EPA-6QO/1-77-020
April 1977
Environmental Health Effects Research Series
RECOMMENDATIONS OF THE EPA/NBS
WORKSHOP ON THE NATIONAL
ENVIRONMENTAL SPECIMEN
BANK
Health Effects Research Laboratory
Office of Research and Development
U.S. Environmental Protection Agency
Research Triangle Park, North Carolina 27711
-------
RESEARCH REPORTING SERIES
Research reports of the Office of Research and Development, U.S. Environmental
Protection Agency, have been grouped into nine series. These nine broad cate-
gories were established to facilitate further development and application of en-
vironmental technology. Elimination of traditional grouping was consciously
planned to foster technology transfer and a maximum interface in related fields.
The nine series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
4. Environmental Monitoring
5. Socioeconomic Environmental Studies
6. Scientific and Technical Assessment Reports (STAR)
7. Interagency Energy-Environment Research and Development
8. "Special" Reports
9. Miscellaneous Reports
This report has been assigned to the ENVIRONMENTAL HEALTH EFFECTS RE-
SEARCH series. This series describes projects and studies relating to the toler-
ances of man for unhealthful substances or conditions. This work is generally
assessed from a medical viewpoint, including physiological or psychological
studies. In addition to toxicology and other medical specialities, study areas in-
clude biomedical instrumentation and health research techniques utilizing ani-
mals — but always with intended application to human health measures.
This document is available to the public through the National Technical Informa-
tion Service, Springfield, Virginia 22161.
-------
EPA-600/1-77-020
April 1977
RECOMMENDATIONS OF THE EPA/NBS WORKSHOP ON
NATIONAL ENVIRONMENTAL SPECIMEN BANK
by
Harry L. Rook
Analytical Chemistry Division
National Bureau of Standards
Washington, D.C. 20234
and
George M. Goldstein
Health Effects Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, N.C. 27711
INTERAGENCY AGREEMENT NO. IAG-D4-0568
Project Officer
George M. Goldstein
Clinical Studies Division
Health Effects Research Laboratory
Research Triangle Park, N.C. 27711
HEALTH EFFECTS RESEARCH LABORATORY
OFFICE OF RESEARCH AND DEVELOPMENT
U.S. ENVIRONMENTAL PROTECTION AGENCY
RESEARCH TRIANGLE PARK, N.C. 27711
-------
DISCLAIMER
This report has been reviewed by t^he Health Effects Research
Laboratory, U.S. Environmental Protection Agency, and approved for
publication. Approval does not signify that the contents necessarily
reflect the views and policies of the U.S. Environmental Protection
Agency, nor does mention of trade names or commercial products
constitute endorsement or recommendation for use.
11
-------
FOREWORD
The many benefits of our modern, developing, industrial society are
accompanied by certain hazards. Careful assessment of the relative risk
of existing and new man-made environmental hazards is necessary for the
establishment of sound regulatory policy. These regulations serve to
enhance the quality of our environment in order to promote the public
health and welfare and the productive capacity of our Nation's population.
The Health Effects Research Laboratory, Research Triangle Park,
conducts a coordinated environmental health research program in toxicology,
epidemiology, and clinical studies using human volunteer subjects. These
studies address problems in air pollution, non-ionizing radiation,
environmental carcinogenesis and the toxicology of pesticides as well as
other chemical pollutants. The Laboratory develops and revises air quality
criteria documents on pollutants for which national ambient air quality
standards exist or are proposed, provides the data for registration of new
pesticides or proposed suspension of those already in use, conducts research
on hazardous and toxic materials, and is preparing the health basis for
non-ionizing radiation standards. Direct support to the regulatory function
of the Agency is provided in the form of expert testimony and preparation of
affidavits as well as expert advice to the Administrator to assure the
adequacy of health care and surveillance of persons having suffered imminent
and substantial endangerment of their health.
As part of the Health Effects Research Laboratory's efforts to provide
a coordinated environmental health research program, the U.S. Environmental
Protection Agency and the National Bureau of Standards co-sponsored a
Workshop to review current technical developments and to make recommendations
affecting the proposed National Environmental Specimen Bank (NESB). The NESB
is part of an International effort to monitor the environment for hazardous
substances. The advantages of such a program will permit the Agency to
assess the effectiveness of its present environmental control techniques
by monitoring pollutant trends, as well as establishing environmental
baseline levels of new pollutants or pollutants of current concern not
previously investigated.
iJohn H. Knelson, M.D.
Director,
Health Effects Research Laboratory
iii
-------
ABSTRACT
On August 19 and 20th, 1976, the National Bureau of Standards and the
U.S. Environmental Protection Agency co-sponsored a Workshop to review
technical developments and to make recommendations on implimentation of the
National Environmental Specimen Bank. The Workshop consisted of a review
session where past considerations were discussed; a technical session where
recent analytical research relevant to the sample bank was abstracted and
discussed; and a planning session where planning and design of a prototype
banking system was outlined.
This report is a summary of the presentations, discussion, and con-
clusions of the Workshop attendees. The attendees represented a wide cross
section of interested Federal and Non-Federal research groups as well as
International representation including the International Tissue Banking
Program (Sponsored by the World Health Organization, The Commission of
European Communities and the U.S. Environmental Protection Agency) and the
Federal Republic of Germany-.
The workshop concluded that with the ever increasing influx of new
man-made substances into our ecosystem, that a formalized, systematic
approach is needed to assess the environmental impact of these substances on
a national as well as an international level. The technology to initiate
a pilot banking program is presently available and was formulated into a
five-year pilot bank program. This program will be evaluated at each stage
of development.
This report was submitted in partial fulfillment of EPA Interagency
Agreement IAG-D4-0568 by the National Bureau of Standards under the partial
sponsorship of the U.S. Environmental Protection Agency. This report covers
the period August 19 and 20, 1976, and the work was completed as of
January 31, 1977.
iv
-------
TABLE OF CONTENTS
Foreword iii
Abstract iv
Figures vi
Acknowledgment vii
1. Introduction 1
2. Background and History 3
3. Results of Current Research Programs 7
4. Discussions and Recommendations 10
5. Conclusions 14
Bibliography 18
Apendices 19
A. The Cleaning, Analysis and Selection of Containers for
Trace Element Samples 19
B. Evaluation by Activation Analysis of Elemental Retention
in Biological Samples after Low Temperature Ashing .... 33
C. Determination of Chromium in Biological Matrices by
Neutron Activation: Application to Standard Reference
Materials 44
-------
FIGURES
Number Page
1 National Environmental Specimen Bank (NESB) Concepts 13
2 Pilot Bank samples 14
3 NESB Pilot Bank 15
VI
-------
ACKNOWLEDGEMENTS
The U.S. Environmental Protection Agency and the National Bureau of
Standards wish to acknowledge their appreciation to all the participants
of the National Environmental Specimen Bank Workshop; Progress and
Planning. Without their involvement and guidance at this most crucial
time in the development of the National Environmental Specimen Bank,
this proposed Pilot Bank Plan would never have emerged. We especially
want to thank Dr. Arthur Wolff, representing the International Bank
Conference Sponsored by the Commission of European Communities, The
World Health Organization, and the U.S. Environmental Protection Agency;
and Dr. F. Schmidt-Bleek of the Umweltbundesamt, Federal Republic of Germany,
for representing the International Communities in this most vital
program of world-wide concern.
VII
-------
SECTION 1
INTRODUCTION
On August 19 and 20th, the National Bureau of Standards (NBS) and the
Environmental Protection Agency (EPA) co-sponsored a Workshop to review
current technical developments and to make recommendations affecting the
proposed National Environmental Specimen Bank (NESB). The attendees
represented a wide cross section of interested Federal and non-Federal
research groups as well as representatives from The Federal Republic of
Germany and the International Tissue Banking Program, sponsored by the World
Health Organization (WHO), U.S. E.P.A., and Commission of European
Communities (CEC).
The Workshop was conducted as an essential part of the program plan-
ning, preliminary to the establishment of the National Environmental
Specimen Bank. There has been a concerted effort on the part of EPA and
NBS to initiate the NESB system. This system will provide a dual output
useful to many environmental monitoring and assessment programs; that of
credable real time monitoring data for an environmental early warning
system and that of providing well preserved and documented environmental
samples for future retrospective analysis.
The Workshop was divided into three half-day sessions. The first
session was a review of the rationale and objectives of the NESB system.
The second session was a review of scientific research pertinent to NESB
objectives. The final day was devoted to a planning and design of a
prototype system for the banking and analysis of environmental samples.
During this planning session, the following considerations were specifically
addressed:
1. A review of the issues that created the need for the
National Environmental Specimen Bank with specific emphasis on
current environmental problems which would be aided by the
existence of a sample banking system.
2. The development of specific objectives, identifying the functions
that the bank would perform, and how it would meet the needs as
specified in the rationale statement.
3. Identify the types of specimens that would be stored in the bank,
including demographic and technological data, based upon existing
and anticipated future needs and objectives.
-------
4. Identify and evaluate the potential users of the bank and set
forth guidelines to govern those who could use the bank and what
could be drawn from it.
5. Determine if the technology is presently available to initiate a
pilot program.
With the successful completion of these tasks, a plan was generated
for the establishment of a pilot bank program. This pilot bank will utilize
scaled-up laboratory procedures established at NBS as part of the NBS/EPA
cooperative effort to provide standardized sampling, storage and analytical
protocols for environmental samples, and identify additional areas of
research and development that would be needed before the full National
Environmental Specimen Bank is formalized.
-------
SECTION 2
BACKGROUND AND HISTORY
The storage of human tissues and other environmental samples for
analytical measurements is a natural outgrowth of the EPA environmental
monitoring system. The need for environmental monitoring is well estab-
lished and is currently a major EPA responsibility. A comprehensive
monitoring system is an integral part of the EPA mandate to assess the
total environmental impact of pollutants that may lead to deleterious
effects on human health.
The health research objectives of EPA can be stated as:
1. To minimize adverse human effects
- Prevent exposure to harmful new agents
- Reduce exposure to existing agents
- Predict relative effects of control options
2. To quantitate the benefits of environmental control.
3. To optimize the environment for man's health and well-being.
A preliminary program using human tissue samples as monitors for trace
element pollutant burdens was initiated in the EPA human pollutant burden
studies program.
