WATER QUALITY--Acceptability and Use of Water-Quality Analytical Methods
In Reply Refer To: January 21, 1982
EGS-Mail Stop 412
WATER RESOURCES DIVISION MEMORANDUM NO. 82.28
Subject: WATER QUALITY--Acceptability and Use of Water-Quality
Analytical Methods
This memorandum is a statement of Division policy on acceptability
and use of analytical methods for determination of water-quality
constituents. It supersedes Quality of Water Branch Technical
Memorandum No. 79.11 (March 19, 1979) which set forth requirements
for approval of such methods. This statement updates the approval
requirements to reflect the responsibility of the Central
Laboratories to confirm the validity of new or modified methods
developed for official use in the Central Laboratories System. It
also formalizes the previously unwritten policy of alternate
method equivalency as applied to Central Laboratory operations.
The Water Resources Division (WRD) recognizes two types of water-
quality analytical methods--Approved Methods and Special Methods.
Definitions of the two types of methods and requirements for
approval of analytical methods are given below.
Approved Methods
Two categories of approved analytical methods have been formally
established. These are: (1) official methods, and (2)
provisional methods. A description of each of these categories
and requirements for their approval are given below:
Official Methods--Methods in this category are considered to be
the official water-quality analytical methods of the WRD. They
are or will be published in the Techniques of Water Resources
Investigations (TWRI) series. Data collected by these methods may
be stored in WATSTORE and published in the annual basic data
reports of the WRD.
Requirements for approval are:
1. Submission of documentation of the proposed method or
modification of a presently used method in TWRI format to the
Chief, Quality of Water Branch.
2. Submission to and approval by the Quality of Water Branch of a
method-development report giving information and supporting
data on the following:
(a) applicable range, detection limit, and sensitivity of the
method,
(b) known and possible interferences,
(c) precision and bias of the method; these data should as a
minimum include: (1) single-laboratory and multiple-
operator tests which include at least 10 replicate
analyses each of pure solutions, natural water, and
spiked natural waters at three concentrations covering
the applicable range of the method,
(d) production rates compared to other methods, when
possible.
3. Submission of statements describing hazardous chemical
reactions and/or reagents that are involved in the method,
sample preservation requirements, and level of skill and/or
special training requirements needed by personnel using the
method.
4. In addition to the above minimum requirements for approval, if
it is determined that the proposed method will be used in the
Central Laboratories System, the Quality of Water Branch will
initiate plans to obtain technical reviews of the method
documentation and method development report by at least two
colleagues, one of which must be outside the author's
laboratory. In addition, if the method is developed in one of
the Central Laboratories, the other Central Laboratory will be
expected, if they have the equipment, to confirm the precision
and bias of the method and to compare results with present
methodology if a method exists. These requirements must be
completed within 30 days. Approval of the method will be
dependent on obtaining the reviews and additional data. The
Quality of Water Branch may give Provisional Approval as
outlined below during the period of review.
Provisional Methods--Methods in this category are believed to
produce data comparable to those obtainable from official methods
but are likely to be used by WRD to such a limited extent that
they have not received extensive inhouse testing by WRD personnel.
Many of the methods published in such reliable compendia as
Standard Methods, Environmental Protection Agency Methods for
Chemical Analysis of Water and Wastes, and the American Society
for Testing and Materials Book of Standards, and which are used by
inhouse, cooperator, or contractor laboratories in support of WRD
programs, would be accepted for approval in this category. These
methods will not be published in the TWRI series. Data collected
by these methods may be stored in WATSTORE if a parameter code
exists, and the data may be published in the annual basic data
reports.
Requirements for acceptance of methods in this category are as
follows:
1. Submission of a copy of the method to the Chief, Quality of
Water Branch, with an explanation of why approval of the
method is desired.
2. Provision of the same type of information on precision and
bias as required for Official Method approval; however, in
this case, data obtained by other than WRD personnel will be
acceptable for consideration.
Request for approval of water-quality analytical methods should be
submitted to the Chief, Quality of Water Branch, with copies to
the appropriate Regional Hydrologist. The request should be
accompanied by supporting documents appropriate to the category of
approval that is requested.
The Quality of Water Branch will maintain a listing of all
approved methods and periodically will distribute to the field a
list of all approved methods which have not been published in the
TWRI series.
Special Methods
In contrast to the two categories of approved analytical methods,
there are some methods that have specialized or limited
application and, therefore, need not be submitted to the Chief,
Quality of Water Branch, for approval. These include methods used
in support of research, experimental or developmental methods used
by a Central Laboratory, and screening methods used in the field
or in the laboratory. Data collected by these methods are not to
be stored in WATSTORE or published in the annual basic data
reports.however, the data may be published in interpretive reports
or project data reports, provided the method is fully described or
an appropriate reference is cited to provide a basis for peer
evaluation of analytical results. Defense of the validity of such
a method is, therefore, the responsibility of the individual
publishing the data.
Ordinarily, only approved methods will be used in the Central
Laboratories unless a special method is requested and concurrence
in its use is obtained from the responsible individual for
Analytical Technology Transfer in the Office of the Analytical
Services Coordinator (currently Marvin Fishman). Analysts will
not use a modification of an approved method without satisfying
all previously stated requirements for an Approved Method.
Futhermore, when a laboratory uses an alternate method to satisfy
a specific analytical request because of technical or management
considerations, the analytical method used must have been
previously shown to have equivalent or better sensitivity,
precision, and bias as compared to the method requested to the
satisfaction of the individual responsible for Analytical
Technology Transfer. If these conditions are not met, the
requester must be notified promptly and approve the change in the
method prior to analysis..
L. B. Laird
Assistant Chief Hydrologist for
Research and Technical Coordination
WRD Distribution: A, B, S, FO, PO
Key Words: analytical methods, water quality, laboratories
This memorandum supersedes Quality of Water Branch Technical
Memorandum No. 79.11.