specified in SOPs.
• References to procedures for dealing with complaints.
• References to procedures for protecting confidentiality of results.
• SOPs for data audit and review.
• Quality system audits should be conducted to ensure that the documented
quality system is implemented as written.
3.2 REVIEW OF THE QUALITY SYSTEM
The quality system requires frequent inspection and audits to ensure its
effectiveness. The following are recommendations for quality system audits.
• Quality system audits should be conducted at regular intervals by trained
and qualified staff to verify the system is implemented as written.
Discrepancies found should be corrected, and any client whose reported
data are affected should be notified in writing immediately.
• The quality system should be reviewed at least once per year by
management to ensure its continuing suitability and effectiveness and to
introduce any necessary changes or improvements.
• All audit and review findings, and any corrective actions that arise from them,
should be documented by the Quality Manager and resolved in a timely
manner.
3.3 QUALITY CONTROL
The quality manual and related supporting documents should contain the
following sections on quality control:
3.3.1 Quality Control System
• QC procedures required by applicable federal or state environmental or
public health agencies should be listed, documented, and followed.
• A sample tracking system must be maintained.
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• Control chart data or equivalent should be maintained for each analytical
technique. See Handbook for SRM Users (Taylor, 1985) for
recommendations on control charting.
• Supervisory personnel should review the data calculations and QC results
(internal data review).
• Deviations or deficiencies in QC should be reported to management
immediately.
• A documented corrective action plan should be implemented when analytical
results fail to meet QC criteria.
• QC data must be retrievable for all analytical results.
3.3.2 Calibration and Quality Checks
• Standard calibration curves should be prepared to adequately cover the
expected concentration ranges of the samples and the expected "action
levels' of Pb (HUD, 1990).
• Standard calibration curves should be prepared using at least three
standards and one blank, unless otherwise specified by the method.
• New calibration curves should be prepared whenever out-of-control
conditions are indicated and after new reagents are prepared and used.
• Method detection limits should be determined and documented (40 CFR136,
Appendix B).
• The laboratory should ensure the quality of results by implementing and
reviewing quality checks, as appropriate, but not limited to:
- Internal quality control charting based upon statistical techniques. This is
most useful for identifying trends and out-of-control incidents.
- Regular use of standard reference materials and certified reference
materials as primary reference materials.
- Participation in the ELPAT Pb-proficiency testing program.
- Replicate testings using the same or different methods.
- Re-testing of retained items as needed.
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3.3.3 SOPs
• The QC procedures (SOPs) should be specific to each test technology and
matrix addressing the following:
- Reagent and method blanks
- Glassware cleaning
- Trip and field blanks
- Sampling and subsampling
- Replicate/duplicate analysis
- Spiked and blank sample analysis
- Blind samples
- Quality control samples
- Control charts
- Calibration standards
- Reference samples and SRMs
- Internal standards
3.4 QUALITY CONTROL PRACTICES
The laboratory quality control program should include the continual evaluation of
its performance (system process control) for each matrix, which includes the
determination of accuracy and precision. One possible method used for laboratory
system process control is the use of control charts to monitor the performance of a
specific QC sample. Control charts should specify warning and action limits. In the
absence of a statistically sufficient data base to determine the necessary frequency for
QC samples, the laboratory should default to the use of a set frequency for QC
samples stated in its analytical standard operating procedure.
Quality control practices can be broken down into those processes that are
affected by the instrumentation and those that are related to the sample matrix. The
following recommendations for matrix-based quality control practices applicable to AA
or ICP-AES should be used in the absence of laboratory-based process control data.
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3.4.1 Precision and Accuracy Determinations
Accuracy studies are performed to determine how close a measurement comes
to an actual or accepted reference value. Accuracy can be expressed as percent
recovery and evaluated by analysis of matrix spike samples. A matrix spike is an
aliquot of a sample fortified (spiked) with a known quantity of the analyte of interest
and subjected to the entire analytical procedure. The spike should be prepared from a
standard stock, which is different from the calibration standard stock, and should have
a Pb concentration that is within the range of the sample to be run.
Precision is evaluated by the reproducibility of analyses. Precision is commonly
expressed as standard deviation or relative percent difference (RPD) and can be
evaluated by the analysis of replicate samples. Replicate sample analyses are one or
more additional analyses on separate portions of a given sample in order to assist in
the evaluation of method variance. Most commonly, two replicate analyses (defined
as a duplicate analysis) are performed.
In the analysis of soil, dust (vacuum) and paint chip matrices, samples may be
too small and difficult to homogenize and split in order to obtain samples for matrix
spike evaluations or replicate analyses. For these sample matrices, the laboratory
should select alternate QC options, such as the analysis of duplicate laboratory control
samples per batch.
Paint chips, soil, and vacuumed dust samples
Accuracy determination. Matrix spiked samples should be analyzed with a
minimum frequency of 5% of the samples for each matrix, per batch of samples
(samples processed at a single time). If there are fewer than 20 samples in a batch,
at least 1 spiked sample for each matrix per batch should be analyzed.
Precision determination. Replicate (duplicate) samples should be analyzed with
a minimum frequency of 5% of samples for each matrix per batch of samples. If there
are fewer than 20 samples in a batch, at least 1 sample for each matrix per batch
should be analyzed. In the event the analyte is not detected in the sample, replicate
matrix spike samples may be analyzed.
Dust wipe samples—accuracy and precision determinations
When analyzing wipe samples, method spike samples are prepared using blank
collection media and analyzed with a minimum frequency of 5% of samples for each
matrix per batch of samples. If there are fewer than 20 samples per batch, at least 1
method spike/spike duplicate set should be run per batch. The matrix samples are to
be prepared using a Pb-based paint NIST SRM applied directly to the wipe. It is
recommended that the client submit blank wipes representative of the lots to be used
in the field for lead contamination analysis prior to field sampling.
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3.4.2 Method Blanks
When using methods requiring sample pretreatment not performed on
calibration standards, a method blank containing all reagents and subject to all
preparation steps should be processed and analyzed along with the samples. Method
blanks should be analyzed with a minimum frequency of 5% of the samples for each
matrix per batch of samples. If there are fewer than 20 samples in a batch, at least 1
method blank for each matrix per batch should be analyzed. The use of method
blanks provides a measurement of laboratory and/or reagent contamination. Method
blanks are not to be used to correct sample results.
3.4.3 External Reference or Laboratory Control Sample Analysis
At least one external reference or laboratory control sample (LCS) should be
analyzed with each matrix per batch of samples with a minimum frequency of 5%. if
there are fewer than 20 samples per batch, then at least 1 LCS should be run per
batch per matrix type. The concentration of the LCS should be within the working
range of the method and should not require extensive pretreatment, dilution, or
concentration prior to analysis. Sources of these samples include but are not limited
to: NIST Standard Reference Materials, commercially available certified reference
samples, or samples prepared from different sources of analyte than calibration
standards and whose concentrations were determined using definitive methods. If
available, all these reference materials should be NIST traceable.
3.4.4 Recommended QC Sample Criteria
The following recommendations for analytical instrument quality control
practices should be used in the absence of laboratory-based process control data.
Acceptable performance limits for analytical instrumentation, as well as each
method, should be established based upon the continuing statistical evaluation of the
data generated by the analysis of quality control samples, unless specific minimum
acceptance limits are established by the method. The laboratory's calculation
procedures for statistically derived acceptance limits should be documented. Some
methods have listed acceptance criteria for applicable analytes based upon
determinations by a single laboratory, the compilation of data from many laboratories,
or limits that are assumed or expected. These limits may be too broad to define
accurate acceptance criteria for routine use. These limits are best used as guidelines
during the initial phases of method use and are superseded when the laboratory has
collected sufficient self-generated data for proper statistical evaluation.
In the absence of sufficient data for the determination of QC sample frequency
and acceptance criteria, the following minimum QC sample frequencies and
acceptance limits are recommended (where applicable) for analytical SOPs employing
AA or ICP-AES instrumentation:
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QC sample
Initial calibration
verification (ICV)
Initial calibration blank
(ICB)
Continuing calibration
verification (CCV)
Interference check sample
(ICS)
Continuing calibration
blank (CCB)
Laboratory control sample
(LCS)
Matrix spike
Duplicate sample
Method blank
Frequency
Once per run after
calibration
Once per run at the
beginning of run
Before and at the end of a
sample run, as well as
every 10 samples
Beginning and end of
each run or twice every
8hr
After each ICS and CCV
1 per 20 samples or batch
(5%)
1 per 20 samples or batch
(5%)
1 per 20 samples or batch
(5%)
1 per 20 samples or batch
(5%)
Acceptance limits
Within ±10% of known
value
Absolute value not
more than 20% of the
regulatory limit or level
of concern
Within ±10% of known
value for ICP or FLAA;
within ±20% for GFAA
Within 20% of known
value
Absolute value not
more than 20% of the
regulatory limit or level
of concern
Within ±20% of known
value
Within ±25% of known
value
Within ±25% relative
percent difference
(RPD)
Absolute value not
more than 20% of the
regulatory limit or level
of concern
A detailed recommended analysis protocol is listed in Section 11.
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SECTION 4
REQUIRED STANDARD OPERATING PROCEDURES (SOPs)
4.1 OVERVIEW
All methods, including sample collection, subsampling, digestion, and analysis,
should have laboratory-generated standard operating procedures (SOPs). There are
no standard methods from EPA or other organizations/agencies with published
validations for the analysis of Pb in paint and deposited dust matrices. There is a
standard method for the digestion of soils (U.S. EPA SW-846 Method 3050).
Modifications of methods must be documented in revised SOPs. Minor modifications,
for example, the use of more acid, should be specified in SOPs and include the
reasons to make such adjustments. No deviations should be permitted during routine
sample analysis beyond those limits specified in the laboratory SOP, but deviation
within stated limits is acceptable. Guidelines for the preparation of SOPs have been
published by the EPA Office of Solid Waste (U.S. EPA, 1990c).