From the very onset of the human pollutant burden studies, short-term
tissue banking became an integral part of this program. Human tissues were
viewed as environmental dose integrators of multiple proportions. The
integration of a pollutant level with time was used to estimate pollutant
trends. Analyses of these pollutant trends served as a resource for
standards setting, inputs for cost-benefit assessments of pollution abate-
ment measures, and guides for determining research priorities.
The problem orientated approach of the early pollutant burden studies
did not fully utilize the capabilities of a tissue banking program. At
that time, a tissue or group of tissues was collected to test a specific
hypothesis. These tissues were stored until they could be analyzed, and
were then discarded. As the pollutant burden program expanded, the need
for a fully developed tissue banking system became apparent.
-------
This banking system was envisioned as having a dual function.
First, representative portions of samples included in the bank would be
analyzed at the time of introduction to provide real time monitoring and
evaluation of pollutant trends. Evaluation of these trends would serve
as early warning sentinels so that proper control measures could be taken
to halt rising human body burdens before irreversible damage could occur.
Second, a specimen bank would enable the analyst to use tomorrow's
mere sensitive and specific methods of chemical analysis on today's
samples. The improved measurement methodology would enable health scientists
to determine accurate levels for substances that would be -either undetectable
or poorly analyzed by today's less sensitive methodology. The existence
of a specimen bank would provide the opportunity to determine what the
body burden of newly recognized toxic substances was in the past and to
determine if their levels had changed with time.
In EPA's continuing effort to establish a National Environmental
Specimen Bank, a two day working session was held in February 1973 at
EPA's National Environmental Research Center, Research Triangle Park,
North Carolina to discuss and propose plans for the establishment of a
National Environmental Specimen Bank System.
The broad objectives of this working session were:
1. Establish current trends in human pollutant burdens (short-
term banking).
2. Creating a specimen bank that would provide retrospective
analytical capability (long-term banking).
One major recommendation from the working session was that a sample
banking system should be established at the national level that would
cross agency lines and provide human tissues representative of that
period in time from which the sample was taken. The proper storage of
these tissues would permit retrospective analysis using improved methodologies
that -.yere likely to be available.
In 1972, the National Academy of Sciences/National Research Council
(NAS/NRC) addressed tissue banking when they stressed the lack of coor-
dination in the numerous programs by components of Federal and State
governments, private industry and academic institutions to collect, store
and analyze specimens of environmental interest.
In an effort to upgrade the availability and long-term protection of
environmental samples and to make the information gathered with each
collection readily available, the Subcommittee on the Geochemical Environ-
ment in relation to Health and Disease of the National Committee for
Geochemistry, National Academy of Sciences/National Research Council at
their Asilomar Workshop in California (1972) recommended that a group of
specialists be convened to study this problem at its Capon Springs Workshop
in May 1973.
-------
The Capon Springs Workshop concluded that the U.S. Government should
establish, on a permanent basis, a National Environmental Specimen Bank.
Initial coordinating and funding of the multi agency system should be
considered by the National Science Foundation (NSF). The Environmental
Protection Agency should be considered as the most logical organization to
establish the system.
Four tasks were proposed to begin development of the NESB.
Task I. Conduct an inventory and assess the value of existing
specimen collections as potential candidates for participation in the NESB.
Task II. Establish a steering committee composed of representatives
from a variety of concerned groups that are providing funds, participating
in specimen collection, and operating monitoring programs. This committee
would be responsible for:
1. Developing the organizational and managerial structure
of the NESB.
2. Identify the types of specimens and information to be stored
in the Banking System.
3. Develop interim protocols for sampling, sample handling, and
storage of specimens to be included in the bank.
A. Plan for a data handling, storage, and retrieval system.
Task III. Identify research needs as determined during the imple-
mentation of the NESB. Areas already identified are:
1. Sampling strategies
2. Sample processing and storage procedures
3. Measurement strategy
Task IV. Conduct meetings at the national and international level, of
user and research groups, to exchange current information that would be
relevant to the NESB.
During this time, the rapid growth of EPA's human pollutant burden
program dictated the need for a sophisticated system of standardized
protocols for sample collection, preparation, storage and analysis.
In December, 1973, this need was addressed by the EPA and the NSF in
a meeting to formulate plans for the development of a National Environmental
Specimen Bank. At this meeting, a four point proposal was generated, with
joint funding being provided by NSF, EPA and NBS. This proposal was designed
to set the ground work for establishing a specimen bank; a bank that would
meet the requirements of both Federal and State regulatory agencies and
that of the academic community.
-------
The four point proposal contained the following elements:
1. A survey of existing specimen collections
2. An evaluation of existing specimen collections
3. Research and development of sampling, storage, and analysis
protocols
4. The development of a planning document for the organization and
management of the NESB
The specimen collection survey, conducted nationally, was used to
generate a broad data base on various aspects of specimen banking. This
survey was conducted by the Oak Ridge National Laboratory.
NBS then had the responsibility of critically evaluating the survey
results to determine their utility and applicability to the National
Environmental Specimen Bank program.
In general, the survey evaluation revealed that the collections,
sampled and stored for purposes other than retrospective analysis, provided
little information that was applicable to the analytical nature of the
specimen bank program. Their use, however, was primarily in the area of
taxonomy (1).
Concurrent with the survey, NBS began and is continuing research to
generate state-of-the-art methodology for sample collection, preparation,
storage and analysis. This task is envisioned as a continuing function
for the life of the bank. This approach would allow for a continued
updating of methodology to meet the needs of the bank.
Finally, the last task was the formulation of a plan for the development
and operation of the bank. The clarification of this plan with respect
to several key issues was to be the final result of the present Workshop.
Relevant scientific issues which were discussed were:
1. Review issues and need for the bank
2. Development of specific bank objectives
3. Identify and specify sample types
4. Specimen collection, preparation and storage requirements
5. Evaluate and formulate methods of analysis
-------
SECTION 3
RESULTS OF CURRENT RESEARCH PROGRAMS
Since January 1975, the Analytical Chemistry Division of the National
Bureau of Standards has conducted a continuing research program to improve
methodologies for the collection, storage, and analysis of NESB samples.
The program currently underway is pursuing three avenues of inves-
tigation. The first is a complete survey of available literature con-
cerning problems of sampling, transporting, and storage of biological and
environmental samples for analytical purposes. The second is an active
research program to improve methodologies for sampling, sample handling,
and storage of the above matrices. The third area concerns the evaluation
and improvement of analytical techniques to be used for the analysis of the
trace constituents of interest. The latter two portions of the NBS research
program are currently directed primarily towards trace elements, but future
research will be directed toward other substances of interest, such as
trace organic species.
Literature Survey
The survey of recent literature entailed the use of both manual search-
ing and computer assisted bibliographical retrieval services. These included
Medline, Chemcon, Biosis, Cain, Defense Documentation Center, and others.
The specific components of interest that were researched included trace
elements, pesticides, other trace organics, radionuclides, and microbiologi-
cal species. This survey, containing over 200 references, represents a
single base of scientific data for the development of guidelines for
sampling techniques, container cleaning methods and storage techniques (2).
In general, the information found in the literature survey was limited,
often contradictory, and usually pointed out problems rather than solutions.
Several useful points of information that were documented include references
on trace element contamination of biological tissues due to stainless steel
sampling implements, and the substantial problems associated with currently
accepted water sampling and storage techniques.
Sampling and Storage
A major portion of the current NBS research program has been the
experimental evaluation of contamination and losses of the trace constituents
of interest during sampling, sample handling, and long-term storage. One
of the initial projects in this program was the evaluation of twelve
-------
polymeric materials for their trace element content, and for the possibility
of removing these trace elements when contacted by liquid samples. This
study was made using three complimentary trace analytical techniques,
neutron activation analysis, atomic absorption, and spark source mass
:;pectrometry. The utilization of a multidisciplinary analyical approach
gave an almost complete coverage of trace elements of interest.
The results of this study indicated that many materials were grossly
contaminated by trace elements from plasticizers, formulators, and other
process materials. However, conventional polyethylene and Teflon were
found to be reasonably clean and it was generally found that less than 10
percent of the bulk trace element content could be leached out, even with
conditions as severe as a 2-hour hot leach with 6N acid. The complete
details of this study are included in Appendix A.
A second, and equally important part of the current research program
has been a study and evaluation of long-term storage techniques which would
be adequate for tissue and other biologically active samples. The effects
of microbiological action on trace constituent concentrations and distributions
are well documented. However, the mechanism for complete long-term elimin-
ation of that micro-biological activity is not well documented. Freezing
has long been applied as a technique for analytical storage, however no
study has yet been performed to document the reliability of this method of
storage for more than a short period of time.
* M
More recent studies into lyophilization have demonstrated minimal
losses and/or contamination of trace elements during the sample processing.
The NBS has now documented the viability of the freeze-drying technique to
stabilize trace element composition. Standard Reference Material Bovine
Liver (SRM 1577) has been shown to be unchanged for more than five years.
The bulk material for this SRM was freeze-dried, ground, blended, and
bottled. This material was analyzed and certified for trace element composition
in 1°72. To the present time, no documented evidence of trace element loss
or alteration has occurred. The results of a complete study of losses on
freeze-drying of liquid samples were published in Analytical Chemistry (3).
Finally, the technique of low temperature ashing (LTA) has been
evaluated for long-term storage and found to have many advantages. A
recent study at NBS investigated the loss of trace elements during plasma
ashing using both radioactive tracers, and activation analysis of samples
before and after ashing. The results obtained indicate that over thirty
(30) trace elements are retained quantitatively during LTA. Five elements,
mercury, osmium, and the halogens (chlorine, bromine, iodine), are not
quantitatively retained. It was also determined from the above studies
that contamination of the sample was not a measurable problem during
ashing. An added advantage to the LTA technique is that resultant samples
are easily composited and homogenized. The complete results of this
research are detailed in Appendix B.
