ASTM E925-83(1994)e1

Standard Practice for Monitoring the Calibration of Ultraviolet-Visible Spectrophotometers whose Spectral Slit Width does not Exceed 2 nm

SCOPE
1.1 This practice covers the parameters of spectrophotometric performance that are critical for testing the adequacy of instrumentation for most routine tests and methods 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.
1.2 This practice may be used as a significant test of the performance of instruments for which the spectral slit width 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 x 10-4 yields
1.3 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 energy source.
1.4 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.

General Information

• Status: Historical
• Publication Date: 09-Mar-2002
• ICS: 17.180.30 - Optical measuring instruments
• ICS: 71.040.50 - Physicochemical methods of analysis
• Technical Committee: E13 - Molecular Spectroscopy and Separation Science
• Drafting Committee: E13.01 - Ultra-Violet, Visible, and Luminescence Spectroscopy

Relations

• Replaced By: ASTM E925-02 - Standard Practice for Monitoring the Calibration of Ultraviolet-Visible Spectrophotometers whose Spectral Slit Width does not Exceed 2 nm
• Effective Date: 10-Mar-2002
• Referred By: ASTM E2056-04(2016) - Standard Practice for Qualifying Spectrometers and Spectrophotometers for Use in Multivariate Analyses, Calibrated Using Surrogate Mixtures
• Effective Date: 10-Mar-2002
• Referred By: ASTM D8470-22 - Standard Practice for Development and Implementation of Instrument Performance Tests for Use on Multivariate Online, At-Line and Laboratory Spectroscopic Based Analyzer Systems
• Effective Date: 10-Mar-2002
• Referred By: ASTM E1341-16(2020) - Standard Practice for Obtaining Spectroradiometric Data from Radiant Sources for Colorimetry
• Effective Date: 10-Mar-2002
• Referred By: ASTM ISO/ASTM51205-17 - Standard Practice for Use of a Ceric-Cerous Sulfate Dosimetry System
• Effective Date: 10-Mar-2002
• Referred By: ASTM ISO/ASTM51538-17 - Standard Practice for Use of the Ethanol-Chlorobenzene Dosimetry System
• Effective Date: 10-Mar-2002
• Referred By: ASTM E1866-97(2021) - Standard Guide for Establishing Spectrophotometer Performance Tests
• Effective Date: 10-Mar-2002
• Referred By: ASTM E169-16(2022) - Standard Practices for General Techniques of Ultraviolet-Visible Quantitative Analysis
• Effective Date: 10-Mar-2002
• Referred By: ASTM ISO/ASTM51310-22 - Standard Practice for Use of a Radiochromic Optical Waveguide Dosimetry System
• Effective Date: 10-Mar-2002
• Referred By: ASTM ISO/ASTM51401-13 - Standard Practice for Use of a Dichromate Dosimetry System
• Effective Date: 10-Mar-2002
• Referred By: ASTM E2153-01(2023) - Standard Practice for Obtaining Bispectral Photometric Data for Evaluation of Fluorescent Color
• Effective Date: 10-Mar-2002
• Referred By: ASTM D5831-17 - Standard Practice for Screening Fuels in Soils
• Effective Date: 10-Mar-2002
• Referred By: ASTM ISO/ASTM51026-15 - Standard Practice for Using the Fricke Dosimetry System
• Effective Date: 10-Mar-2002
• Referred By: ASTM G178-16(2023) - Standard Practice for Determining the Activation Spectrum of a Material (Wavelength Sensitivity to an Exposure Source) Using the Sharp Cut-On Filter or Spectrographic Technique
• Effective Date: 10-Mar-2002
• Referred By: ASTM E1164-12(2023)e1 - Standard Practice for Obtaining Spectrometric Data for Object-Color Evaluation
• Effective Date: 10-Mar-2002