4.2 ELEMENTS OF SOPs
SOPs for analytical methods should address the following basic elements:
Scope and application of the laboratory method
Summary of the method
Definitions and abbreviations
Interferences
Safety considerations
Apparatus and equipment
Reagents and consumable supplies
Sample collection, preservation, and storage
Sample preparation (debris removal, substrate removal, drying, grinding,
sieving, and mixing)
Instrument calibration
Quality control procedures (internal and external)
Detailed step-by-step procedure
Sample calculations
Method performance, including accuracy and precision
References
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SECTION 5
FIELD SAMPLING
5.1 OVERVIEW
Laboratories that perform analyses of Pb in paint, soil, and deposited dust will
generally not be involved in the sample collection phase; therefore, specific knowledge
of sample collection is not needed. This section provides the laboratory chemist with
a general understanding of the sampling procedures so that:
• There is a better understanding of the nonuniformity of the sample that
arrives at the laboratory;
• There is an understanding of the types of samples, contaminants, and debris
that may arrive at the laboratory;
• The laboratory is able to recommend minimum sample sizes to the client to
ensure that there is sufficient sample to meet analytical requirements, such
as minimum detection limits, spike samples, and duplicate analyses; and
• The laboratory can better comply with TQM principles by knowing the entire
history of the sample from collection site to report (the process).
The HUD Interim Guidelines (HUD, 1990) and the HUD Risk Assessment
Protocol (HUD, 1992) provide recommended sampling protocols for the collection of
paint chips, dust, soil, and airborne Pb dust.
Some laboratories may be asked to perform actual field sampling. In those
cases, the HUD Interim Guidelines need to be studied thoroughly to develop the
appropriate sampling strategies to comply with their directives. Laboratories that may
also be asked by their clients for recommendations on sample collection need to be
prepared to offer suggestions, if asked.
5.2 MINIMUM SAMPLE SIZE
The minimum sample size collected is based on the ability to detect Pb at the
action level recommended in the HUD Interim Guidelines (HUD, 1990) with a defined
degree of confidence. There are no federal standards at present, but the HUD
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"clearance" guidelines (Section 10.4.3) provides the following guidance for dust
collected with a wipe sample:
• 200 u.g Pb/sq ft for floors (includes carpet)
• 500 u,g Pb/sq ft for window sills
• 800 n,g Pb/sq ft for window wells
The HUD Interim Guidelines (HUD, 1990) recommendation for Pb in paint film
is 1.0 mg/cm2 or 0.5% by weight. The Consumer Product Safety Commission (CPSC)
limit for Pb in paint film, established in 1978, is 0.06%. Recently, a proposal was
made by CPSC to reduce the Pb content of paint to 0.01% by weight (Federal
Registers?, 18418, April 30, 1992). CDC suggests that 500-1000 |ig/g of Pb in soil
leads to elevations in blood Pb in children (CDC, 1991). ASTPHLD suggests that if a
child with a blood Pb level of zero ingests 1 g of soil containing 1000 mg/kg Pb, then
the blood Pb level of the child could rise to 10 ug/dL, the current CDC action level.
ASTPHLD suggests that a soil Pb level of less than 200 u.g/g (200 mg/kg) would not
result in a significant elevation of blood Pb level in children, unless an unusually large
amount of soil is ingested (ASTPHLD, 1991).
The recommended minimum sample size to submit to the laboratory is:
• Soil: 1.5g
• Dust: 300 mg
• Wipe: 1 wipe used to sample dust in a 1 sq ft area
• Paint: 300-mg paint chips
The absolute minimum sample size needed for analysis taken from a submitted
sample using FLAA methods is:
• Soil: 0.5 g or as specified in the digestion procedure
• Dust: 100 mg.or as specified in the digestion procedure
• Wipe: 1 wipe taken over a 1 sq ft area or as specified in the digestion
procedure
• Paint: 100 mg or as specified in the digestion procedure
The minimum sample size is dependent on the concentration of Pb in the
sample, on the dilution of the digested Pb containing sample prior to instrumental
analysis, and on the instrumental method of analysis. Wipe samples containing less
than 200 u,g Pb/sq ft (the HUD, 1990 clearance value) may not be detected with FLAA
if only 1 sq ft is sampled and the final digest volume is 100 mL Adequate sensitivity
exists for other matrices. GFAA and ICP-AES have adequate sensitivity, even at
clearance levels and minimum sample size recommendations.
Minimum sample sizes required for other sources of Pb, such as from steel
structures and non-HUD buildings, must be determined from relevant guidelines.
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5.3 WIPE SAMPLING
5.3.1 Acceptable Criteria for Wipes
There should be minimum wipe sample acceptability criteria that would either
specify acceptable dust wipe media for collection of deposited dust samples or require
laboratory evaluation of the collection media for blanks and digestion recovery/
interference. If a laboratory is to accept a sample for analysis in a matrix other than
specified in this guideline, it must develop an SOP as described in Subsection 6.2.
5.3.2 Characteristics of a Good Wipe
• Durability during sample collection. The wipe should not disintegrate during
the sampling process.
• Controlled background. The wipe should be made to rigid specifications
regarding its background levels of Pb from the manufacturing process.
ASTM Subcommittee E06.23 suggests a Pb level of < 5 u.g Pb/wipe.
• Digestibility of the wipe should be compatible with analytical sample
preparation SOPs and leave little or no residue.
• Wipes should have good dust pickup capacity and not just "push the pile of
dust around the surface."
• Wipes should be individually-wrapped and pre-moistened, or there should be
a well-defined sampling protocol for multiwipe dispensers in order to minimize
contamination.
5.3.3 Wipe Sampling Recommendations
Procedures for collection of wipe samples are detailed in the HUD Interim
Guidelines, Appendix A5-24 (HUD, 1990). Details are also given in the HUD Risk
Assessment protocol (HUD, 1992), pp. 28926-28927. An SOP for wipe sample
collection must be followed. The type of wipe is not specified in the HUD Interim
Guidelines (HUD, 1990), which creates a difficulty for the laboratory, because a variety
of dust wipe samples are likely to arrive in the laboratory. Wipes, including "baby
wipes" (including those containing lanolin and aloe), gauze pads, filter paper, napkins,
"wet naps," alcohol swabs, and duct tape, have been received to date in some
laboratories offering Pb analyses. The laboratory should request the following
regarding all wipe samples:
• Rigid contamination control should be maintained by (1) use of an individually
wrapped pre-moistened wipe, or (2) use of wipes from a multiple dispenser
pack accompanied by a specific protocol.
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• Unused wipes should be submitted to the laboratory for (1) Pb blank
determination and (2) digestibility studies. If existing SOPs include digestion
data for the submitted wipe, then only a Pb blank determination is necessary.
• If wipes from a dispenser pack are used, the HUD sampling guidelines
should be followed. (Discard first wipe and handle wipes with gloved hand to
avoid contamination. Each new wipe sample should be handled with a clean
glove to avoid cross-contamination.)
5.4 PAINT CHIPS
The HUD Interim Guidelines (HUD, 1990) and the HUD Risk Assessment
Protocol (HUD, 1992) provide sampling protocols. An SOP for paint chip collection
must be followed. The laboratory should request that those collecting the paint chips
adhere to the following recommendations:
• Collect paint chips free of other debris, if possible.
• Remove as much substrate as possible, if necessary, because results may
be expressed as Pb per weight.
5.5 DUST—VACUUMED SAMPLES
The HUD Interim Guidelines (HUD, 1990) do not suggest protocols for
collection of vacuumed dust, and there are no published guidelines. The procedure
for the collection of vacuumed dust samples should be detailed in an SOP.
5.6 SOIL SAMPLES
The HUD Interim Guidelines (HUD, 1990) and the EPA (U.S. EPA, 1990c) have
protocols for collection of soil samples. Generally, the soil sample represents a
composite of samples collected from several adjacent areas and at different depths.
Soil collection should be detailed in an SOP.
5.7 BLANKS AND BACKGROUND SAMPLES
The HUD Interim Guidelines (HUD, 1990) suggest some of the types of field
blanks and background samples that should be submitted to the laboratory. The
collection of blanks and background samples should be covered by an SOP. The
suggestions below are based on good laboratory practice for metals laboratories.
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5.7.1 Blanks
The following types of blanks should be submitted to the laboratory.
Field blank:
Rinseate blank:
Trip blank: A clean sample, including collection media, that is carried to the
sampling site and transported back to the laboratory for analysis
without being opened. This blank is analyzed as a regular
sample through all steps. The trip blank evaluates the integrity of
the sample container.
A clean sample of matrix (e.g., paint, soil, dust, or wipe) carried to
the sampling site, exposed to the sampling conditions (e.g., bottle
caps removed) and returned to the laboratory, treated as an
environmental sample, and carried through all steps of the
analysis. For example, clean quartz sand, non-Pb containing
paint, or a clean wipe could be used as a field blank matrix. The
field blank evaluates possible site contamination sources such as
airborne contaminants.
A sample of a "used" cleaning fluid rinse solution, also called an
equipment blank. Rinseate blank examples include a final rinse of
the device used to collect soil or vacuumed dust or the final rinse
to clean a scoop used to collect soil or vacuumed dust samples.
The rinseate blank is used in rinsing collection media and
equipment prior to use to monitor possible cross contamination.
The rinseate blank goes through all steps in the analysis including
the digestion.
5.7.2 Background Samples.
A background sample is a sample of matrix collected at or near the site that is
uncontaminated with Pb from paint. It is often difficult to obtain a true background
sample in the field; therefore, the collection of background samples is not
recommended.
5.8 DUPLICATE FIELD SAMPLES
The HUD Interim Guidelines (HUD, 1990) suggest collection of "duplicate"
samples adjacent to areas of concern. This term is incorrectly used (see Glossary)
since "duplicate" implies a uniform distribution of sample. The distribution of Pb in
paint, soil, and dust is not uniform; therefore, the usage of the term "duplicate" is
incorrect. A second sample could be collected in an adjoining area to provide a better
representation of Pb deposition, but this is not a duplicate sample.