-------
Trace Element Analytical Techniques
The third portion of the current research program has been to evaluate
the effectiveness, and improve where necessary, the major analytical
techniques for environmental samples. The elements specified to be of
primary interest were mercury, lead, arsenic, selenium, nickel, vanadium,
copper, manganese, beryllium, chromium, platinum, and palladium.
Since space does not permit a complete detailing of efforts in this
area, two examples will be selected for brief discussion.
First, a complete study of the determination of chromium by neutron
activation was undertaken. As has been reported recently, there is increas-
ing analytical evidence which suggests the presence of a volatile metallo-
organic chromium species in some types of biological samples. Recent work
on the certification analysis of a candidate NBS SRM of brewer's yeast has
indicated that neutron activation with radiochemical separation is able to
determine reproducibly the stable, as well as the volatile species of
chromium, and obtained excellent agreement with other analytical results
using closed system desolution. A complete description of this work is
given in Appendix C.
The second example is the work at NBS on the modification of published
procedures for the cold vapor atomic absorption determination of Mercury.
Results on the determination of mercury in biological and environmental
samples exhibited a disturbing variability with many results having a
significant error component. A complete investigation into analytical
errors, including losses during sample desolution resulted in a detailed
analytical procedure which now yields consistently reliable results down to
the 50 parts per billion (ng/g) concentration level (4)
-------
SECTION 4
DISCUSSIONS AND RECOMMENDATIONS
The second day of the Tissue Bank Workshop was devoted to a review
of scientific issues and the formulation of recommendations specific to the
implementation of the NESB. On review of the issues that created the need
for the NESB, there was unanimous agreement that not only was the concept
of sample banking still of vital importance to the assessment of low-level
environmental contamination but that many of the original issues which
mandated the implementation of the NESB were heightened due to recent
environmental pollutant episodes. The Kepone episode in the James River
and the Chesapeake Bay was pointed to as a prime example where existing
specimens of documented validity would have been extremely useful to assess
the change in the environment of that pollutant. There were not and are
not Camples of aquatic life or shell fish available from the Chesapeake Bay
or James River which can be used for determination of Kepone levels before
the start-up of the Kepone production in that area. Limited samples were
available from the Virginia Institute of Marine Sciences dating back 3-4
years. These samples have proven invaluable in establishing the extent to
which Kepone has affected the marine life. Had earlier samples been avail-
able from a banking system, a far better assessment of Kepone baseline
levels prior to the dumping episodes would have been available to environ-
mental officials. With the large increase of man-made chemicals now being
put into our environment, it was concluded that issues such as the Kepone
insult in Virginia are surely to be on the increase rather than to remain
as an isolated situation.
A second possible function of the NESB system was raised and found by
the participants to be of vital importance. It was noted that an NESB
system should also include a real-time monitoring function. This function
would provide trend analysis data for the real time estimate of our environ-
mental quality in addition to assessing the effectiveness of our current
pollutant control programs. This could logically be done by subsetting
selected samples that were planned for inclusion in the bank and conducting
real-time analyses on them. This would create an initial environmental
monitoring program with vastly improved state-of-the-art analytical methodol-
ogy. The storage of data produced by this system would also provide a
mechanism for evaluating analytical methods with time. The combination of
time dependent data with the availability of similar samples would allow a
far superior method of quality control.
The single most important point to come from the Workshop was that the
NESB can serve many important functions, not just that of long-term retro-
spective analysis. The results of sample banking would surely impact on
10
-------
monitoring and health affects research of the EPA, and would be of great
assistance to ongoing programs within the Department of Agriculture, Food
and Drug Administration, and other agencies (Figure 1).
A set of specific objectives for the sample bank were identified
during the second day's discussions. Those objectives are summarized as
follows:
1. The collection, preservation, and storage of selected environmental
samples using methodologies that had been documented to minimize
or eliminate alteration of trace constituents.
2. The real-time analysis of selected trace constituents using
methods of documented validity to obtain monitoring trend data.
3. Research in analytical methodology utilizing both the accumulated
long-term data base and samples that have been stored in the
NESB. This research will lead to a self-improving set of
monitoring data.
o
4. The periodic review of the operation of the banking system
relative to its valid input of samples and output of analytical
data.
With the realization that the NESB is a viable concept, both by need and
availability of technology, it was proposed that the NESB be initiated in the
form of a five-year pilot program for banking environmental samples. This
proposal was founded on the realization that a system such as NESB could
quickly become overwhelmed with samples. This would invariably lead to a
breakdown of the physical storage mechanisms, but more importantly, would
likely lead to short cuts and compromises in operating procedures and
analytical methodologies used for this real time monitoring phase of the
system.
This position of moderate growth with careful monitoring of the program
was unanimously recommended by the attendees of the Workshop. It was
further recommended that the pilot program be initiated as soon as was
feasible. During this time, limited numbers of samples would be collected,
analyzed, and stored in a central facility. Problems encountered in the
collection, transportation, analysis, and storage would be carefully
monitored. Any difficiencies found in the system would be reexamined and
new research would be initiated as necessary. With complete accord on the
pilot scale concept, exact guidelines for this system were discussed and
agreed upon.
The identification of specific sample types which should be included
in the pilot sample bank during initial start-up of the system was discussed.
The major focus of attention was on the absolute requirement to minimize
both the number of samples and sample types in the pilot program so that
the banking system did not become overwhelmed with either samples or analyses
during its first years of operation. Unreasonably large numbers of avoidable
errors would destroy its credibility before it was even in full operation.
11
-------
Thus, all participants recommended the inclusion of a modest sample set per
year for the first five years of operation with the focus on validating
credible storage and analytical results.
A reasonable figure of approximately two thousand samples a year,
split into four matrix types, was recommended (Figure 2). Also, it was
recommended that the samples be obtained from no more than two different
locations in the beginning phases, to minimize problems with logistics,
sample collection, and transport.
Nine different sample types representing all major phases of environ-
mental samples were considered for inclusion in the bank. These included
air particulates, sediment, water, botanical, biological, and human samples.
It was recommended that samples which represented environmental accumulators
or integrators be emphasized as initial candidates, both due to the ease of
analytical manipulation of those samples and because they represented time
integrators of major pollutants present in our environment.
The first sample that was recommended for inclusion unanimously was a
soft tissue sample that had an accumulator function in the human body, most
likely liver or kidney. The second and equally important sample type was
an accumulator of aquatic origin. Much discussion centered around the
exact nature of the accumulator and suggestions ranged from plankton to
shark tissue. Agreement was reached that a shellfish bivalve such as
oyster which passes large quantities of water through its system every day
and which tended to mirror increased concentrations of many toxic pollutants
was a good choice. The third sample type was a food material representing
a major input into the human diet. Consensus was unanimous that a food
grain or composite of grains was the best choice. The fourth sample type
was a collector of atmospheric or airborne pollutant materials. It was
recommended that material such as lichen or moss was a good indicator of
long-term trends in atmospheric pollutants and should be included in the
initi-J bank. These four sample types were chosen for their diversity and
their utility to environmental monitoring programs. However, a second and
even more important consideration was that there is now enough scientific
evidence to be reasonably assured that the storage and analysis of the
trace element components in these materials could now be carried out with
integrity.
One of the last items for consideration at the Workshop was the
evaluation and formulation of viable analytical methods for the real-time
and retrospective analysis of samples from the NESB system. Part of the NBS
research effort has been to publish a compilation of analytical methods
currently being used for SRM certification analysis. These methods will be
available in the near future and were discussed at the Workshop. As the
pilot bank program expands, additional analytical laboratories will become
involved in the program. It was the concensus of opinion that rather than
have a single specified analytical method be used on samples from the NESB, a
better approach would be to rely on the judgment of high quality analytical
laboratories to use methodologies that they had demonstrated as viable in
their own laboratories. It is widely recognized that many analytical
methods are capable of producing excellent results in the hands of a
12
-------
talented analyst. However, in the improper hands, standard methodologies
do not necessarily generate credible results. To the contrary, they usually
generate a false sense of security which often leads to monumental mistakes.
It was thus recommended by members of the Workshop that a compilation of
recommended or evaluated methods be included in the NESB system, but these
be included only for the information or aid to the analytical laboratories
actually doing the work. The final decision on methodology would be left
up to the capable laboratories or -scientists working on samples from the
bank. The laboratory capabilities would be under a strict quality assurance
program with blind analyses of representative materials as a foundation.
As a summary to the recommendations and conclusions of the Workshop, a
schematic drawing of the overall NESB system with its functions and respon-
sibilities was put together in a composite form. This schematic represents
most functions and outputs to be derived from the NESB system and is given
in Figure 3. It was concluded by the members of the Workshop that a system
such as this would give reliable data for the evaluation of trends in trace
element and trace organic constituents of environmental and human nutritional
importance over a long period of time.
13
-------
SECTION 5
CONCLUSIONS
There is a real need for the evaluation of sampling, sample handling,
and long-term storage methodology for the establishment of an effective
environmental specimen banking system. This formalized, systematic approach
to defining our current environmental hazards has never before been attempted
on a national scale. Studies are continuing in a randomized fashion and in
many cases without the proper validation of specimen banking procedures.
It is this type of information, however, that is currently being used by
the scientific community as well as State and Federal regulatory agencies
to propose environmental quality standards and limits for control technology.
If these types of monitoring programs are to continue, as they must to
protect our environment as well as the health of our population, then the
type of research program described here is required to establish and define
the necessary basic scientific information required for such a specimen
banking system. The NESB, when operational, will provide future generations
with an important resource for evaluating their current environmental
influences.
14
-------
NESB CONCEPTS
\
ECOLOGICAL INDICATOR
REAL TIME
ANALYSIS
SAMPLE BANKING
RETROSPECTIVE ANALYSIS
NEW POLLUTANTS
IMPROVED METHODOLOGY
FIGURE 1. National Environmental Specimen Bank (NESB) Concepts.
15
-------
PILOT BANK SAMPLES
TWO GEOGRAPHIC LOCATIONS
HUMAJST TISSUE;
AC CU M U L AT- O R<
ATMOSPHERIC
INTERGRATOR:
LICHEN, MOSS,
FILTERS
FOOD
GRAIN
AQUATIC
ACCUMULATOR
SHELLFISH BIVALVE
FIGURE 2. Pilot Bank Samples.
