This practice covers the parameters of spectrophotometric
performance that are critical for testing the adequacy of
instrumentation for most routine tests and methods2
within the wavelength range of 200 to 700 nm and the absorbance
range of 0 to 2. The recommended tests provide a measurement of the
important parameters controlling results in spectrophotometric
methods, but it is specifically not to be inferred that all factors
in instrument performance are measured.
This practice may be used as a significant test of the
performance of instruments for which the spectral bandwidth does
not exceed 2 nm and for which the manufacturer's specifications for
wavelength and absorbance accuracy do not exceed the performance
tolerances employed here. This practice employs an illustrative
tolerance of + 1% relative for the error of the
absorbance scale over the range of 0.2 to 2.0, and of +1.0
nm for the error of the wavelength scale. A suggested maximum stray
radiant power ratio of 4 × 10-4 yields <1 %
absorbance bias at an absorbance of 2. These tolerances are chosen
to be compatible with many chemical applications while comfortably
exceeding the uncertainty of the certified values for the reference
materials and typical manufacturer's specifications for error in
the wavelength and absorbance scales of the instrument under test.
The user is encouraged to develop and use tolerance values more
appropriate to the requirements of the end use application. This
procedure is designed to verify quantitative performance on an
ongoing basis and to compare one instrument's performance with that
of other similar units. Refer to Practice E275 to extensively
evaluate the performance of an instrument.
This practice should be performed on a periodic basis, the
frequency of which depends on the physical environment within which
the instrumentation is used. Thus, units handled roughly or used
under adverse conditions (exposed to dust, chemical vapors,
vibrations, or combinations thereof) should be tested more
frequently than those not exposed to such conditions. This practice
should also be performed after any significant repairs are made on
a unit, such as those involving the optics, detector, or radiant
The values stated in SI units are to be regarded as standard. No
other units of measurement are included in this standard.
This standard does not purport to address all of the safety
concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and
health practices and determine the applicability of regulatory
limitations prior to use.
2 Routine tests are defined as those in which
absorbance data obtained on a sample are compared to those of a
standard sample preparation.
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