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SECTION 6
LABORATORY SAMPLING
This section covers the handling of the sample after it is received from the field
and prior to digestion. Cleanup activities (removal of rocks, substrate, hair, etc.) and
subsampling or aliquoting of the bulk sample into uniform portions suitable for analysis
are also covered. Subsection 6.6 gives recommendations for sample tracking and
storage.
6.1 SOLIDS—GENERAL CONSIDERATIONS
Particle size distribution, debris, and stratification of solid samples is a major
problem. The following general considerations apply to all solid samples.
• Samples must be examined for debris, such as hair, paper clips, pins, and
insects, prior to subsampling the sample. Debris should be removed with
tweezers or by screening through a course #4 mesh (4 to 7 mm) sieve.
• Samples of dust or finely ground paint or soil are subject to stratification from
vibration in the laboratory. Therefore, thorough mixing is essential prior to
removing an aliquot for analysis.
• A representative sample must be obtained. A device such as a "riffle" box,
or equivalent, should be used for separating and allocating fractions of dust
or soil that have been ground to a #10 mesh (1.9 mm) and sieved. A riffle
box randomly aliquots one-half of the sample to one side and one-half of the
sample to the other. Several passes may be necessary to reach usable
sample sizes for digestion.*
• Humidity control is very important in sampling of solids, particularly if results
are expressed on a weight basis. Oven drying at 105°C to a constant weight
is recommended.
* Use of a riffle box to separate coal and coke is described in ASTM Method (D5).
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6.2 WIPE SAMPLES
The handling of wipes in the laboratory should be detailed by an SOP. Wipes
are used to collect deposited dust over a defined surface area. In most cases, the Pb
content in the wipe material is unknown and appears to vary from lot to lot and among
suppliers. The pickup efficiency (ability to pick up and retain dust on the wipe
material) and the digestibility properties are also unknown. Research on the
development of standardized wipes is in progress. Until such time as some
"standardized wipe" is developed, the laboratory must perform the following tests on
each type of wipe submitted.
• Determine the Pb background level in the "blank" wipe submitted with the
samples. Ideally, Pb background levels of wipe samples should be deter-
mined prior to sample collection. If the background level is greater than 5 u.g
Pb per wipe, blank correction may be necessary. Blank correction can be
used if the blank is < 20% of the regulatory limit or level of concern. If blank
correction is used, it must be documented on the report. It should be noted
that blank values of 5 u.g per wipe are insignificant at HUD clearance
recommendations of 200 u.g per wipe collected over a 1 sq ft area.
• Perform a recovery study of a spiked wipe (extractable Pb) using the
laboratory standard digestion technique. The digestion technique does not
have to destroy wipe fibers (total Pb) but should be able to digest Pb from
dust deposited on the wipe (extractable Pb).
Results should be expressed per wipe or per area sampled. If the area is less
than 1 sq ft, results should be corrected and reported as fig Pb/sq ft.
6.3 PAINT CHIPS
Appropriate steps must be taken to ensure uniformity of the sample before
subsampling. The presence of "substrate" compromises the results, particularly if the
results are presented on a weight basis. The handling of paint chips must be covered
by an SOP. Because paint chips containing substrate present special problems, the
following should be addressed:
• Attempts should be made to remove the paint from substrate. If the paint
cannot be removed from the substrate, the analytical report must include an
annotation that results may be invalid. Substrate contamination of paint must
be noted because large amounts of nonlead containing substrate will produce
low lead concentrations and may lead to false negative results.
Paint chips relatively free of substrate should be handled as follows:
• Cut paint chips into small pieces with scissors or a knife.
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• Grind up the pieces of paint chips into a powder with a mortar and pestle or
other nonmetal contaminating material to improve digestibility. Paints with a
high latex content may not be suitable for grinding due to their tendency to
form "gummy" residues.
6.4 DUST—VACUUMED SAMPLES
There are no defined procedures for preparation of vacuumed dust samples.
An SOP must be developed covering the steps listed below.
• Dust samples should be sieved (#10 mesh, 1.9 mm) to remove debris (metal,
glass, hair, pins, etc.) prior to digestion because this debris is not dust.
• Dust samples must be subjected to humidity control. If dust is moist, it
should be dried in an oven at 105°C to a constant weight. Cross-
contamination during drying can be reduced by placing dust samples in
covered drying bottles.
6.5 SOILS
The handling of soil samples should be covered by an SOP that addresses:
• Screening to remove debris, including metal, glass, plant material, rocks,
plaster, and bricks. If large paint chips are present in the soil, these should
be removed and digested separately.
• Drying of the soil at 105°C to a constant weight to control for variable
moisture content.
• Grinding to a fine mesh (#10) to aid digestion.
• Thorough mixing prior to analysis to avoid stratification.
6.6 SAMPLE TRACKING AND STORAGE
A sample tracking system should be detailed in an SOP and referred to in the
QA manual. A subsampling system of unique numbers should be used for all digests
and dilutions of the original sample so that original sample identification is not lost. If
computer log-in procedures are used, the sample log-in procedure should include hard
copy backup of computer log-in records. Although a legal chain of custody is not
usually required, a client may demand it in some cases that may involve potential
litigation.
The SOP should detail the specifics for storage of unused samples during the
analysis cycle and after completion of analysis. Digests can be kept for 2 to 4 weeks,
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as long as digest volumes are monitored gravimetrically for evaporation loss. Holding
times for matrix samples are not a problem. It is recommended that the laboratory
establish an automatic discard date for digests and samples, such as 90 days after
reporting to the client, unless contacted by the client.
The requirements for storage of samples and digests include:
• Secure storage in a locked or controlled-access area.
• Uniform environmental conditions must be maintained, such as a cool, dry
storage area.
• Storage of digests require special conditions. Fluid loss in digests by
evaporation should be monitored gravimetrically.
28
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SECTION 7
SAMPLE DIGESTION PROCEDURES
At this time, there are no standard EPA-approved digestion methods for paint
and dust matrices. EPA SW-846 Method 3050 is approved for soils, but not
necessarily for analysis of Pb in soils contaminated with paint chips. There are three
basic sample digestion techniques that have been applied, often with some
modification, to digest paint chips, dust (wipes and collected dust), and soil samples.
These methods are outlined below and cited in Section 9.0. However, little published
information is available to document the suitability of these digestion methods.
• Dry ashing followed by wet digestion with HNO3 or HNOJH2O2
• Wet digestion using a hot plate with HNO3 or HNO3/H2O2
• Microwave digestion with HNO3, HNOg/HCI, or
Dry ashing is hot recommended because it is difficult to control and has the
possibility of uneven heating and splatter/cross-contamination of samples. Therefore
'wet digestion" techniques are preferable. "Wet digestion" techniques using HNO3
alone are not generally recommended because digestion may be incomplete. Wet
digestion techniques, such as U.S. EPA SW-846 Method 3050, a validated method for
soils, are suggested and may be suitable for digestion of most samples. But this
method has not been validated for other matrices. NIOSH Method 7082 is also
suitable for digestion of dust samples. Perchloric acid has also been used in
combination with nitric acid with acceptable results. However, since the use of
perchloric acid requires special safety precautions (i.e., a perchloric acid hood), it is
generally not recommended.
Research is currently underway to develop a standard digestion procedure that
would work with all matrices using 200-250 mg of sample. The ASTM has prepared
draft wet digestion methods for wipes, dust, soils, and paint chips, which are currently
undergoing review and testing. Digestion acids should be chosen with analytical
instrumentation in mind because of incompatibility of HCI with GFAA instrumentation.
Whatever digestion technique is used, it is recommended that the digest be filtered or
29
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centrifuged prior to instrumental analysis. The specified digestion procedure should be
documented in an SOP.
Other methods, including digestion with perchloric and hydrofluoric acids and
fusion with lithium metaborate, have been suggested, but are not recommended for
general use because of safety considerations.
30
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SECTION 8
INSTRUMENTATION
Three general types of instrumentation are suitable for analysis of Pb in paint,
soil, and dust matrices. These are listed below and are available from a variety of
vendors in many different configurations.
8.1 ATOMIC ABSORPTION SPECTROMETRY USING DIRECT FLAME
ASPIRATION
This instrumentation, which is widely available with and without autosamplers,
has adequate sensitivity for most samples, depending on dilution volumes used in the
digestion process. Following are characteristics of FLAA:
• Instrument detection limits: Instrument detection limits are adequate for most
samples, but are the highest of the three techniques considered in this guide.
Since direct aspiration is required, a minimum of 5 mL of digest is needed for
aspiration and measurement of a stable signal.
• Principal interference: Light scattering and molecular absorption by matrix
components are common for measurements near detection limit and can
cause a false positive signal. They can best be corrected using methods
such as a continuum source or Zeeman background correction schemes.
Correction using alternate nonabsorbing Pb lines is possible but not optimal.
Matrix enhancement or suppression of the Pb absorbance signal is possible
at all concentration levels and can be corrected by using the method of
standard additions.
• Cost: Initial instrument cost is low and consumables, such as acetylene gas,
are inexpensive.
• Sample throughput: Sample throughput is good using either autosamplers or
manual aspiration and can be several samples per minute.
• Maintenance and potential downtime: Routine maintenance is limited to
periodic cleaning of the aspirator, mixing chamber, and burner, as well as
external optics as necessary. Of the three methods, maintenance and
potential downtime is lowest.
31
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• Principal Pb lines: The 283.3-nm line is preferred because of less molecular
absorption and scattering. The 217.0-nm line, however, is more sensitive
and can be used if a continuum source background correction is employed.
• Range of analysis: The linear range of analysis is approximately two orders
of magnitude, from about 0.2 u.g Pb/mL to 20 u.g Pb/mL, but can be extended
by rotating the burner head.
