Guideline for Industry
Text on Validation of
Analytical Procedures
ICH-Q2A
 March 1995 TABLE OF CONTENTS
I. INTRODUCTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
II. TYPES OF ANALYTICAL PROCEDURES TO BE VALIDATED . . . . . . . . 2
GLOSSARY  .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .  APPENDIX A
1. Analytical Procedure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1
2. Specificity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1
3. Accuracy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-1
4. Precision . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-2
a. Repeatability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-2
b. Intermediate Precision . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-2
c. Reproducibility . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-2
5. Detection Limit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-2
6. Quantitation Limit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-2
7. Linearity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-3
8. Range . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-3
9. Robustness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A-3
i GUIDELINE FOR INDUSTRY 1
TEXT ON VALIDATION OF ANALYTICAL PROCEDURES
I. INTRODUCTION
This document presents a discussion of the characteristics for consideration
during the validation of the analytical procedures included as part of registration
applications submitted within the European Union, Japan and the United States. 
This document does not necessarily seek to cover the testing that may be
required for registration in, or export to, other areas of the world.  Furthermore,
this text presentation serves as a collection of terms, and their definitions, and is
not intended to provide direction on how to accomplish validation.  These terms
and definitions are meant to bridge the differences that often exist between
various compendia and regulators of the European Union, Japan and the United
States.
The objective of validation of an analytical procedure is to demonstrate that it is
suitable for its intended purpose.  A tabular summation of the characteristics
applicable to identification, control of impurities and assay procedures is
included.  Other analytical procedures may be considered in future additions to
1This guideline was developed within the Expert Working Group (Quality) of the
International Conference on Harmonisation of Technical Requirements for Registration
of Pharmaceuticals for Human Use (ICH) and has been subject to consultation by the
regulatory parties, in accordance with the ICH process.  This document has been
endorsed by the ICH Steering Committee at  Step 4 of the ICH process, October 27,
1994.  At Step 4 of the process, the final draft is recommended for adoption to the
regulatory bodies of the European Union, Japan and the USA.  This guideline was
published in the Federal Register on March 1, 1995 (60 FR 11260) and is applicable to
drug and biological products.  In the past, guidelines have generally been issued under
 10.90(b) [21 CFR 10.90(b)], which provides for the use of guidelines to state
procedures or standards of general applicability that are not legal requirements but that
are acceptable to FDA.  The agency is now in the process of revising 10.90(b). 
Therefore, this guideline is not being issued under the authority of 10.90(b), and it
does not create or confer any rights, privileges or benefits for or on any person, nor
does it operate to bind FDA in any way.  For additional copies of this guideline contact
the Consumer Affairs Branch (formerly the Executive Secretariat Staff), HFD-210,
Center for Drug Evaluation and Research, 7500 Standish Place, Rockville, MD, 20855,
301-594-1012.  An electronic version of this guideline is also available via Internet by
connecting to the CDER file transfer protocol (FTP) server (CDVS2.CDER.FDA.GOV). this document.
II. TYPES OF ANALYTICAL PROCEDURES TO BE VALIDATED
The discussion of the validation of analytical procedures is directed to the four
most common types of analytical procedures:
Identification tests.
Quantitative tests for impurities' content.
Limit tests for the control of impurities.
Quantitative tests of the active moiety in samples of drug substance or
drug product or other selected component(s) in the drug product.
Although there are many other analytical procedures, such as dissolution testing
for drug products or particle size determination for drug substance, these have
not been addressed in the initial text on validation of analytical procedures. 
Validation of these additional analytical procedures is equally important to those
listed herein and may be addressed in subsequent documents.
A brief description of the types of tests considered in this document is provided
below.
Identification tests are intended to ensure the identity of an analyte in a
sample.  This is normally achieved by comparison of a property of the
sample (e.g., spectrum, chromatographic behavior, chemical reactivity,
etc.) to that of a reference standard.
Testing for impurities can be either a quantitative test or a limit test for the
impurity in a sample.  Either test is intended to accurately reflect the
purity characteristics of the sample.  Different validation characteristics
are required for a quantitative test than for a limit test.
Assay procedures are intended to measure the analyte present in a given
sample.  In the context of this document, the assay represents a
quantitative measurement of the major component(s) in the drug
substance.  For the drug product, similar validation characteristics also
apply when assaying for the active or other selected component(s).  The
same validation characteristics may also apply to assays associated with
other analytical procedures (e.g., dissolution).