16
-------
NESB PILOT BANK
RESEARCH IN
ANALYTICAL
METHODOLOGY
NESB ADMINISTRATION
REAL TIME
MONITORING
LONG TERM
STORAGE
RESEARCH IN
rfSAMPLE PRESERVATION
AND STORAGE
z
\
RESULTS
TIME SERIAL DATA
FOR TREND ANALYSIS
RESULTS
SAMPLES FOR
RETROSPECTIVE ANALYSIS
L
QUALITY ASSURANCE
TIME DIFFERENTIAL
COMPARISONS
FIGURE 3. NESB Pilot Bank.
17
-------
BIBLIOGRAPHY
1.) NBS Special Publication EPA/NBS/IGA-D5-0568, "Evaluation and
Research of Methodology for the National Environmental Specimen
Bank", D.A. Becker, E.J. Maienthal and G.M. Goldstein.
2.) NBS Technical Note 929, E.J. Maienthal and D.A. Becker.
3.) Anal. Chem., 47, 1685, (1975), S.H. Harrison, P.D. LaFleur, and
W.H. Zoller.
4.) J.O.A.C., 55 No. 6, 1339, (1972),. T.C. Rains and 0. Menis.
18
-------
APPENDIX A
THE CLEANING, ANALYSIS AND SELECTION OF CONTAINERS FOR TRACE ELEMENT SAMPLES
by
J. R. Moody and R. M. Lindstrom
National Bureau of Standards
Institute for Materials Research
Analytical Chemistry Division
Washington, DC 20234
19
-------
used have been given elsewhere (5,6). The bottles were rinsed with distilled
water to remove any surface contamination and three sets of bottles were
filled with a (1+1) mixture of pure HC1 or pure HNC>3 and pure water (7). The
bottles were allowed to stand full for one week, with the exception of the FEP
bottle which was heated to 80 °C for one week.
Aliquots of the contents of one set of bottles leached by (1+1) HC1 were
spiked with 206Pb. Aliquots from two other sets of bottles, leached by (1+1)
HC1 and (1+1) HN03 respectively, were spiked with a 19 element multi-spike (7)
for the spark source mass spectrometer (SSMS). The spiked solutions were then
evaporated to several drops under a Class 100 laminar flow hood. The sample
solutions were then analyzed in the SSMS (multi-element) or thermal source
mass spectrometer (for Pb only).
The first set of bottles were re-filled with a (1+1) mixture of pure HN03
and pure water and the entire cleaning, sampling, spiking, analysis sequence
was repeated as before. Finally, the bottles were filled with high purity 0.5
percent HN03, sampled after one week and again after two months, and then the
aliquots were spiked with 206Pb and subsequently analyzed.
NAA Studies. Specimens of 0.2-2 grams (4-12 cm2) were taken with a steel
paper cutter from new 0.5-1 1 plastic bottles (CPE, LPE, PP, PMP, PC, PVC, and
FEP), sheet (TFE and PFA), bottle caps (ETFE), boxes (PS) or tape (TPT).
Precleaning consisted of a light rinse or wipe with ethanol, and then with
distilled water. Contamination from the steel paper cutter was eliminated
after irradiation.
All irradiations were performed at a thermal neutron flux of 1.3 x 1013 n
cm~2sec~1 and a gamma flux of 2 x 107 rad/hr (8). Other positions in the
reactor offer higher neutron flux, but at the expense of a much higher gamma
flux per neutron. Gamma counting was performed on two large-volume Ge(Li)
detectors. Peaks used for quantitation contained greater than 50 net counts
and better than 25 percent (relative standard deviation) precision from
counting statistics. Signals from many elements were obscured by other
dominant activities, notably Na, Br, and Cl.
NAA Experiment 1: The plastics were each irradiated for two minutes.
After irradiation the edges were trimmed to remove edge contamination and the
samples were counted. Then, the samples were cleaned in (1+1) HC1 by heating
at 100 °C for two hours, rinsed with high purity water, dried, and irradiated
and counted again. After a similar two-hour leach in hot (1+1) HNC^ the
plastics were analyzed a third time.
NAA Experiment 2: Fresh samples from the same plastics were used in
measurements of long-lived activation products. After irradiations (4-6 hrs)
and decay of short-lived activities the edges were trimmed and the plastics
were counted. Then the samples were leached in (1+1) HC1 as before, rinsed,
and leached in hot (1+1) HNOs- The leach solutions and cleaned plastics were
then counted.
22
-------
Results and Discussion
Gravimetric Studies. The results obtained for the materials studied are
given in Table 1. In addition, data previously obtained by Moody, et_ a^, (9)
indicated an annual rate of water loss of ^0.05 percent from one liter Teflon
bottles. PVC, PMP, and PC containers may be excluded from consideration as
container materials due to their high permeability to water. Both Teflon FEP
and PP containers have a rate of loss of less than 0.1 percent per year. CPE
containers lost slightly more than 0.1 percent. Such losses may be minimized
or largely eliminated by sealing the bottle in a bag made of a commercially
available vapor barrier material i.e. polyethylene coated aluminized mylar.
None of the observed loss rates should be construed as permeability data since
the closure may have been responsible for a significant portion of the total
water loss.
All containers used were bought from commercial sources and are believed
to be similar to those most often used in the laboratory. Three of the con-
tainers (PP, FEP, and CPE) have water loss rates which are compatible with the
long term storage of samples while the others (PVC, PMP, and PC) have significant
rates of water loss. The results obtained for CPE are similar to those observed
by Curtis, et_ al_, (10). Humidity conditions during the study averaged about
40 percent R.H. The practice of using a desiccator partially filled with water
to act as a humidity chamber to slow transpiration losses is recommended
although one must be careful that high humidity conditions do not cause a
weight gain (absorption of moisture).
IQMS Studies. The results obtained for the leaching of lead from FEP,
LPE, CPE, and PC containers are listed in Table 2. Lead was chosen as a model
element for this study, partly because of the high accuracy obtainable by
thermal source isotope dilution mass spectrometry. The sequence of using HC1
first and then HN03 conforms to long standing practice in our laboratories (7).
Most of the cleaning of these containers is accomplished by only one week of
soaking in HC1. The additional week of soaking in (1+1) HNC>3 removed additional
lead only from FEP and PC.
Patterson (2) has suggested that. 0.5 percent HMOs is more efficient for
cleaning Teflon containers of Pb contamination than is (1+1) HN03. This was
tried after leaching with (1+1) HNOs no further leaching of lead was detected
except from the PC container. After one month of leaching with 0.5 percent
HNOs, no further lead was leached even from the PC container. The greater
quantity of various elements leached from FEP may be partially explained by
the higher temperature (80° vs room temperature) used to clean the Teflon FEP
container. One advantage of Teflon is that it is chemically inert. The
extent of chemical attack on other materials can be quite severe even at
temperatures only slightly above room temperature.
Data obtained by SSMS is compiled in Tables 3 and 4 for impurities
leached by (1+1) HC1 and (1+1) HN03 respectively. Again, the Teflon FEP
bottles were heated to 80 °C while the others were leached at room tempera-
ture. Generally, the (1+1) HC1 leached more than the (1+1) HN03 except for
the FEP containers. A single element, Ca, is responsible for most of the
difference between the (1+1) HC1 and (1+1) HN03 in leaching Teflon FEP.
23
-------
Values which are below 2 ng/cm2 or which are prefixed by < are upper limit
numbers. That is, the concentration is below the optimunTconcentration range
for the amount of spike isotope used or the concentration is near the blank or
detection limit.
NAA Studies. The amount of impurities found in the uncleaned plastics as
determined in NAA experiments 1 and 2 are summarized in Table 5. A comparison
of the impurities found in CPE in this study shows agreement with that found
by other workers (4,12-16) to approximately an order of magnitude. It is
interesting to note that there has been no clear change in trace elemental
impurities in over 25 years of manufacture (13). The ten materials studied
show striking differences in trace element composition. The purest materials
are TFE and CPE, in agreement with the experience of numerous workers. Poly-
styrene, cut from a box used to package NBS Standard Reference Materials, was
also very clean. Many materials showed easily detectable amounts of a few
elements. Linear polyethylene contained large amounts (>10 ppm) of Na, Al,
Ca, Cl, and Zn; polypropylene-Al, Cl, and Ti; polymethylpentene-Zn; poly-
carbonate-Cl and Br; polyvinylchloride-Na and Sn; Teflon FEP-K (and 1 ppm of
W); Teflon PFA-C1; Teflon pipe tape-Al, Zn, and large amounts of Ti; and ETFE-
large amounts of Cl. Some of these elements are residues of polymerization
catalysts (17).
The results of the acid leaching experiments are presented in Table 6.
They are compiled from the differences in trace element composition of the
plastic after leaching in the first and second NAA experiment, and from direct
measurement of leached tracer in the second. The two experiments are generally
concordant in the conclusion that less than half of most trace elements are
leachable, and quantitatively concordant in the results for sodium, the only
element common to the two NAA experiments. This point is important because
the long irradiation in the second experiment makes those measurements an
imperfect model of a reagent or analyte stored in a bottle.
Those atoms of trace elements leached and detected in the leachate in
the second experiment are precisely those not representative of undisturbed
trace elements in an undisturbed matrix. The radioactive atoms underwent
recoil on absorption of a neutron and thus may have been more labile than
their inactive neighbors. In addition, the matrix suffered radiation damage
from some 108 rads of gamma radiation, with the result that all materials were
visibly browned and their physical properties were greatly changed. The
halocarbons were damaged additionally by the absorption of nuclear recoil
energy and beta radiation induced in major constituents of the matrix. Teflon
TFE and especially pipe tape were perceptibly embrittled, and PVC became black
after the long irradiation.