• Potential problem areas: The method detection capabilities are borderline for
wipes below HUD "Clearance" levels. For such samples, the 217.0-nm line
and background correction must be used.
8.2 ATOMIC ABSORPTION SPECTROMETRY USING THE GRAPHITE FURNACE
This instrumentation is widely available and is the most sensitive technique of
the three techniques. Throughput is good with autosamplers and sample size
requirements are very small. The following are GFAA characteristics:
• Instrument detection limits: Detection limits are the lowest of the three
instrumental techniques. Because only 20 u.L of sample are used for
analysis, digest volume requirements are the smallest (10 to 25 mL). If the
laboratory is also involved with blood Pb determinations, GFAA is the
instrumentation of choice.
• Principal interference: Light scattering and molecular absorption by matrix
components are common for most measurements and can cause a false
positive signal. They can best be corrected by methods such as a continuum
source (Deuterium Arc) or Zeeman or Smith-Hieftje background correction
schemes. Matrix enhancement or suppression of the Pb absorbance signal
is often significant and can be corrected by using the method of standard
additions. Matrix modifiers, such as magnesium nitrate, lanthanum nitrate,
palladium, or ammonium dihydrogen phosphate, minimize loss of Pb during
the sample charring step and allow higher charring temperatures. This also
minimizes, but does not eliminate, matrix enhancement or suppression
effects. Chloride arising from the use of HCI in a digestion can cause
significant interferences in GFAA.
• Cost: Initial instrument cost is intermediate. Maintenance and consumable
costs are significant, since the graphite furnace tubes must be replaced
approximately every 500 firings and argon gas must constantly flow through
the system to prevent oxidation of the graphite.
• Sample throughput: Autosamplers are required to increase precision and
throughput. Manual sample introduction is tiresome and often irreproducible.
Throughput is approximately one sample every 2 to 3 min.
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• Maintenance and potential downtime: The primary difference between
maintenance of GFAA and FLAA is the alignment and cleaning of furnace
components of the former. Because of the complexity of some graphite
furnace systems, downtime may be greater than with FLAA.
• Principal Pb lines: The 283.3-nm line is preferred because of less
interference. The 217.0-nm line, however, is more sensitive and may be
used as needed, provided the interference and noise are not severe.
• Range of analysis: The linear range of analysis for an intermediate sample
size is from about 0.001 u.g Pb/mL to 0.1 u.g Pb/mL, but can be varied by
adjusting sample size and dilution.
• Potential problem areas: Matrix interference and contamination.
• Advantages: This instrumentation is widely available and is the most
sensitive technique of the three. Throughput is good with autosamplers and
sample size requirements, are very small.
8.3 INDUCTIVELY COUPLED PLASMA EMISSION SPECTROMETRY
This instrumentation is available in many laboratories and offers the advantage
of simultaneous multielement determinations. Sensitivity for Pb is intermediate, but
adequate for all Pb matrix samples. Sample volume requirements are moderate
because the digest is aspirated into the plasma torch.
• Instrument detection limits: Instrument detection limits, which are similar to
the FLAA technique, are adequate for most samples, but may present
analysis difficulties at the lowest level of wipe samples. Because the direct
aspiration rate of ICP-AES is less than FLAA, less sample is required. If
other elements are desired in environmental samples, this is the
instrumentation of choice.
• Principal interference: Spectral interferences caused by radiation from lines
of other elements present in the sample are most common and can be
corrected by several methods. Background correction can be performed by
selecting wavelengths near the Pb line, or an alternate Pb line can be used.
It is important to include an interfering element check sample that contains
high levels of suspected elements (aluminum, titanium, chromium, calcium, or
iron).
• Cost: Initial instrument cost is high, but major consumable cost is only argon
gas, unless the instrument is operated incorrectly and the torch is destroyed.
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• Sample throughput: Sample throughput is intermediate between FLAA and
GFAA. Samples that are directly aspirated require a longer period for
equilibration and washout. Throughput is typically slightly less than one
sample per minute.
• Maintenance and potential downtime: Maintenance costs are the highest of
all the instruments discussed because of the complicated design of ICP-AES
instruments and the requirements for critical alignment of components.
• Principal Pb lines: Usually the 220.35-nm line is used, although an alternate
line is at 217.0 nm.
• Range of analysis: The linear range of analysis for the 220.35-nm line is
from about 0.2 \ig Pb/mL to 3,000 u.g Pb/mL
• Potential problem areas: Spectral interferences from high levels of other
metals and insufficient washout of mixing chamber can occur after the
analysis of a sample of high Pb concentration.
• Advantages: This instrumentation is available in many laboratories and offers
the advantage of simultaneous multielement determinations. Sensitivity for
Pb is intermediate, but adequate for all Pb matrix samples. Sample volume
requirements are moderate because the digest is aspirated into the plasma
torch.
8.4 OTHER INSTRUMENTATION
In addition to these instruments, there are others that are not currently
recommended. X-ray fluorescence (XRF) is currently being evaluated for laboratory
use and may be suitable. However, sample preparation steps, including sample load-
ing, can significantly affect precision and bias. Inductively Coupled Plasma-Mass
Spectrometry (ICP-MS), although a powerful and sensitive technique, is not recom-
mended at this time because of a lack of need for this level of instrumentation
sophistication and costs. Anodic stripping voltametry may be suitable, provided that
the method is compatible with digestion techniques. Methods using spectrophoto-
metric instrumentation for Pb, such as the dithizone method, are not recommended
because of the potential for contamination and interference. The latter method also
may not be compatible with digestion procedures.
34
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SECTION 9
ANALYTICAL METHODS AND CALIBRATION
This section gives a list of published methods and discusses calibration
standards applicable to paint, soils, and deposited dust matrices. References from
agencies of the Federal Government can be obtained from the National Technical
Information Service (NTIS), (703) 487-4650.
9.1 LIST OF METHODS
Many of these methods have not been validated with paint, soil, and deposited
dust matrices.
AOAC 5.009 (1984) - Lead in Paint Using Direct Aspiration Atomic Absorption.
ASTM D-3335-85a - Test Method for Low Concentrations of Lead, Cadmium,
and Cobalt in Paint by Atomic Absorption Spectrometry (direct
aspiration).
ASTM D 3618 - Test. Method for the Detection of Lead in Paint/Dried Paint Films.
U.S. EPA Reference Method for the Determination of Lead in Suspended
Particulate Matter Collected from Ambient Air (40 CFR Part 50,
Appendix G).
NIOSH 7082, Lead in Air Collected on Cellulose Ester Filters. Nitric acid/
hydrogen peroxide hot plate digestion followed by direct aspiration atomic
absorption at 283.3 nm.
NIOSH 7105, Lead in Air Collected on Cellulose Ester Filters, Nitric/Hydrogen
Peroxide Hot Plate Digestion Followed by GFAA.
NIOSH 7300, Elements in Air Collected on Cellulose Ester Filters, Nitric/
Perchloric Acid Hot Plate Digestion Followed by ICP-AES at 220.4 nm.
*U.S. EPA SW-846 Method 7420, Pb - Atomic Absorption, Direct Aspiration
(U.S. EPA, 1990c).
* These methods do not include a digestion technique and are for digests of Pb
prepared by one of the digestion techniques listed above.
35
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*U.S. EPA SW-846 Method 7421, Pb - Atomic Absorption, Graphite Furnace
(U.S. EPA 1990c).
*U.S. EPA SW-846 Method 601OA, Metals - Inductively Coupled Plasma
Emission Spectroscopy (U.S. EPA 1990c).
** U.S. EPA SW-846 Method 3050A - Acid Digestion of Sediments, Sludges and
Soils (Metals) (U.S. EPA 1990c).
**U.S. EPA SW-846 Method 3051 - Microwave Assisted Acid Digestion of
Sediments, Sludges, Soils and Oils (Metals) (U.S. EPA 1990c).
In addition to these cited methods, the ASTM E36 subcommittee is working on
several standard methods for Pb. These include GFAA, FLAA, and ICP-AES. These
draft methods include digestion techniques for paint, dust, wipes, and soil and include
hot plate wet digestion techniques and microwave digestion methods. These draft
methods are not yet available for distribution.
9.2 CALIBRATION
9.2.1 Primary Standards
Primary standards are solutions of standards that are traceable to aqueous-
based SRMs from NIST and should be used for instrument calibration. The
preparation of primary standards should be detailed in an SOP. The SOP should
detail the traceabilrty of the primary standard to primary calibrant SRMs from NIST.
The NIST aqueous 10,000 ppm Pb (in 10% HNO3) SRM is suitable for calibrant
material and should be used to check laboratory working standards. The SRM is
available as SRM 3128 (50 ml of a 10 mg/mL solution in 10% HNO3). Matrix-based
SRMs are not primary standards and are not suitable for instrument calibration.
9.2.2 Working Standards
Stock primary standards must be prepared from material traceable to NIST
SRM 3128. These stock standards are stable, but are subject to evaporation and loss
of Pb to the container wall. The possible loss of solvent can be monitored by
weighing the stock solution at regular intervals. The preparation of stock and working
standards, including storage conditions, should be detailed in an SOP. Acids used in
standards should match the acids used in the matrix. Purchased stock standards
should include certifications that standards are traceable to SRM-3128.
** These methods are general digestion techniques for the matrices listed. The
mild conditions used in SW-846 methods must be evaluated for their efficiency in
digesting these matrices. They must be combined with an analytical method such as
the EPA SW-846 Methods 601 OA, 7420, or 7421 for completion of analysis.
36
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Working standards should be prepared from stock primary standard solutions of
1,000 to 10,000 ppm Pb. Working standards are used for initial calibration of the
instrument and to verify the calibration at intervals dependent on the instrumental
method. The recommended minimum intervals are at the beginning, midpoint, and at
the end of a batch of samples (usually 20 samples) run on any particular day. Results
that are reportable should be in the calibration range.