2 The objective of the analytical procedure should be clearly understood since this
will govern the validation characteristics which need to be evaluated.  Typical
validation characteristics which should be considered are listed below:
Accuracy
Precision
Repeatability
Intermediate Precision
Specificity
Detection Limit 
Quantitation Limit 
Linearity 
Range
Each of these validation characteristics is defined in the attached Glossary.  The
table lists those validation characteristics regarded as the most important for the
validation of different types of analytical procedures.  This list should be
considered typical for the analytical procedures cited but occasional exceptions
should be dealt with on a case-by-case basis.  It should be noted that
robustness is not listed in the table but should be considered at an appropriate
stage in the development of the analytical procedure.
Furthermore revalidation may be necessary in the following circumstances: 
Changes in the synthesis of the drug substance; 
Changes in the composition of the finished product; 
Changes in the analytical procedure;
The degree of revalidation required depends on the nature of the changes. 
Certain other changes may require validation as well.
3 TABLE
TYPE OF IDENTIFICATIO TESTING FOR ASSAY;
ANALYTICAL N IMPURITIES dissolution
PROCEDURE; (measurement
CHARACTERISTICS only);
content/potenc
Quantitation Limit
y
Accuracy - + - +
Precision
Repeatability - + - +
Intermediate    
Precision - +1 - +1
Specificity2 + + + +
Detection Limit - -3 + -
Quantitation Limit - + - -
Linearity - + - +
Range - + - +
NOTE: -  signifies that this characteristic is not normally evaluated; + signifies that this characteristic is normally evaluated.
1 In cases where reproducibility (see Glossary) has been performed, intermediate precision is not needed.
2 Lack of specificity of one analytical procedure could be compensated by other supporting analytical procedure(s).
3 May be needed in some cases.
4 Appendix A
GLOSSARY
1. ANALYTICAL PROCEDURE
The analytical procedure refers to the way of performing the analysis.  It should
describe in detail the steps necessary to perform each analytical test.  This may
include but is not limited to:  the sample, the reference standard and the
reagents preparations, use of the apparatus, generation of the calibration curve,
use of the formulae for the calculation, etc.
2. SPECIFICITY
Specificity is the ability to assess unequivocally the analyte in the presence of
components which may be expected to be present.  Typically these might
include impurities, degradants, matrix, etc.
Lack of specificity of an individual analytical procedure may be compensated by
other supporting analytical procedure(s).
This definition has the following implications:
Identification:  To ensure the identity of an analyte.
Purity Tests: To ensure that all the analytical procedures performed allow an
accurate statement of the content of impurities of an analyte, i.e.,
related substances test, heavy metals, residual solvents content,
etc.
Assay (content or potency):
To provide an exact result which allows an accurate
statement on the content or potency of the analyte in a
sample.
3. ACCURACY
The accuracy of an analytical procedure expresses the closeness of agreement
between the value which is accepted either as a conventional true value or an
accepted reference value and the value found.
This is sometimes termed trueness.
A-1 4. PRECISION
The precision of an analytical procedure expresses the closeness of agreement
(degree of scatter) between a series of measurements obtained from multiple
sampling of the same homogeneous sample under the prescribed conditions. 
Precision may be considered at three levels: repeatability, intermediate
precision and reproducibility.
Precision should be investigated using homogeneous, authentic samples. 
However, if it is not possible to obtain a homogeneous sample it may be
investigated using artificially prepared samples or a sample solution.
The precision of an analytical procedure is usually expressed as the variance,
standard deviation or coefficient of variation of a series of measurements.
a. Repeatability
Repeatability expresses the precision under the same operating
conditions over a short interval of time.  Repeatability is also termed
intra-assay precision 
b. Intermediate precision
Intermediate precision expresses within laboratories variations:  different
days different analysts, different equipment, etc.
c. Reproducibility
Reproducibility expresses the precision between laboratories
(collaborative studies usually applied to standardization of methodology).
5. DETECTION LIMIT
The detection limit of an individual analytical procedure is the lowest amount of
analyte in a sample which can be detected but not necessarily quantitated as an
exact value.
6. QUANTITATION LIMIT
The quantitation limit of an individual analytical procedure is the lowest amount
of analyte in a sample which can be quantitatively determined with suitable
precision and accuracy.  The quantitation limit is a parameter of quantitative
assays for low levels of compounds in sample matrices, and is used particularly
A-2 for the determination of impurities and/or degradation products.
7. LINEARITY
The linearity of an analytical procedure is its ability (within a given range) to
obtain test results which are directly proportional to the concentration (amount)
of analyte in the sample.
8. RANGE
The range of an analytical procedure is the interval between the upper and lower
concentration (amounts) of analyte in the sample (including these
concentrations) for which it has been demonstrated that the analytical procedure
has a suitable level of precision, accuracy and linearity.
9. ROBUSTNESS
The robustness of an analytical procedure is a measure of its capacity to remain
unaffected by small, but deliberate variations in method parameters and
provides an indication of its reliability during normal usage.
A-3