With the exception of Na .in pipe tape, (perhaps a special case because of
its high surface/volume ratio), and to a lesser extent Na in CPE, the trace
elements studied are in general not leached from the polymer matrix even with
the rather severe acid treatment used here (note that the rule of thumb of a
doubling of reaction rate for every 10 °C rise in temperature makes our condi-
tions correspond to a few weeks' immersion at room temperature). It may be
inferred that generally the bulk of trace elements present are distributed
throughout the matrix, and not merely on the surface.
-------
The hydrochloric acid leach in experiment 1 increased the chloride concen-
tration in all the plastics, but not grossly so. The added chloride contamina-
tion corresponds to a 10"1* cm thickness of 1:1 HC1 in the surface of poly-
propylene, and less in the other materials. Neither this chloride nor other
elements were entirely removed by the subsequent HNC^ leach. This inward
diffusion of HC1 is in accord with the water loss measurements, both experiments
leading to a diffusion coefficient for aqueous solutions in polyolefin of
D=10 1^cm2/sec. If the removal of trace contaminants depends on diffusion of
water as a rate-limiting step, then the inertness of trace elements within the
matrix is explained. With this value of D, the mean square diffusion length
in one year x = /2 Dt =0.1 mm.
The observation that a second leach removes much less contamination than
the first indicates that only surface contamination is easily removed. The
cleanest plastic materials available must be cleaned further for the lowest
blanks. Many methods have been suggested and several have been shown to be
sufficient for the purpose at hand (1,2,7). Since continued cleaning with an
array of purest solvents would continue to clean any container (1)> the ideal
cleaning method will be forever out of reach.
Conclusions
Several commercially available plastic containers have been examined for
rate of transpiration of water. Those which have been found to be suitable
include Teflon FEP, and PP. With a suitable moisture barrier, CPE containers
can also be held to water losses of less than 0.1 percent per year. It is
recognized that there can be considerable bottle-to-bottle variation in wall
thickness and other parameters of construction. Results of the trace element
studies are especially suspect in this regard since even one occlusion in the
container wall can considerably affect the trace element levels.
The containers used for these studies were carefully selected to be free
from visible occlusions and were average in wall thickness, weight, and other
characteristics. While the trace element concentrations found by NAA and IDMS
cannot be said to be statistically representative of all bottles of these
types, the large differences observed between various plastics are probably
valid. In summary, the best containers are believed to be those constructed
of CPE and the various Teflons. Differences were observed between NAA and
IDMS results for trace elements leached from the plastics. At least some of
these differences may be procedural since all the NAA samples were heated
whereas only the FEP samples were heated for the IDMS study.
Another possible difference between the two results may be in the way the
samples were leached. For IDMS work the leaching was carried out within
intact bottles and the results are believed to be representative of the
contamination to which a sample would be exposed in an uncleaned bottle. In
contrast, the NAA studies examined the trace elements leached from both sides
of a small sample of plastic immersed in acid. Since at least some containers
are known to be blow molded, the higher results obtained by NAA may simply
reflect a difference in contamination levels between inside and outside walls,
the NAA data probably including contamination from the mold.
-------
With the exception of Teflon FEP, (1+1) HC1 has been found to be the
better cleaning agent. However, HC1 and WO^ appear to leach various elements
with different efficiencies, thus, the use of both acids one after the other
is recommended. It should not be surprising that in sequential cleaning
studies (for Pb by IDMS, various elements by NAA), most of the cleaning is
accomplished in a short period of time. From the present work, that of Karin
et" al., (16), and other work in this laboratory (3,7) a procedure may be
suggested that is optimum for most trace work: First, fill the containers
with reagent grade (1+1) HC1 and allow them to stand for one week. Empty,
rinse with distilled water, and re-fill the containers with (1+1) HN03 and
allow to stand for another week. Finally, empty, rinse, fill with' the purest
available distilled water, a.nd allow to, stajid until needed. Preferably, the
distilled water "should be changed periodically to assure continued cleaning.
Teflon bottles should be heated through the firs.t, two acid leaches.
Finally, it should be recognized that despite all efforts to clean these
bottles, the data would seem to Indicate that only the surfaces of the container
walls have been cleaned. While very low blank levels may be achieved in a^
relatively short, period of time (several w.eeks), there is insufficient data to
suggest what levels of contamination might occur over a. very long, period of
storage. One possible solution, to this problem, depending upon the sample
involved, would, be to, freeze, the sample for long-term storage.
Then'there is the matter of the; cost o*£ the containexs. Currently,, there,-
is greater than one order, of magnitude, difference in cost between FEP and CPE.
Teflon is the preferred container but its cost often mitigates against its
use. Other plastic materials are available which might be suitable for some
applications. However, we have deliberately chosen to examine only those
materials which are commercially available in suitable containers. The
analyst should keep abreast of changes in materials and methods of fabrication
which wruld have an influence on our results.
Acknowledgement
The authors wish.to acknowledge the contributions of T. J. Murphy,
P. J. Paulsen and J. W. Gramlich for the IDMS.analysis of solutions stored in
plastic containers.
26
-------
LITERATURE CITED
(1) E. J. Mainthal and D. A. Becker, "A Survey of Current Literature on Sampling,
Sample Handling and Long Term Storage for Environmental Materials, NBS
Tech Note 929 (1976).
(2) C. C. Patterson and D. M. Settle, in "Accuracy in Trace Analysis: Sampling,
Sample Handling, and Analysis," Proc. of the 7th IMR Symp., P. D. LaFleur,
ed,, NBS Spec. Pub. 422, 321 (1976).
(3) T. J. Murphy, in "Accuracy in Trace Analysis: Sampling, Sample Handling, and
Analysis," Proc. of the 7th IMR Symp., P. D. LaFleur, ed., NBS Spec. Pub. 422,
509 (1976).
(4) D. E. Robertson, Anal. Chem. 4£, 1067 (1968).
(5) P. J. Paulsen, R. Alvarez, and C. W. Mueller, Applied Spectroscopy 3£, 42 (1976).
(6) I. L. Barnes, T. J. Murphy, J. W. Gramlich, and W. R. Shields, Anal. Chem. 45,
1881 (1973).
(7) E. C. Kuehner, R. Alvarez, P. J. Paulsen, and T. J. Murphy, Anal. Chem. 44,
2050 (1972).
(8) H. E. Despain, private communication.
(9) J. R. Moody, H. L. Rook, T. C. Rains, and P. J. Paulsen, unpublished data from
the preparation of SRM 1642.
(10) G. J. Curtis, J. E. Rein, and S. S. Yamamura, Anal. Chem. 45, 996 (1973).
(11) C. C. Patterson, private communication to E. J. Maienthal.
(12) R. E. Thiers, "Methods of Biochemical Analysis," D. Click, ed., 5_, 274-309,
Interscience, New York (1957).
(13) J. W. Mitchell, Anal. Chem. 4_5_, 429A (1973).
(14) S. H. Harrison, P. D. LaFleur, and W. H. Zoller, Anal. Chem. 4_7_, 1685 (1975).
(15) H. Sorantin and P. Patek, Z. Anal. Chim. 211, 99 (1965).
(16) R. W. Karin, J. A. Buono, and J. L. Fasching, Anal. Chem. 47, 2296 (1975).
(17) E. C. Kuehner and D. H. Freeman, in "PurificationNpf Inorganic and Organic
Materials," M. Zief, ed., Marcel Dekker, New York 1969, pp. 297-306.
27
-------
Table 1. Annual Rate of Loss of Water from Container Materials,
Container . After 17 Days After 66 Days
CPE
PP
PVC
PMP
PC
0.116%
0.034%
0.429%
0.988%
1.65%
0.109%
0.049%
0.601%
1.018%
2 . 00%
Table 2. Lead Leached from Containers (ng/cm2).
Bottle (1+1) HC1 (1+1) HN03 0.5% HN03 0.5% HN03
1 week 1 week 1 week 2 months
0.014
FEP
LPE
CPE
PC
0.41
0.20
0.18
0.36
0.023 0.023
no significant amount over blank level
28
-------
Table 3. Impurities Leached from Plastic Containers by
(1+1) HC1 (ng/cm2).
Elements
Teflon FEP
LPE
CPE
PC
Pb
Tl
Ba
Te
Sn
Cd
Ag
Sr
Se
Zn
Cu
Ni
Fe
Cr
Ca
K
Mg
Al
Na
2
a
2
2
1
0.6
<6
<1
=
0.8
4
6
0.8
16
4
2
1.6
1.0
4
2
0.6
£0.6
1
-------
Table 4. Impurities Leached from Plastic Containers by
(1+1) HN03 (ng/cm2).
Elements Teflon FEP LPE CPE PC
Pb
Tl
Ba
Te
Sn
Cd
Ag
Sr
Se
Zn
Cu
Ni
Fe
Cr
Ca
K
Mg
Al
Na
2
-------
Table 5. Concentrations of Trace Elements in Plastics (yg/g).
Na
Al
Cl
K
Ca
Ti
Mn
Co
Zn
Br
Sn
Sb
La
W
Au
CPE LPE PP
1.3 15 4.8
0.5 30 55
7 30 180
a a
5 0.6a
800
5 60
0.02 0.02
0.04
520
0.02a 0.8 0.005!
0.005 0.2 0.6
0.0001
PMP
0.20 2.2
6.2 0.5
PS
PC
5 1
0.01 0.02
33
0.002a 0.00la
2.7
3.0
50
0.006'
29
PVC TFE
20 0.16
0.23
major
0.0003
0.0006 0.00004a 0.000033
0.006a 0.002a
2400
0.0006
0.0003
FEP PFA TPT ETFE
0.40 0=1 2.3 0.6
0.20 29
0.8 50 7 1000
93 3 1.1
2000
0.06 0.02 0.02
0.09
14
0.16 0.24
0.7
0.001'
0.0002a 0.0004a
Certain elements were detected only in leach liquids. 2l*Na or 82Br usually predominated in the
plastics even after cleaning, consequently trace elements not removed from the matrix were not
determinable; starred concentrations are lower limits. Blank spaces imply that the element was
not detected.