9.2.3 Matrix-Based Quality Control Samples
A variety of matrix-specific materials (LCS) contain Pb and can be used for
quality control samples. These internal QC samples must be independent of the
instrument calibrant and used only to monitor the performance of the entire process,
including the digestion step.
9.2.4 SRMs from the NIST
NIST prepares a variety of SRMs. These reference materials are rigorously
characterized and analyzed by definitive methods. They are expensive and are not
intended to be used for routine quality control. They are intended to be used in the
development and validation of methods and as a real-world tool to evaluate method
performance. Examples of NIST SRMs available for Pb-based matrices are listed in
the table below. Certificates are available from NIST.
SRM
1579a
a
a
1648
2704
2709
2710
2711
2579
Description and date
Powdered Pb-based paint, Feb. 3, 1992
Powdered Pb-based paint (in progress)
Powdered Pb-based paint (in progress)
Urban participate matter, Nov. 16, 1978
Buffalo River sediment, July 9, 1990
Baseline agricultural soil, Oct. 16, 1992
Highly contaminated soil, Oct. 16, 1992
Moderately contaminated soil, Oct. 16, 1992
Lead paint film on Mylar sheet, set of 5,
July 27, 1992
Certified Pb value
11. 995% ±0.031
4.0%
0.5%
0.655% ± 0.008
161 u.g/g±17
18.9u.g/g±0.5
5532 u,g/g ± 80
1162u.g/g±31
3.53 mg/cm2 ± 0.24
1 .63 mg/cm2 ± 0.08
1 .02 mg/cm2 ± 0.04
0.29 mg/cm2 ± 0.01
< 0.0001 mg/cm2
These NIST SRMs are under development.
37
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9.2.5 Other Reference Materials
Reference materials from other sources are available, but they are not NIST-
certified and may be less well-defined and characterized. However, they may be
suitable for use as internal quality control materials.
There are three CRADA certified materials available. They are labeled: "This
product was verified for accuracy and stability under a cooperative research and
development agreement (CRADA) with the U.S. Environmental Protection Agency."
They are manufactured by Resource Technology Corporation, Laramie, Wyoming, and
are available from Fisher Scientific. These reference materials have also been
certified by A2LA. Current research is being conducted to better characterize the
homogeneity of these materials. These materials are not characterized like SRMs and
cannot be used as substitutes for NIST SRMs. Their characteristics are shown in the
following table.
No.
SRS 013-50
SRS 006-50
SRS 014-50
Description
Paint Blasting Waste
Paint Sludge
Bag House Dust
Certified concentration
643.2 + 1 29.4 ppm
753.0+1 14.7 ppm
191 4.2 + 41 0.6 ppm
ELPAT samples may be available for use in evaluation of method performance. Call
(703) 849-8888 for more information.
9.3 VALIDATION OF METHODS
Analytical methods should include validation studies conducted with matrix-
based SRMs, if available, or with other matrix-based reference materials. Guidelines
for analytical methods validation studies have been published in the Journal of the
Association of Official Analytical Chemists International (JOACI, 1989).
9.4 SUMMARY OF INSTRUMENT- AND MATRIX-SPECIFIC PARAMETERS
9.4.1 Instrument-Specific Parameters
The following table is a summary of typical instrument-specific parameters
identified by the working group.
38
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Parameter, instrument-
specific
IDL (ng/mL)
MDL (u.g/g)«e
Interference, spectral1'
Interference, matrix
and corrective action6
Sample size, preferred
Sample size, lab
minimum6
ICP-AES
0.05
5
Al, Cr, Ti, Ca, Fe
Possible.
Matrix-matching
internal standards
600 mg
200 mg
FLAA
0.03
3
not common
Common.
Method of
standard
additions
750 mg
250 mg
GFAA
0.001
0.1
not common
Common.
Matrix modifiers and
background correction;
method of standard additions
150 mg
50 mg
MDL: Calculation: see 40 CFR136, Appendix B.
Interference, matrices: Other matrices, such as the substrate and debris (hair, glass, sticks,
needles, insects, etc.), will interfere rf not screened or removed from the matrix of interest.
These values will vary depending on the digestion procedure used, the final volumes, and
sample sizes.
9.4.1.1
Precision, Accuracy, and QC Frequency—
Precision, accuracy, and frequency of QC should be nearly the same for all
methods. Precision and accuracy should be charted for the particular measurement
system with performance characterized by an SOP. Generally precision for all
methods is about ±10% at 5X MDL. Accuracy, measured as percent recovery, varies
from 85-115%.
Matrix spikes and QC check samples independent of the calibrant should be
run at a minimum frequency of 5% (1 per 20 or 1 per batch).
Stability checks of instrumentation are laboratory and instrument specific and
should be detailed in an SOP.
9.4.2 Matrix-Specific Parameters
The following table is a summary of parameters specific for the matrix.
Parameter,
matrix specific
Sample size, bulk
Paint chips
250 mga
Soil
1-2 9*
Dust
1 ft2 wipe"
Vacuumed
dust
300 mg*
Sample sizes are dependent on the digestive procedure, final volumes,
and instrumentation used for the analyses. These values are typical of
FLAA techniques.
39
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Other sample parameters, such as homogenization and digestion techniques,
are specific to a given matrix, instrument, and collection technique. Specifics of these
parameters should be detailed in an SOP.
40
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SECTION 10
DATA QUALITY AND REPORTS
This section discusses proficiency testing, rejection criteria, and reports and
record management.
10.1 PROFICIENCY TESTING
Laboratories must demonstrate proficiency in the Environmental Lead
Proficiency Analytical Testing (ELPAT) Program to be "recognized" by NLLAP (See
footnote on p. xi). Laboratories may participate in this program independently without
participating in an accreditation program.
10.1.1 Characteristics of Proficiency Testing Materials from ELPAT
10.1.1.1 Wipes—
Currently, the wipe proficiency testing (PT) material is a Whatman No. 40 filter
with added analyzed paint dust. This filter is manufactured to rigid quality standards
that provide a consistently low background level of Pb. However, in general, these
types of filters have poor durability and poor pickup efficiency and are, therefore, not a
suitable collection medium. ..Currently available "baby wipes," though not necessarily
of consistent quality for use as dust collectors, are more durable than the above-noted
filters, but have not been manufactured to provide a consistently low background level
of Pb. When a standardized, laboratory-grade wet wipe is developed for dust
collection, that material may be used as a "real world" testing medium.
10.1.1.2 Powdered Paint Chips—
The PT material is prepared from a composite of paint collected from the
outside of old buildings. The composite is then ground to a fine mesh and blended
with paint from different sources to achieve target concentrations.
10.1.1.3 Soil—
The PT material is prepared from a composite of soils taken from different
sources. The composite is then ground to a fine mesh and blended with soils from
difference sources to achieve target concentrations.
41
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(PT matrix materials, including ELPAT samples, are not to be used for
instrument calibration or primary standards. These materials have not been subjected
to rigorous characterization for their target concentrations.)
10.1.2 Target Concentrations for ELPAT Proficiency Testing Materials
Specifications and target concentrations of the NIOSH/AIHA PT samples are
shown below.
Wipes (Whatman No. 40 filters spiked with paint dust)*
• 20 u,g Pb/wipe
• 200 ug Pb/wipe
• 500 u.g Pb/wipe
• 5000 |xg Pb/wipe
Paint chips**
• 0.05% Pb
• 0.4% Pb
• 0.7% Pb
• 5.0% Pb
Soil*
• 20 mg Pb/kg (background levels in rural environments)
• 500 mg Pb/kg
• 1000 mg Pb/kg
• 5000 mg Pb/kg
It should be noted that PT materials and SRMs that are fine powders are
subject to significant stratifications from vibration in the laboratory. Therefore,
thorough mixing is essential prior to removing an aliquot for analysis.
There also are problems with paint dust and soil because of the non-uniformity
of the matrix. The PT program must assess the skills of the laboratory and not the
uniformity of the PT materials. Work continues on characterization of the uniformity of
the ELPAT PT materials to better characterize the material.
* The HUD Clearance Guideline recommendation is 200 fig Pb/sq ft on floors.
** CDC guidelines for paint chips are 500-1000 ppm (0.05-0.10%).
* ASTPHLD suggests that a soil Pb of less than 200 u.g/g (200 mg/kg) may not
result in the significant elevation of blood Pb in children, unless an unusually large
amount of soil is ingested.
42
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10.2 REJECTION CRITERIA AND CORRECTIVE ACTION
The following guidelines are recommended as minimum rejection criteria that
require corrective action prior to release of data. Data should be thoroughly
evaluated, even if one of these criterion is out of range, and corrective action taken
prior to release of data.
• Within day or intra-day variation of the calibration curve as measured by
continuing calibration verification is greater than 10%.
• Any blank that exceeds 20% of the regulatory limit or minimum limit of
concern.
• Spike recoveries of extractable Pb less than 75% or greater than 125% at
the mid-range concentration.
• Matrix-based quality control or check sample (also called control or laboratory
control sample) outside 80% to 120% of stated value.
• Unacceptable precision (> ±25% RPD) of duplicate samples (two aliquots of
the same bulk sample carried through the entire procedure.) Precision is
based on the concentration of the sample and the method detection limit.
Corrective actions include reanalysis of QC check samples. If these QC samples are
out of range, then repeat the entire analysis including recalibration and all QC
samples.
10.3 REPORTS AND RECORD MANAGEMENT
Reporting and record-keeping requirements are outlined in the HUD Interim
Guidelines (HUD, 1990).
"All information relating to field sample analysis and QA/QC sample analysis,
along with information on laboratory facilities, equipment, methods, and
procedures should be documented by the laboratory, so that an analytical event
can be recreated for an audit or investigation."
The HUD Interim Guidelines (HUD, 1990) recommend that the following general
categories of records should be kept.
• Cover page information including methods, dates, instruments, digestions,
and sign-offs by the laboratory director.
• Sample information including identification, blanks, QC samples, sample
weights, dilution factors, and batch identification.
• Results of initial precision and accuracy runs.
43
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• Results of calibration including sources of standards and detection limits.
• Results of blanks including type of blank and any corrections used.
• Results of calibration verification checks.
• Results of tests for accuracy and precision.
• Data reduction and reporting procedures including data calculations, outliers,
and data archiving.
More details are given in the HUD Interim Guidelines (HUD, 1990). The client
may have more specific needs, so the laboratory should be prepared to provide that
data.
There are no regulatory requirements for record retention for these matrices.
The HUD Interim Guidelines and NLLAP requirements suggest 10 years. Record
retention policies must be established with the client, with the realization that there
may be future regulatory requirements.
44
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SECTION 11
GENERAL RECOMMENDATIONS FOR AN ANALYSIS PROTOCOL
The analysis protocol for a digest may be specified in individual method
citations. Individual laboratory SOPs must provide specifics. The quality control
program should be based on the laboratory's continuous evaluation of its performance
(system process control). In the absence of laboratory-generated process controls,
the recommendations in Section 3.4 should be used regarding frequency of blanks,
calibration, and controls.
Since Pb is ubiquitous in the environment and in the laboratory, rigorous steps
must be specified in an SOP on how contamination control is to be achieved during
subsampling, digestion, and analysis. Cross-contamination should be documented by
monitoring of surfaces, glassware, and reagents. A protocol to reduce cross-
contamination from Pb is described by T. J. Murphy (Murphy, 1976).
The following are general recommendations for an analysis protocol:
• The instrument should be calibrated daily with an aqueous working standard
traceable to an aqueous-based SRM (SRM 3128).
• Stock working standards for Pb (10,000 ppm) are stable. However,
evaporation should be monitored by periodic weighing to document and
correct for evaporative losses. Sealed containers help control evaporation
loss; however, loss to container walls is possible.
• The daily calibration curve should consist of one initial calibration blank and
at least three standards covering the concentration range of the samples.*
• The 3-standard calibration curve should have a correlation coefficient of at
least 0.995.
• The calibration curve should be verified by the periodic use of continuing
calibration blank (CCB) and continuing calibration verification samples
throughout the run.
• The LCS (matrix-based and near the midpoint of the calibration curve) should
be ±20% of stated value.
* Calibration requirements are both instrument and method specific. SOPs for
specific analytical methods should be followed.
45
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One spiked matrix sample or duplicate matrix sample should be included per
batch of up to 20 samples. A suitable duplicate matrix sample would be split
digest samples because duplicate field samples cannot be collected.
Instrument drift should be documented and corrected using continuing
calibration verification (CCV) and continuing calibration blanks (CCB)
according to the method SOP.
Interference check samples (ICSs) for ICP-AES instrumentation (background
shifts and interelement interference) should be determined prior to performing
analyses to correct for potential interferences from components in the sample
matrix. The ability of the instrument to measure lead in the presence of
potential interference should be determined at the beginning, during the run,
and after the sample is run. Correction factors should be applied if available
on the specific ICP-AES instrument in use.
Background correction for GFAA using simultaneous methods (e.g., Zeeman,
Smith-Hieftje, Deuterium Arc) should be used at all times.
Matrix modifiers, used in GFAA, should be verified to be free of Pb
contamination.
Matrix-based SRMs at action levels, if available, should be used to verify
working standards and CRMs at monthly intervals.
All samples exceeding the upper limits of the calibration range should be
diluted to fit within the calibration range.
The SOP should provide for a means to control carryover following samples
with high concentrations (memory effect). Reruns of samples following a
high sample is recommended.
The SOP should provide for possible resampling of the submitted sample if
the result is at or above an "action level" to confirm a "positive" result.
Sample analysis priorities: Although the following scenario has been
suggested, consideration should also be given to development of an analysis
protocol using randomization of samples and blanks to minimize bias.
- Assemble all samples, standards, blanks, and background samples.
- Analyze those samples expected to contain Pb first.
- If a significant amount of Pb is found, analyze blanks and background
samples to determine if there is contamination.
- Blank collection media (wipes) should also be analyzed to determine the
background Pb levels.
46
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• QC data should be control charted in order to monitor trends and
QC excursions. The SOP must specify what is done in the event of
unacceptable trends or excursions.
Table 1 shows the recommended process quality control blanks and control
materials to be included in each batch. Table 2 shows the recommended instrumental
QC standards and their specifications.
47
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TABLE 1. QUALITY CONTROL SAMPLES AND PROCESS CONTROL
QC samples
Definition
Frequency
Method blanks
Spiked samples
Spiked sample
duplicates
Reference material
(standard reference)
Type 1 water—digest as a
sample with addition of all
reagents. Should reflect the
maximum treatment given any
one sample within the batch.
A portion of a sample is
fortified with all the target
analytes before preparation
and analyzed independently.
A portion of a same sample
used for the spiked sample is
fortified with all the target
analytes before preparation.
A material of known
composition, where anaiyte
levels are certified by the
manufacturer. These
materials should be traceable
to NIST standards.
1 per 20 samples, a
minimum of 1 per batch
1 per 20 samples per
matrix type, a minimum of
1 per batch
1 per 20 samples per
matrix type, a minimum of
1 per batch
1 per batch of samples
48
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50
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SECTION 12
SAFETY, HEALTH, AND HAZARDOUS WASTE
Laboratories must comply with OSHA Standard 29 CFR 1910.1450,
"Occupational Exposure to Hazardous Chemicals in Laboratories." This regulation
requires a Chemical Hygiene Plan that addresses all aspects of laboratory operations.
Certain Pb materials may be classified as hazardous waste. A solid waste
containing more than 200 ppm of Pb may fail the TCLP (Toxicity Characterization
Leaching Procedure) used to define a hazardous waste (U.S. EPA SW-846
Method 1310 for TCLP, followed by Methods 3050/6010). By failing the TCLP, a
waste is classified as hazardous and consequently requires special handling and
disposal. Therefore, steps must be detailed in an SOP for the handling of potentially
hazardous waste to include compliance with applicable local, state, and federal
regulations.
Digests, which are acidic in nature, also contain Pb and perhaps other metals.
These digests must be disposed of according to local state and federal regulations.
51
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SECTION 13
BIBLIOGRAPHY
Some of these references are available from the National Technical Information
Service (NTIS) at (703) 487-4650.
A2LA. Instrument Specific Check List: Atomic Absorption/Inductively Coupled
Plasma Spectrophotometry, 1992.
ACGIH. Industrial Ventilation, A Manual of Recommended Practices, 21st ed.,
American Conference of Governmental Industrial Hygienists, Cincinnati, OH, 1991.
APHA, AWWA, WPCF. Standard Methods for the Examination of Water and
Wastewater, 17th ed., 1989. Standard Method 3500-Pb B, Atomic Absorption;
Standard Method 3500-Pb C, Inductively Coupled Plasma Method.
ANSI/ASQC Q90-1987 (Equivalent to ISO 9000-1987). Quality Management and
Quality Assurance Standards: Guidelines for Selection and Use.
ANSI/ASQC Q91-1987 (Equivalent to ISO 9001-1987). Quality Systems: Model for
Quality Assurance in Design/Development, Production, Installation and Servicing.
ANSI/ASQC Q92-1987 (Equivalent to ISO 9002-1987). Quality Systems: Model for
Quality Assurance in Production and Installation.
ANSI/ASQC Q93-1987 (Equivalent to ISO 9003-1987). Quality Systems: Model for
Quality Assurance in Final Inspection and Test.
ANSI/ASQC Q94-1987 (Equivalent to ISO 9004-1987). Quality Management and
Quality System Elements: Guidelines.
ASTPHLD. Proceedings of the First National Conference on Laboratory Issues in
Childhood Lead Poisoning Prevention. Association of State and Territorial Public
Health Laboratory Directors Inc., Washington, DC, 1991.
CDC. Preventing Lead Poisoning in Young Children: A Statement by the Centers for
Disease Control, October 1991.
CRADA. Certificate of Analysis, Solid Waste Laboratory Reference Material: Paint
Sludge. Pb 753.0 ± 114.7 ppm.
53
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CRADA. Certificate of Analysis, Solid Waste Laboratory Reference Material: Paint
Blasting Waste. Pb 643.2 ± 129.4 ppm.
CRADA. Certificate of Analysis, Solid Waste Laboratory Reference Material: Bag
House Dust. Pb 1914.2 ± 410.6 ppm.
Epstein, M., B. I. Diamondstone, and T. E. Gills. A New River Sediment Standard
Reference Material. Talanta. 36:141-150, 1989.
HUD. Lead-Based Paint: Interim Guidelines for Hazard Identification and Abatement
in Public and Indian Housing. Appendix 5: Laboratory Testing for Lead (Pb) in Paint
Film, Dust, Air, and Soil, pp. A5-1 to A5-37, September 1990. (Appendix 13 includes
quality assurance information specific for Pb.)
HUD. NOFA for Lead-Based Paint (LBP) Risk Assessments. Federal Register.
June 29, 1992, pp. 28910-28943. [Contains Lead-Based Paint Risk Assessment
Protocol, which includes sampling protocols (Part III, pp. 28926-28927) for dust, paint
chips, and soil.]
ISO/IEC Guide 25 1990 (E). General Requirements for the Competence of Calibration
and Testing Laboratories. International Organization for Standardization/International
Electrotechnical Commission, Geneva, Switzerland, 1990.
JOAC. Guidelines for Collaborative Study Procedure to Validate Characteristics of a
Method of Analysis. J. Assoc. Off. Anal. Chem. International. 72:4, 1989.
Liabastre, A. A., K. A. Carlberg, and M. S. Miller. Quality Assurance for
Environmental Assessment Activities. In Methods of Environmental Data Analysis.
C. N. Hewitt, ed. Elsevier Applied Science, New York, 1992, pp. 259-299.
Murphy, T. J. The Role of the Analytical Blank in Accurate Trace Analysis. In
Accuracy in Trace Analysis. Vol. I, NBS Special Publication 422, 1976, pp. 509-539.