-------
Table 6. Sequential Leaching of Trace Elements from Plastics (ng/cm2)a.
tsJ
CPE
LPE
PP
PMP
PS
PC
PVC TFE FEP PFA TPT
ETFE
Ma 200+0.4 70+1 100+7 20+0.4 20+8 20+1 30+10 80+ 60+ 20+ 50+4 300+1
Al 50+
K 1000+ 100+ 80+ 90+ 400+
Co +2
Zn . 50+30 20+
Br 3+ 2+0.5 1+ 1+ 0.3+0.1 7+20 2+ 10+
Sb 1+ 3+
La 0.1+ 0.4+ 0.7+
W 4+0.2
Au 0.03+0.01 0.01+ 0.01+ 0.3+ 0.01+ 0.3+0.01
The notation "N+M" implies that N ng of the element in question was leached from 1 cm2 of the
plastic by hot (1+1) HC1 in one hour, and M ng subsequently leached by (1+1) HN03. Blank spaces
imply that the element was not detected.
-------
APPENDIX B
EVALUATION BY ACTIVATION ANALYSIS OF ELEMENTAL RETENTION
IN BIOLOGICAL SAMPLES AFTER LOW TEMPERATURE ASHING
by
George J. Lutz, John S. Stemple and Harry L. Rook
Activation Analysis Section
Analytical Chemistry Division
National Bureau of Standards
Washington, D.C. 20234
33
-------
INTRODUCTION
Low temperature ashing (LTA) is the low temperature (MOO °C) decomposi-
tion of organic or biological samples with atomic oxygen produced by an
electrodeless radio-frequency (RF) discharge. There are a number of
advantages in using LTA as the first step in an analytical method whether
by nuclear activation or otherwise:
1. Since the oxidation temperature is low, volatility losses are
minimized during the destruction of large quantities of organic material.
2. There are no electrodes to contaminate the sample.
3. A sample can be more readily dissolved after LTA than by alternative
methods. 'Wet ashing techniques with hot oxidizing acids or strong alkalis
are potentially hazardous, sometimes incomplete, and usually susceptible
to contamination because of the large amounts of reagents required.
4. High temperature ashing in a muffle furnace introduces the
possibility of contamination from containers or the furnace walls as well
as loss of some elements by volatilization. The convenience of the LTA
methor1 can be demonstrated by reference to a publication concerning the
spectrophotometric determination of boron extracted from ashed animal
tissues (1). Four grams of freeze-dried tissue were ashed 40-50 hours at
100-150 watt forward RF power. After the LTA treatment, the sample could
be dissolved in 2 ml of IN HC1.
5. In the X-ray fluorescence method, which is strongly matrix
dependent, LTA reduces the sample to a silicate-carbonate-oxide form,
which minimizes errors due to that problem.
6. In spark-source mass and emission spectrometry the ashed residue,
when mixed with powdered graphite, gives a uniform consistency which also
reduces matrix error.
With specific respect to activation analysis, one can identify several
advantages of beginning the analysis of a biological sample with freeze-
drying followed by LTA.
1. A very high neutron flux can badly char a biological or organic
sample leavig it with an undesirable consistency. That the LTA method is
very efficient for removing organic carbon is demonstrated by an American
Society for Testing and Materials procedure (2) which specifies the technique
34
-------
in removal and hence determination of organic carbon as opposed to carbonate
in sediment samples.
2. LTA results in a substantial reduction in the volume of the
sample. This can yield a corresponding reduction in electron accelerator
or neutron generator irradiation time in photon or 14-MeV neutron activation
analysis.
3. Since lengthy wet digestions are eliminated, a sample after
irradiation can be dissolved more quickly and hence short-lived nuclides
can be more quickly separated from the sample for counting.
4. In the instrumental photon activation analysis of samples containing
large amounts of carbon, it is usually necessary to delay counting for a
few hours after irradiation to allow the J1C produced by the reaction
12C(y, n)1^ to decay. Some shorter-lived nuclides are therefore not
detected. Many of them could be detected by removal of the carbon prior
to irradiating.
The possibility exists in the LTA method of the loss of elements of
interest during the ashing process. Studies to evaluate elemental reten-
tion during ashing have been conducted with radioactive tracers (3). This
is not an entirely satisfactory procedure since a number of elements may
not be present in a biological sample in the same chemical form as was
used in the tracer studies. This paper describes a study, using activation
analysis, of loss or contamination of trace elements during LTA. It is
hoped that this will be useful not only in analytical chemistry for the
reasons listed above, but also to evaluate LTA as a potential processing
method for the retention of biological samples by the National Environmental
Sample Bank over several decades of time for purposes of baseline studies
to evaluate increases or decreases in pollution.
EXPERIMENTAL
A commercial model LTA apparatus capable of 100 watts forward power
was used in these experiments. A schematic of the apparatus is shown in
figure 1. The sample was placed in a borosilicate glass ashing chamber
which was briefly rotated by hand to induce the organic sample to spread
as evenly as possible on the inside surface. The cold trap was filled
with crushed dry ice (liquid nitrogen would condense explosive ozone).
The system was pumped down to 1.3-2.6 Pa (10-20 millitorr). The oxygen
flow rate was adjusted so as to maintain a pressure of 13-40 Pa (100-300
millitorr). Forward power was usually set to the maximum of 100 watts.
Tuning to optimum was accomplished by observing the maximum intensity in
discharge glow in the tube.
. 35
-------
BOROSILICATE GLASS ASHING CHAMBER
VACUUM GAUGE
f '
TO
VACUUM -«=
±
. 1
VALVE
REGULATOR
DRY ICE
COOLED TRAP
RF GENERATOR AND
TUNING CONTROLS
OXYGEN CYLINDER
Figure 1. Block diagram of LTA apparatus.
Preliminary experiments involving addition of tracers to biological
materials and determining retention of each isotope after ashing verified
previously published data (3) and served to establish and perfect the
basic ashing technique. After these experiments, it was decided to study
three NBS Standard Reference Materials in detail; 1571-Orchard Leaves,
1577-Bovine Liver, and 1632-Trace Elements in Coal.
Samples of about one gram were ashed for a period of several hours.
It was impossible to remove all of the ashed material from the tube, thus
it was necessary to determine the exact amount of material removed. This
was first attempted by weighing of the tube which proved difficult, since
the only balance capable of accommodating the 200 g in weight, 30 cm in
length ashing tube was accurate to only ± 2 mg. A second and more successful
technique involved the use of a nonvolatile radioactive tracer that wouldn't
36
-------
interfere with later activation analysis. The uniform distribution of the
tracer throughout the bulk sample was demonstrated by taking several small
samples from the bottle and measuring their specific activities. Subsequently,
it was found possible to use the activation product of an element demonstrated
to be nonvolatile as an internal standard for this purpose.
The relative amounts of the elements in ashed and unashed samples
were determined by nondestructive neutron activation analysis with the NBS
10 megawatt nuclear reactor and photon activation analysis with the NBS
electron linear accelerator.
For the reactor irradiation a paired experiment was carried out using
approximately one gram of unashed material compared to the ashed residue
of one gram of material. Three series of neutron irradiations were conducted:
1. Fifteen-second irradiation followed by three countings at few
minute intervals,
2. Twenty-minute irradiations followed by 2-3 countings over a
period of one hour to a few days,
3. A four-hour irradiation followed by 2-3 countings over a period
of several days to a few weeks after irradiation (depending on Na-24
levels).
The two shorter irradiations were conducted at a flux of 1.3xl013n-cm~2-sec"1,
and the longer irradiation at a flux of 5.6xl013n-cm 2-sec *.
Two series of photon irradiations were conducted with approximately
three grams of unashed material and the ashed residue of three grams of
material with an electron energy of 35 MeV and a beam current of about 50
yA.
1. Thirty to sixty minute irradiation followed by 2-3 countings
over a period of two hours to a few days after irradiation,
2. Two to six hour irradiation followed by 2-4 countings over a
period of two days to a few weeks after irradiation.
Irradiated samples were counted with a 75 cc Ge(Li) detector and a 4096
channel analyzer using one-half of the memory. Molybdenum, iodine, and
zinc by photon activation analysis were also determined with a low energy
photon detector (LEPD). Photopeak counting rates were corrected for times
of irradiation and decay and ratio of weights of unashed material and
ashed residue corrected for weight loss.
37
-------
RESULTS AND DISCUSSION
The experimental study of the observation of ashing losses was carried
out in three phases. The first consisted of spiking samples of interest
with radioactive tracers of known chemical states. This phase was simple
to conduct as the isotopes could be so added to avoid interference in
radioactive counting. This first phase severed to assist in development
of handling techniques for subsequent work. The results with radioactive
tracers showed the retention of zinc, cadmium, arsenic, palladium, rhenium,
antimony, iron, platinum, iridium, gold, and silver. A previous paper (3)
had reported the loss of gold and silver but this phenomenon was not
confirmed here. Mercury and osmium were lost after several hours of ashing
in every case.
The second phase consisted of irradiating portions of the three
samples, counting them, then ashing and recounting. These experiments
added to the retention list the following elements: sodium, potassium,
rare earths, and selenium.
The third phase, which was the major part of this study, involved the
simultaneous activation, either by thermal neutrons or high-energy photons,
of an untreated portion of the samples and an ashed portion. This study
thus established loss data on elements in the chemical form they would
actually be found in three representative matrices. Table 1 gives typical
weight losses and carbon losses as measured by the photonuclear reaction
11C(Y,an)7Be for an ashing period of approximately 12 hours and power of
approximately 70 watts. In addition to carbon, the loss of chlorine,
bromine, and iodine was observed in all three matrices as well as the
expected loss of mercury. Table 2 gives experimental recoveries of
retained elements.
TABLE 1. TYPICAL WEIGHT AND CARBON LOSSES FOR ASHING PERIODS OF
15 HOURS AND RF POWER OF 70 WATTS
Coal
Beef Liver
Orchard Leaves
% Weight Lost
80
90
75
% Carbon Lost
75
98
80
38
-------
Figure 2 shows, in the formate of the periodic chart, the elements
detected and not lost during ashing in all experiments. The symbols
in the individual square of each element, OL, C, and BL stand for
orchard leaves, coal, and beef liver, respectively, in which the
element was determined. In addition, some elements reported retained
in the literature determined by neutron activation analysis (4),
atomic absorption spectrometry, (5) or spectrophotometry (1) are
included. The numbers refer to references.