NIOSH. Manual of Analytical Methods, 3rded. DHHS (NIOSH) Publication 84-100,
1984.
NIST. Certificate of Analysis, SRM 1648 (Urban Particulate Matter), Pb 0.655 ± 0.008
(weight percent), November 16, 1978.
NIST. Certificate of Analysis, SRM 1579a (Powdered Lead-Based Paint), Pb 11.995 ±
0.031 (weight percent), February 3, 1992.
NIST. Certificate of Analysis, SRM 2579 (Lead Paint Film on Mylar Sheet, Set of 5),
3.53 mg/cm2 ± 0.24; 1.63 mg/cm2 ± 0.08; 1.02 mg/cm2 ± 0.04; 0.29 mg/cm2 ± 0.01;
< 0.0001 mg/cm2, July 7, 1992.
NIST. Certificate of Analysis, SRM 2704 (Buffalo River Sediment), Pb 161 ± 17 u.g/g,
July 9, 1990.
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NIST. Certificate of Analysis, SRM 2709 (Baseline Agricultural Soil), 18.9 fig/g ± 0.5,
October 16, 1992.
NIST. Certificate of Analysis, SRM 2710 (Highly Contaminated Soil), 5532 u.g/g ± 80,
October 16, 1992.
NIST. Certificate of Analysis, SRM 2711 (Moderately Contaminated Soil), 1162 u.g/g ±
31, October, 16, 1992.
Ratliff, T. A. Jr. The Laboratory Quality Assurance System: A Manual of Quality
Procedures with Related Forms. Van Norstrand Reinhold, New York, 1990.
Slavin, Walter. A Comparison of Atomic Spectroscopic Analytical Techniques.
Spectroscopy. 6(8): 16-21, October 1991.
Taylor, John K. Handbook for SRM Users. NBS (NIST) Special Publication 260-100,
September 1985.
U.S. EPA. Interim Guidelines and Specifications for Preparing Quality Assurance
Project Plans. QAMS-005/80 (Office of Monitoring Systems and Quality Assurance,
ORD/EPA), December 29, 1980.
U.S. EPA. Toxic Substances Control Act (TSCA); Good Laboratory Practice
Standards, Final Rule. Federal Register. Volume 54," Number 158, August 17, 1989,
pp. 34031 - 34050. [40 CFR Part 792]
U.S. EPA. Manual for the Certification of Laboratories Analyzing Drinking Water:
Criteria and Procedures for Quality Assurance, 3rd ed. EPA-570/9-90-008, April
1990a.
U.S. EPA. RCRA Quality Assurance Workshop: Outline of Mandatory and
Recommended QA Practices, Chapter One of SW-846, July 1990b.
U.S. EPA. Test Methods for Evaluating Solid Waste, Physical/Chemical Methods,
SW-846, 3rd ed., Revised, November 1990c.
U.S. EPA. Laboratory Accreditation Program Guidelines: Measurement of Lead In
Paint, Dust, and Soil. EPA-747/4-R-92-001, March 1992.
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APPENDIX
ACRONYMS AND GLOSSARY OF TERMS
ACRONYMS
AA
A2LA
ACIL
AIHA
ANSI
AOAC
APHA
ASTM
ASQC
ASTPHLD
AWWA
CCB
CCV
CERCLA
CDC
CMD
CNAEL
CRADA
CLP
CRM
EDL
ELLAC
ELPAT
EMPC
FLAA
GFAA
GLP
ICB
ICP-AES
ICP-MS
ICV
ICS
IDL
IMVL
ISO
LCS
Atomic Absorption
American Association for Laboratory Accreditation
American Council of Independent Laboratories
American Industrial Hygiene Association
American National Standards Institute
Association of Official Analytical Chemists
American Public Health Association
American Society for Testing and Materials
American Society for Quality Control
Association of State and Territorial Public Health Laboratory Directors
American Water Works Association
Continuing Calibration Blank
Continuing Calibration Verification
Comprehensive Environmental Responsibility, Compensation and Liability
Act
Centers for Disease Control
Chemical Management Division
Committee on National Accreditation of Environmental Laboratories
Cooperative Research and Development Agreement
Contract Laboratory Program
Certified Reference Material
Estimated Detection Limit
Environmental Lead Laboratory Accreditation Committee (AIHA)
Environmental Lead Proficiency Analytical Testing (AIHA/NIOSH)
Estimated Maximum (Protocol) Concentration
Direct Flame Aspiration Atomic Absorption Spectrometry
Graphite Furnace Atomic Absorption Spectrometry
Good Laboratory Practices Standards (TSCA)
Initial Calibration Blank
Inductively Coupled Plasma Emission Spectrometry
Inductively Coupled Plasma-Mass Spectrometry
Initial Calibration Verification
Interference Check Standard
Instrument Detection Limit
Interlabpratory Method Validation Study
International Organization for Standardization
Laboratory Control Sample
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LOQ Limit of Quantitation
LSA Laboratory Systems Audit
MCL Maximum Contaminant Level
MDL Method Detection Limit
MOU Memorandum of Understanding
MRI Midwest Research Institute
NATA National Association of Testing Authorities (Australia)
NIOSH National Institute for Occupational Safety and Health
NIST National Institute of Standards and Technology
NLLAP National Lead Laboratory Accreditation Program
NTIS National Technical Information Service
NVLAP National Voluntary Laboratory Accreditation Program
OSW Office of Solid Waste (U.S. EPA)
PE Performance Evaluation
PM Preventive Maintenance
PT Proficiency Testing
POL Practical Quantitation Limit
QA Quality Assurance
QAMS Quality Assurance Management Staff
QAPjP Quality Assurance Project Plan
QAPP Quality Assurance Program Plan
QC Quality Control
QM Quality Manual
RCRA Resource Conservation and Recovery Act
RE Relative Error
RPD Relative Percent Difference
SAP Sample Analysis Plan
SARA Superfund Amendments and Re-authorizations Act of 1986
SOP Standard Operating Procedure
SRM Standard Reference Material Produced by NIST
TCLP Toxicrty Characteristic Leaching Procedure
TPB Technical Programs Branch
TQM Total Quality Management
TSCA Toxic Substances Control Act
XRF X-Ray Fluorescence
WAL Work Assignment Leader (L K. Lowry)
WAM Work Assignment Manager (J. Scalera)
WPCF Water Pollution Control Federation
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GLOSSARY
Accreditation:
Accredited laboratory:
Acceptance limits:
Accuracy:
Aliquot:
Analytical blank:
Bias:
Blind sample:
Calibrate:
Calibration blank:
Calibration-check:
A formal recognition that an organization (e.g., laboratory)
is competent to carry out specific tasks or specific types of
tests. See also Certification.
A laboratory that has been evaluated and given approval to
perform a specified measurement or task, usually for a
specific property or analyte and for a specified period of
time.
Data quality limits specified by the National Lead Laboratory
Accreditation Program for analytical method performance.
The degree of agreement between an observed value and
an accepted reference value. Accuracy includes a
combination of random error (precision) and systematic
error (bias) components which are due to sampling and
analytical operations; a data quality indicator. See
Precision and Bias.
See Subsample
See Digestion blank.
The systematic error manifested as a consistent positive or
negative deviation from the known true value.
A.subsample submitted for analysis with a composition and
identity known to the submitter but unknown to the analyst
and used to test the analyst's or laboratory's proficiency in
the execution of the measurement process.
To determine, by measurement or comparison with a
standard, the correct value of each scale reading on a
meter or other device, or the correct value for each setting
of a control knob. The levels of the calibration standards
should bracket the range of planned measurements. See
Calibration curve.
See Initial calibration blank.
See Calibration verification.
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Calibration-check
standard:
Calibration curve:
Calibration drift:
Calibration standard:
Calibration solution:
See Calibration verification.
The graphical relationship between the known values for a
series of calibration standards and instrument responses.
The difference between the instrument response and a
reference value after a period of operation without
recalibration. See Continuing calibration verification.
A substance or reference material used to calibrate an
instrument.
See Calibration standard.
Calibration verification: See Initial or continuing calibration verification.
Certification:
Certified Reference
Material (CRM):
Chain of custody:
The process of testing and evaluation against specifications
designed to document, verify, and recognize the
competence of a person, organization, or other entity to
perform a function or service usually for a specified time.
See also Accreditation.
A reference material that has one or more of its property
values established by a technically valid procedure and is
accompanied by or traceable to a certificate or other
documentation issued by a certifying body. See
Certification and Reference material.
An unbroken trail of accountability that insures the physical
security of samples, data, and records.
Check sample:
An uncontaminated sample matrix spiked with known
amounts of analytes, usually from the same source as the
calibration standards, it is generally used to establish the
stability of the analytical system, but may also be used to
assess the performance of all or a portion of the
measurement system. See also Quality control sample.
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Continuing Calibration
Blank (CCB)
Continuing Calibration
Verification (CCV)
Control chart:
Control sample:
Corrective action:
Deficiency:
Digestion blank:
Duplicate analyses or
measurements:
A standard solution which has no analyte and is used to
verify blank response and freedom from carryover. The
CCB should be analyzed after the CCV and after the
Interference Check Standard (ICS).
A standard solution (or set of solutions) used to verify
freedom of excessive instrumental drift. The concentration
to be near mid-range of linear curve. The CCV should be
matrix matched to acid content present in sample
digestates. The CCV should be analyzed before and after
all sample digests and periodically throughout the analyses
of sample digests.
A graph of some measurement plotted over time or
sequence of sampling, together with control limit(s) and,
usually, a central line and warning limit(s).
See Laboratory control sample.
Action taken to correct a deficiency noted in a technical
systems audit. See Deficiency and Technical systems
audit.
A failure to fully comply with the requirements of the NLLAP
program usually noted during a technical systems audit.
See NLLAP and Technical systems audit.
A mixture of all reagents used for the digestion of paint,
soil, or dust matrices but without the matrix. This blank, is
carried through all steps of the analysis starting with the
digestion step. This blank evaluates the process for
contamination from the laboratory.
The analyses or measurements of the variable of interest
performed identically on two subsamples of the same
sample. The results from duplicate analyses are used to
evaluate analytical or measurement precision but not the
precision of sampling, preservation, or storage internal to
the laboratory.
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Duplicate samples:
External quality control:
Field blank:
Initial calibration
blank (ICB):
Initial calibration
verification (ICV):
Instrument maintenance
log:
Interference check
standard (ICS):
Two samples taken from and representative of the same
population and carried through all steps of the sampling anc
analytical procedures in an identical manner. Duplicate
samples are used to assess variance of the total method
including sampling and analysis.
Activities that are routinely initiated and performed by
persons outside of normal operations to assess the
capability and performance of a measurement process.
A clean sample of matrix (e.g., paint, soil, dust, wipe)
carried to the sampling site, exposed to the sampling
conditions (e.g., bottle caps removed), returned to the
laboratory, treated as an environmental sample, and carried
through all steps of the analysis. For example, clean quartz
sand, non-Pb containing paint, or a clean wipe could be
used as a field blank. The field blank, which should be
treated just like the sample, evaluates possible site
contamination sources such as airborne contaminants.
A standard solution that contains no analyte and is used for
initial calibration and zeroing instrument response. The ICB
must be matrix matched to acid content present in sample
digestates. The ICB should be measured during calibration
and after calibration.
A standard solution (or set of solutions) used to verify
calibration standard levels. Concentration of analyte to be
n&ar mid-range of linear curve which is made from a stock
solution having a different manufacturer or manufacturer lot
identification than the calibration standards. The ICV must
be matrix matched to acid content present in sample
digestates. The ICV should be measured after calibration
and before measuring any sample digestates.
A chronological record of preventive and emergency
maintenance performed on an analytical instrument. The
logs include record of calls, service technician summaries,
records of calibration etc.
A standard solution (or set of solutions) used for ICP-AES
to verify accurate analyte response in the presence of
possible spectral interferences from other analytes present
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in samples. The concentration of analyte to be less than
25% of the highest calibration standard, concentration of
interferant will be 200 u.g/MI of Al, Ca, Fe, and Mg. The
ICS must be matrix matched to acid content present in
sample digestates.
Internal quality control: See Intralaboratorv quality control.
Internal standard: A standard added to a test portion of a sample in a known
amount and carried through the entire demonstration
procedure as a reference for calibration and controlling the
precision and bias of the applied analytical method.
Intralaboratory precision: A measure of the method/sample specific analytical
variation within a laboratory, usually given as the standard
deviation estimated from the results of duplicate/replicate
analyses.
Intralaboratory quality
control:
Laboratory blank:
Laboratory control
sample (LCS):
Laboratory systems
audit:
The routine activities and checks, such as periodic
calibrations, duplicate analyses, and spiked samples, that
are included in normal internal procedures to control the
accuracy and precision of measurements.
See Digestion blank.
A matrix-based reference material with an established
concentration obtained from a source independent of the
instrument calibration and traceable to NI5T or other
reference materials. The LCS is carried through the entire
procedure from digestion through analysis as a field
sample. The purpose of the LCS is to evaluate bias of the
method.
See Technical systems audit.
Matrix blank:
Method blank:
A sample of the matrix (paint chips, soil, dust) but without
the analyte (Pb). This sample goes through the complete
analysis including digestion.
See Digestion blank.
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Method performance:
Method detection limit
(MDL):
Mobile laboratory:
NLLAP requirements:
Precision:
Primary standard:
Proficiency testing:
Quality assurance (QA):
Quality assurance
program:
Quality assurance
coordinator:
A general term used to document the characteristics of a
method. These characteristics usually include method
detection limits, linearity, precision, accuracy and bias.
The minimum concentration of an analyte that, in a given
matrix and with a specific method, has a 99% probability of
being identified, qualitatively or quantitatively measured,
and reported to be greater than zero.
A mobile laboratory is a self-contained, mobile facility that
moves under its own power or is conveyed on a trailer, and
does not remain at a site for more than two years.
Requirements specified by the EPA National Lead
Laboratory Accreditation Program (NLLAP) in order to be
accredited for lead analysis in paint, soil and dust matrices
by an EPA-recognized laboratory accreditation organization.
The degree to which a set of observations or
measurements of the same property, usually obtained
under similar conditions, conform to themselves; a data
quality indicator. Precision is usually expressed as
standard deviation, variance, or range, in either absolute or
relative terms.
A substance or device with a property or value that is
unquestionably accepted (within specified limits) in
establishing the value of the same or related property of
another substance or device.
A systematic program in which one or more standardized
samples is analyzed by one or more laboratories to
determine the capability of each participant.
An integrated system of activities involving planning, quality
control, quality assessment, reporting, and quality
improvement to ensure that a product or service meets
defined standards of quality within a stated level of
confidence.
See Quality assurance.
See Quality manager.
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Quality control (QC):
Quality manager:
Reagent blank:
Reference material:
Reference standard:
Relative percent
difference:
The overall system of technical activities whose purpose is
to measure and control the quality of a product or service
so that it meets the needs of users. The aim is to provide
quality that is satisfactory, adequate, dependable, and
economical.
The manager of the quality system. The Quality Manager
is independent of the analyst and reports directly to
management.
See Digestion blank.
A material or substance, one or more properties of which
are sufficiently well established to be used for the
calibration of an apparatus, the assessment of a
measurement method, or assigning values to materials.
See Calibration standard.
A term defined as
I R - R I
RDP = 1 2' x100
where I R, -_R21 represents the absolute difference in two
values and R represents the average of two values.
Replicate analysis
or measurements:
Replicate sample:
The analysis or measurement of the variable of interest
performed identically on two or more subsamples of the
same sample within a short time interval. See Duplicate
analysis or measurement.
Two or more samples representing the same population
characteristic, time, and place, which are independently
carried through all steps of the sampling and measurement
process in an identical manner. Replicate samples are
used to assess total (sampling and analysis) method
variance. Often incorrectly used in place of the term
"replicate analysis." See Duplicate samples and Replicate
analysis.
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Report sign-off:
Reproducibility:
Rinseate blank:
Sample log:
Sample tracking:
Secondary standard:
Site blank:
Site visit:
Site visitor:
Spiked matrix:
Spiked reagent blank:
The Technical Manager or designee authorized to review
and sign analysis reports.
The extent to which a method, test or experiment yields the
same or similar results when performed on subsamples of
the same sample by different analysts or laboratories.
A sample of a "used" cleaning fluid rinse solution, also
called an equipment blank. Rinseate blank examples
include a final rinse of the device used to collect soil or
vacuumed dust or to clean the scoop used to collect soil or
vacuumed dust. The rinseate blank is used in rinsing
collection media and equipment prior to use to monitor
possible cross contamination. The rinseate blank goes
through the complete analysis, including the digestion.
The document where sample identification, condition, etc is
noted when samples arrive at the laboratory. The log is
part of the sample tracking system. See Sample tracking.
A system of following a sample from receipt at the
laboratory, through sample processing and analysis, and to
final reporting. The system includes unique numbering or
bar coding labels and the use of a sample log.
A standard whose value is based upon comparison with a
primary standard.
See Field blank.
An on-site visit to a laboratory for the purpose of conducting
a technical systems audit.
A person who conducts technical system audits. The terms
site visitor, auditor and assessor are often used
interchangeably. See Technical systems audit.
See Spiked sample.
A specified amount of reagent blank fortified with a known
mass of the target analyte, usually used to determine the
recovery efficiency of the method.
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Spiked sample:
Split samples:
Standard addition:
Standard operating
procedure (SOP):
Standard reference
material (SRM):
Standardization:
Stock solution:
Stratification:
Subsample:
A sample prepared by adding a known mass of target
analyte to a specified amount of matrix sample for which an
independent estimate of target analyte concentration is
available. Spiked samples are used, for example, to
determine the effect of the matrix on a method's recovery
efficiency.
Two or more representative portions taken from a sample
or subsample and analyzed by different analysts or
laboratories. Split samples are used to replicate the
measurement of the variable(s) of interest.
The procedure of adding known increments of the analyte
of interest to a sample to cause increases in detection
response. The level of the analyte of interest present in the
original sample is subsequently established by extrapolation
of the plotted responses.
A written document that details the method of an operation,
analysis, or action whose techniques and procedures are
thoroughly prescribed and which is accepted as the method
for performing certain routine or repetitive tasks.
A certified reference material produced by the U.S. National
Institute of Standards and Technology and characterized for
absolute content independent of analytical method.
The process of establishing the quantitative relationship
between a known mass of target material (e.g.,
concentration) and the response variable (e.g., the
measurement system or instrument response). See
Calibrate and Calibration curve.
A concentrated solution of analyte(s) or reagent(s) prepared
and verified by prescribed procedure(s), and used for
preparing working standards or standard solutions.
The division of a target population into subsets or strata
which are internally more homogeneous with respect to the
characteristic to be studied than the population as a whole.
A representative portion of a sample. A subsample may be
taken from any laboratory or a field sample.
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Substrate:
Systems audit:
Technical systems
audit:
Trip blank:
Validation:
Working standard:
This term has a very specialized use in the Pb-abatement
area. It refers specifically to the material to which paint is
attached, such as wallboard, concrete, wood, steel, etc.
See Technical systems audit.
A thorough systematic on-site, qualitative review of
facilities, equipment, personnel, training, procedures, record
keeping, data validation, data management, and reporting
aspects of a total measurement system.
A clean sample, including collection media, that is carried to
the sampling site and transported back to the laboratory for
analysis without being opened. This blank is analyzed as
a regular sample through all steps. The trip blank
evaluates the integrity of the sample container.
The process of substantiating specified performance
criteria.
See Secondary standard.
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