H
LI
NA
C
OL
BL
K
C
OL
RB
c
OL
BL
cs
c
OL
BL
FR
BE
MG
c
OL
BL
CA
C
OL
BL
SR
c
OL
BA
c
OL
BL
RA
SC
c
OL
BL
Y
LA
C
OL
BL
AC
Tl
C
OL
ZR
C
OL
HF
C
OL
V
C
NB
TA
c
CR
C
OL
BL
MO
OL
BL
w
c
MN
c
OL
BL
TC
RE
FE
c
OL
BL
RU
OS
CO
C
OL
BL
RH
IR
Nl
C
OL
PD
PT
CU
5
AG
4
AU
ZN
C
OL
BL
CD
5
HG
B
1
AL
c
OL
BL
GA
c
IN
TL
5
C
SI
GE
SN
PB
c
OL
N
P
AS
C
OL
SB
c
OL
BL
Bl
O
S
SE
c
OL
BL
TE
PO
F
CL
BR
I
AT
HE
NE
AR
KR
XE
RN
CE
c
OL
BL
TH
c
OL
BL
PR
PA
NO
U
PM
NP
SM
PU
EU .
c
OL
BL
AM
GO
CM
TB
BK
DY
CF
HO
ES
ER
FM
TM
MO
YB
NO
LU
LW
1. J.W. Mair, Jr., and H.G. Day, Anal. Chem. 44 (1972) 2015. Matrix was animal tissue.
4. D.Behne and P.A. Matamba. Z. Anal. Chem. 274 (1975) 195. Matrix was blood serum.
5. B.B. Stafford, Proceedings 2nd Conf. Trace Subs, in Environmental Health (1968) Univ. of Mo.
Matrix was atmospheric paniculate.
Figure 2. Elements retained during LTA.
Although some of the results have been previously reported, we include
data here on many additional elements, including those particularly
susceptible to loss such as arsenic, selenium, and chromium, since they
are known to form compounds which are volatile at the temperatures of LTA.
39
-------
TABLE,2.. PERCENT OF ELEMENT RETAINED (EXPERIMENTAL)
Coal Orchard Leaves Beef Liver
Sodium 98 100 104
Magnesium 98 101 95
Aluminum 105 - 112
Potassium 101 106
Calcium 99 101 99
Scandium 100 101
Titanium 105 99
Vanadium 98
Chromium 99 106 94
Manganese 102 102 105
Iron 96 102 99
Cobalt 108 95 106
Nickel 99 99
£inc 107 102 100
Gallium 91
Arsenic 110 92
Sel'enium . '99 105
'ftufcidlifln 98 98 92
Strontium 98 106
Zirconium 104 108
Molybdenum 93 94
Antimony 104 108
Cesium 102 104
Barium 105 109
Lanthanum 107 95 95
Cerium 99 98 100
Europium 98 - 94
Hafnium 96 '98
Tantalum 109
Tungsten 97 -
Lead 106 97
Thorium 103 92
It is also significant to note that, equal in importance to loss of
trace elements, there was no pick-up of contamination during the ashing
process as would be evidenced by an increase in the amount of the element
after ashing. This is in spite of the fact that only very ordinary precautions
were taken to guard against contamination during cleaning of the borosilicate
glass ashing tube with ordinary laboratory detergent followed by rising
with water, hot dilute hydrochloric acid and finally deionized water and
drying in an oven at 100 °C.
40
-------
An application of immediate interest is those elements which upon
thermal neutron or photon activation yield radioisotopes with half-lives
in the range of 2-30 minutes and are not detectable in the typical biological
sample without separation. Since after ashing, biological samples, especially
animal tissue, are rapidly dissolved in dilute mineral acid, one may
consider radiochemical separations in the determination of magnesium,
aluminum, titanium, and vanadium in the case.of thermal neutron activation
and potassium and iron in photon activation.
41
-------
ACKNOWLEDGMENTS
The authors thank the operating staffs of the NBS research reactor
and electron LINAC for the fine services provided. This work was supported
by the Environmental Protection Agency.
42
-------
REFERENCES
1. J.W. Mair, Jr., and H.G. Day, Anal, Chem. 44, (1972) 2015.
2. V. Janzer, Private Communication.
3. C.E. Gleit and W.D. Holland, Anal. Chem. 34_, (1962) 1454.
4. D. Behne and P.A. Matamba, Z. Anal. Chem. 274, Q975) 195.
5. B.B. Stafford, Proceedings 2nd Conf. Trace Subs, in Environmental
Health (1968) Univ. of Missouri.
43
-------
APPENDIX C
DETERMINATION OF CHROMIUM IN BIOLOGICAL MATRICES BY NEUTRON
ACTIVATION: APPLICATION TO STANDARD REFERENCE MATERIALS
by
L.T. McClendon
Analytical Chemistry Division
National Bureau of Standards
Washington, D.C. 20234
44
-------
ABSTRACT
Chromium is recognized to be an essential trace element in several
biological systems. It exists in many biological materials in a variety
of chemical forms and very low concentration levels which cause problems
for many analytical techniques. Both instrumental and destructive neutron
activation analysis were used to determine the chromium concentrations in
Orchard Leaves, SRM 1571, Brewers Yeast, SRM 1569, and Bovine Liver, SRM
1577. Some of the problems inherent with determining chromium in certain
biological matrices and the data obtained here at the National Bureau of
Standards using this technique are discussed.
45
-------
INTRODUCTION
Chromium has been recognized as an essential trace element (1) in
human nutrition for several years. At high concentrations or in different
chemical states it can also cause deleterious or toxic effects. There is a
need for reliable methods of analysis for chromium at trace levels in a
variety of matrices, especially biological matrices. A laboratory inter-
comparison on environmental materials (2) pointed up the sad state of
chromium determinations as performed by most of the analytical community.
Also, the author has observed a wide range of results reported for chromium
in the National Bureau of Standards (NBS) Bovine Liver Standard Reference
Material (SRM 1577). As a result of these observations and communication
with several analytical laboratories involved in the determination of
chromium in biological matrices, persons at NBS became convinced that more
biological materials needed to be analyzed and certified for chromium
content, in addition to other elements.
Neutron activation analysis, both instrumental (INAA) and destructive
(DNAA), has been used to determine the chromium concentration in a variety
of matrices. The results obtained for chromium in three biological Standard
Reference Materials (SRM's)—Orchard Leaves, Bovine Liver, and Brewers
Yeast--are described in this paper. The chromium content has been certified
by NBS in two of these SRM's, Orchard Leaves and Brewers Yeast.
EXPERIMENTAL
Samples Analyzed
Two of the biological materials analyzed were NBS Standard Reference
Materials Orchard Leaves CSRM 1571) and Bovine Liver (SRM 1577). The
third material, Brewers Yeast, was furnished to NBS by the Nutrition
Institute, U.S. Department of Agriculture, Beltsville, Maryland, for
preparation, certification, and issuance as a Standard Reference Material.
This material is certified for total chromium concentration only and is
being prepared for sale by the NBS Office of Standard Reference Materials
as SRM 1569.
Preparation of Standards and Carrier
Two standards were used in this work. One standard was prepared by
dissolving a weighed amount of chromium metal (99.99% pure) in high purity
HC1 and diluting to a specific volume with high purity H20 to obtain the
desired Cx concentration. The second standard was prepared by dissolving
46
-------
a weighed amount of NBS-SRM 136C (K2Cr207) in high purity H20 and diluting
to volume to obtain the desired Cr concentration. Chromium carrier solutions
were prepared from analytical reagent grade CrC 13 and K2Cr207 and normally
contained 3 mg Cr/ml.
All reagents used in the analysis were of analytical grade, unless
stated otherwise.
Irradiation Conditions
Chromium was determined in the three biological materials using both
INAA and DNAA. The samples (200-350 mg) along with Cr standards were
encapsulated in clean quartz vials and irradiated for periods of one to
six hours in the NBS Reactor at a thermal neutron flux of Ixl013n cm~2«sec~1.
The samples were allowed to decay 3-6 weeks for INAA work and ^36 hours
for DNAA work to reduce the matrix activity before processing.
Procedure for INAA
Following a three-week decay the sample vials were washed clean of
exterior contamination with 1:1 HN03 and H20", frozen in liquid nitrogen
opened, and the material was transferred to clean polyethylene counting
vials. The amount of sample transferred was determined by weight. The
samples and standards were counted on a 75 cm^ Ge(Li) detector coupled to
a-4096 channel pulse heigvht analyzer for measurement of 51Cr produced by
the 50Cr(in,Y) 5*Cr reaction. The concentration of chromium was determined
by the direct-comparator method.
Several brewers yeast samples and standards were preweighed into
clean quartz vials, sealed, and irradiated as already described. After
allowing these samples to decay for ^6 weeks, the vials were washed clean
of exterior contamination and counted (material still contained in vial)
as clready described.
Procedure for DNAA
Following a 36-hour decay, the sample and standard vials were cleaned,
frozen in liquid N2, opened, and transferred (by weight) to a 50 ml Erlenmeyer
flask designed for dissolving materials in a closed system (3) and trapping
volatile material in an external solution. Chromium carried (^5 mg of both
Cr III and Cr VI) and 5-10 ml of concentrated HClO^-HNOs mixture (1:3)
were added to the flask. The flask was heated on a Pyrex top hot plate
until all the sample had dissolved and all the vapor fumes visibly trapped
in a 1:1 HN03 solution. The flask was removed from the heat and 5 ml of
hot Ce(SOtt)2-3M ti^SO^ solution (10% w/v) was added; the flask was heated
an additional 5-10 minutes to assure oxidation of and maintain the chromium
as Cr VI. After cooling, the sample solution in the flask was transferred
to a 50-ml extraction tube with 15 ml of 1.5 M HC1. The sample was then
extracted with 10 ml of 1 percent (w/v) tribenzylamine-chloroform solution.
A 5-ml aliquot was taken from the organic phase and counted on a 25 cc
Ge(Li) detector coupled to a HP 4096 computer-analyzer. The trap solution
47
-------
from the dissolution step was transferred to a suitable counting vessel
and counted on this system also. The 320 keV gamma ray peak of 51Cr was
integrated and the chromium concentration was determined by the direct-
comparator method using the two chromium standards subjected to the same
procedure. All of the chromium from these standards remained in the
flask. The trap solution was checked for chromium but none was detected.
The procedure is the same for open-flask dissolution of samples except a
regular Erlenmeyer flask is used, eliminating the trap solution.
Results and Discussion
Recent interlaboratory comparison studies (4>5) of analytical methods
and their results for the analysis of chromium in biological and environmental
materials showed very large differences in analytical values. During the
spring of 1974, a workshop on chromium analysis was held at the University
of Missouri in Columbia where these differences were discussed and recommen-
dations made to resolve them. There was consensus among the participants
that biological standard reference materials, certified for total chromium
content by NBS, would provide a starting point for the analytical community
to critically evaluate their methods..
Chromium has been determined and certified in several materials by
NBS. However, this manuscript describes the results of chromium analyses
in three biological materials—Orchard Leaves, Bovine Liver, Brewers
Yeast--using neutron activation analysis (NAA). Studies here in our
laboratory and other laboratories (6,7) on some biological materials had
suggested possible losses of chromium content during sample manipulation
(e.g., dissolution, charring, ashing, etc.). Instrumental neutron activation
analysis (INAA) and destructive neutron activation analysis (DNAA) was
used to determine the chromium concentration in these biological materials.
The use of INAA to determine the total chromium concentration in these
biologicals provided an "absolute" check for the values obtained using
DNAA and also other techniques which required sample treatment. The
results obtained for chromium in the three biologicals mentioned above,
using NAA and the NBS Reactor, are given in Tables 1-4.
By employing two dissolution techniques—closed system and open
flask--for the irradiated biologicals, the loss of chromium in the dissolution
step could be evaluated. The results obtained for chromium in Orchard
Leaves (Table 1) were essentially the same using INAA and the two dissolution
techniques, indicating no chromium is lost from this material in the
dissolution procedures used. The slightly higher INAA result for chromium
is expected. A large amount of matrix radioactivity is produced when
these biological materials are irradiated. Much of this activity results
in long-lived beta radiation creating a bremsstrahlung effect in the gamma
spectra when the sample is counted. This effect is very dominant in low
energy range of the spectra where the chromium photopeak is located so
that large background corrections are necessary. Radiochemical separation
of Cr (DNAA) eliminates the background interference. The results obtained
from open-flask dissolution (DNAA) of yeast (Table 2) were consistenlty
lower (^25%) than those obtained instrumentally (INAA). The results
48
-------
obtained from dissolution of brewers yeast in a closed system as described
in the DNAA procedure are in good agreement with the INAA results. The
same phenomenon existed in the determination of chromium in bovine liver
(Table 3).
The results in Tables 1-3 show chromium can be lost during sample
dissolution of two biologicals, brewers yeast and bovine liver. However,
no loss of chromium was observed in our experimental design for orchard
leaves. The chromium loss observed in brewers yeast and bovine liver is
probably an organic component, since there was apparently no exchange with
the inorganic chromium added to the sample before dissolution. Further
studies to characterize this component are underway in this laboratory.
Brewers yeast was preweighed, packaged, irradiated, and counted in
the same container in order to establish that chromium was not lost in the
irradiation step. The results in Table 4 show the amount of chromium
obtained using a-polyethylene irradiation container (INAA-P.E.) are in
good agreement with those obtained from a quartz irradiation container
(INAA-Quartz).
The radiochemical procedure described for chromium (DNAA) provides
the analyst with a simple, rapid, and selective technique for chromium
determination in a variety of matrices. The procedure is also adaptable
for use by other techniques. Results of chromium analysis (jfroro a variety
of techniques) reported in the literature in recent years show very large
differences in concentration on the same materials. Thus, it is hoped
these two biological materials, certified for total chromium concentration,
will help those involved in chromium analysis to evaluate their methods
and improve chromium results reported in the literature and elsewhere for
analytical quality control samples.
49
-------
REFERENCES
1. W, Mertz, Physiol. Rev., 49_ (1969) 163.
2. L. McClendon, Trace Subst. Environ. Health, £ (1974) 255.
3. D.A. Becker and G.W. Smith, Mod. Trends in Activ. Anal. Conf., College
Station, Texas (1965) 230.
4. J. Pierce, et al, Symp. on the Development of Nucl. Based Tech. for
Meas., Detection and Control of Environ. Pollutants, Vienna, Mar.
1976.
5. R. Parr, Mod. Trends in Activ. Anal. Conf., Munich (1976) 1414.
6. V. Maxim, et al, symp. Nucl. Activation Tech. in the Life Sciences,
Bled, Yugoslavia, April, 1972.
7. W. Wolf, Interface, 2 (1973) 31.
50
-------
TABLE 1. CONCENTRATION OF CHROMIUM IN ORCHARD LEAVES,
SRM 15.71. Cvg Cr/gram)
Spl #
1
2
3
4
5
6
INAA
2.590
2.574
2.563
2.567
2 . 569
2.582
DNAAA
2.514
2.489
2 . 4,99
2.495
2.501
2.472'
DNAAB
2.472
.2.4.47
2.484
2.433
. 2.463
2.481
X 2.574 ± 0.010 2.495 ± 0.014 2.463 ± 0.020
* NBS Certified Value: 2.6 ± 0.2. yg/g
Note: A - Closed system dissolution.
B - Open flask dissolution.
* Based on results of two independent analytical methods
This work and isotope dilution mass spectrometry.
51
-------
TABLE 2. CONCENTRAION OF CHROMIUM IN BREWERS YEAST,
SRM 1569 (yg.Cr/gram)
Spl #
1
2
3
4
5
6
INAA
2.079
2.075
2.090
2.077
2.067
2.104
A
DNAA
2.070
2.068
2.062
2.068
2.088
2.090
R
DNAA
1.583
1.543
1.548
1.588
1.551
1.565
X 2.082 ± 0.013 2.074 ± 0.012 1.558 ± 0.015
NBS Certified value: 2.12 ± 0.05 yg/g — Based on results of two
independent analytical methods—This work and
isotope dilution mass spectrometry.
Note: A - Closed system dissolution.
B - Open flask dissolution.
52
-------
TABLE 3. CONCENTRATION OF CHROMIUM IN BOVINE LIVER
SRM 1577 (yg Cr/gram)
Spl #
1
2
3
4
:5
6
INAA
0.228
0.170
0.229
0.242
0.177.
0.213
; .. 'A
DNAA
0.212
0.209
0.210
'0:207
i
•0 . 214
6.209
• B
DNAA
0.157
0.166
0.153
0.156
0.166
0 . 160
O.Z10 ± 0.030 0.210 ± 0.002 0.160 ± 0.005
Note: A - Closed system dissolution.
B - Open flask dissolution.
53
-------
TABLE 4. CONCENTRATION OF CHROMIUM IN BREWERS YEAST,
SRM 1569, Using INAA (pg Cr/gram)
Spl #
1
2
3
4
5
6
INAA - P.E.
2.079
2.105
2.117
2.081
2.120
2.075
INAA - Quartz
2.131
2.087
2.137
2.092
2.149
2.120
2.096 ± 0.020 2.119 ± 0.025
54
-------
TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing)
1. REPORT NO.
EPA-600/1-77-020
3. RECIPIENT'S ACCESSION-NO.
4. TITLE AND SUBTITLE
RECOMMENDATIONS OF THE EPA/NBS WORKSHOP ON THE
NATIONAL ENVIRONMENTAL SPECIMEN BANK
5. REPORT DATE
April 1977
6. PERFORMING ORGANIZATION CODE
7. AUTHOR(S)
Harry L. Rood and *George M. Goldstein
8. PERFORMING ORGANIZATION REPORT NO
9. PERFORMING ORGANIZATION NAME AND ADDRESS
National Bureau of Standards
Washington, D.C. 29234, and
*U.S. Environmental Protection Agency
Research Triangle Park, N.C. 27711
10. PROGRAM'ELEMENT NO.
1AA601
11. CONTRACT/GRANT NO.
IAG-D4-0568
12. SPONSORING AGENCY NAME AND ADDRESS
Health Effects Research Laboratory - RTP, NC
Office of Research and Development
U.S. Environmental Protection Agency
Research Triangle Park, N.C. 27711
13. TYPE OF REPORT AND PERIOD COVERED
14. SPONSORING AGENCY CODE
600/11
15. SUPPLEMENTARY NOTES
16. ABSTRACT
On August 19. and 20, 1976, the National Bureau of Standards and the U.S.
Environmental Protection Agency co-sponsored a Workshop to review technical develop-
ments and to make recommendations on implementation of the National Environmental
Specimen Bank. The Workshop consisted of a review session where past considerations
were discussed; a technical session where recent analytical research relevant to the
des?™ ^ WaS abstracted and discussed; and a planning session where planning and
design of a prototype banking system was outlined.
PSUniry presentations> discussion, and conclusions of
The Commission of European Communities and the U.S. Environment^!
Protectr.on Agency) and the Federal Republic of Germany.
The workshop concluded that with the ever increasing influx of new man-made
substanced into our ecosystem, that formalized, systematic approach is needed to
assess the environmental impact of these substances on a national as well as an
international level. The technology to initiate a pilot banking program is presently
available and was formulated into a five-year pilot bank program." This program will"
be evaluated at each stage of development. _ _ F ^ram win
7.
KEY WORDS AND DOCUMENT ANALYSIS
DESCRIPTORS
b.IDENTIFIERS/OPEN ENDED TERMS C. COSATI Field/Group
meetings
data acquisition
information centers
environmental surveys
specimen bank
05 b
06 f
3. DISTRIBUTION STATEMENT
RELEASE TO PUBLIC
19. SECURITY CLASS (This Report!
UNCLASSIFIED
21. NO. OF PAGES
20. SECURITY CLASS (This page)
UNCLASSIFIED
J6L
22. PRICE
EPA Form 2220-1-(9-73)
55
------- |