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
e1
Designation: E 925 – 83 (Reapproved 1994)
Standard Practice for
the Periodic Calibration of Narrow Band-Pass
Spectrophotometers
This standard is issued under the fixed designation E 925; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
e NOTE—Section 11 was added editorially in June 1994.
INTRODUCTION
In the application of spectrophotometric methods of analysis it is the responsibility of the analyst
to verify and validate that the instrument is functioning properly and is capable of providing
acceptable analytical results. It is preferable that the verification of instrument performance be
accomplished through the use of readily available, stable reference materials whose properties have
been accurately measured by a standardizing laboratory. Several such certified standards are currently
available from the National Bureau of Standards and their use in the tests and measurements described
in this practice is satisfactory for evaluating the performance of spectrophotometers.
This practice covers some of the essential instrumental parameters that should be evaluated to
ensure the acceptability of the analytical data routinely obtained on the instrument. These parameters
include the accuracy of the wavelength and absorbance scales and stray radiant power levels.
The accuracy of the wavelength scale in both the UV and VIS regions is determined using the sharp
absorption bands of a holmium oxide glass filter. The wavelength of maximum absorbance of these
bands has been determined. The accuracy of the absorbance scale is determined using certified
standards available through the National Bureau of Standards. The absorbance scale accuracy in the
UV region (235–350 nm) is determined using acidic solutions of potassium dichromate (solid
potassium dichromate is available from the National Bureau of Standards as SRM 935) while in the
visible region (440–635 nm) the absorbance accuracy is determined using three glass filters (National
Bureau of Standards SRM 930 series). The use of these reference materials provides a valid and
relatively simple means to test the accuracy of the wavelength and absorbance scales of narrow
band-pass spectrophotometers in the spectral ranges indicated.
1. Scope performance of instrumentation. While this procedure is not
designed to extensively evaluate the performance of an instru-
1.1 This practice covers the parameters of spectrophotomet-
ment, it may be used to verify quantitative performance on an
ric performance that are critical for testing the adequacy of
ongoing basis and to compare one instrument’s performance
instrumentation for most routine tests and methods. The
with that of other units.
recommended tests provide a measurement of the important
1.3 This practice should be performed on a periodic basis,
parameters controlling results in spectrophotometric methods,
the frequency of which depends on the physical environment
but it is specifically not to be inferred that all factors in
within which the instrumentation is used. Thus, units handled
instrument performance are measured.
roughly or used under adverse conditions (exposed to dust,
1.2 This practice may be used as a significant test of the
chemical vapors, vibrations, or combinations thereof) should
be calibrated more frequently than those not exposed to such
This practice is under the jurisdiction of ASTM Committee E-13 on Molecular
conditions. This practice should also be performed after any
Spectroscopy and is the direct responsibility of Subcommittee E13.01 on Ultraviolet
significant repairs are made on a unit, such as those involving
and Visible Spectroscopy.
the optics, detector or radiant energy source.
Current edition approved Feb. 25, 1983. Published July 1983.
Available from Beckman Instruments (Part No. 96157) and from distributors 1.4 This standard does not purport to address all of the
from Corning Glass Works (Catalogue No. 3131).
safety concerns, if any, associated with its use. It is the
McNeirney, J., and Slavin, W., Applied Optics, Vol 1, 1962, p. 365.
responsibility of the user of this standard to establish appro-
SRM 935 and 930 may be purchased from the Office of Standard Reference
priate safety and health practices and determine the applica-
Materials, National Bureau of Standards, Washington, D. C. 20234.
Routine tests are defined as those in which absorbance data obtained on a
bility of regulatory limitations prior to use.
sample are compared to those of a standard sample preparation.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
E 925
2. Referenced Documents 7. Determination of Wavelength Accuracy in the
Ultraviolet and Visible Spectral Regions
2.1 ASTM Standards:
E 131 Terminology Relating to Molecular Spectroscopy
7.1 Discussion—The holmium oxide glass filter is used for
E 169 Practices for General Techniques of Ultraviolet/ evaluating wavelength accuracy. The wavelengths (nm) moni-
Visible Quantitative Analysis
tored are:
E 275 Practice for Describing and Measuring Performance 279.4
of Ultraviolet, Visible, and Near Infrared Spectrophotom-
287.5
eters 360.9
2.2 Other Publication:
418.7
NBS Special Publication 260-54: Certification and Use of 453.2
Acidic Potassium Dichromate Solutions As An Ultraviolet
536.2
Absorbance Standard 637.5
NOTE 1—Depending on the base glass of the filter, a peak at 241.5 nm
3. Terminology
may also be used for calibration purposes.
3.1 Definitions:
7.1.1 If the wavelength scale is found to be less accurate
3.1.1 For the definitions of terms used in this practice, refer
than the tolerance stated in the instrument manufacturer’s
to Terminology E 131.
specifications, or if the observed absorption bands of the
3.1.2 For a description of the instrumental parameters
holmium oxide glass deviate by more than 61 nm from the
evaluated in this practice, refer to Practice E 275.
values stated above (see Note 2) then corrective service must
3.1.3 For a description of quantitative ultraviolet spectro-
by performed on the instrument by a qualified service person.
photometric techniques, refer to Practice E 169.
If the user performs this service himself, he should carefully
follow the manufacturer’s recommended procedure.
4. Significance and Use
4.1 This practice permits an analyst to compare the perfor- NOTE 2—The larger of these tolerance values should be used as the
criterion of instrumental wavelength accuracy at each wavelength
mance of an instrument to the manufacturer’s supplied perfor-
checked.
mance specifications and to verify its suitability for continued
routine use. It also provides generation of calibration data on a
7.1.2 The wavelength accuracy is dependent on the spectral
periodic basis, forming a base from which any changes in the
bandwidth and thus on the slit width. Spectral bandwidths may
performance of the instrument will be evident.
be determined from the manufacturer’s specifications.
7.2 Procedure:
5. Reference to this Calibration Procedure
7.2.1 Examine the holmium oxide filter and remove any
5.1 Reference to this practice in any spectrophotometric surface contamination using a soft brush or lens paper. Mea-
calibration scheme shall constitute due notification that the
sure the temperature of the sample compartment by placing a
adequacy of the spectrophotometer performance has been thermometer into the cell compartment of a stabilized instru-
evaluated by means of this practice. Performance is considered
ment and replacing the compartment cover securely. Place the
to be adequate when the calibration data obtained are in thermometer bulb as close to the actual position that will be
agreement with the true values.
occupied by the standard. After a suitable period of time record
the temperature reading, remove the thermometer, and resume
6. Instrument Operation
normal operations.
7.2.2 Record the blank absorbance (air versus air) readings
6.1 In obtaining spectrophotometric calibration data the
at the appropriate wavelength intervals and scan speeds and
analyst must select the proper instrumental operating condi-
perform any necessary baseline adjustments. Record the wave-
tions to realize satisfactory instrument performance. Operating
length of maximum absorbance as a function of wavelength at
conditions for individual instruments are best obtained from
each appropriate wavelength interval and scan speed. If large
the manufacturer’s literature because of variations in instru-
discrepancies (>1 nm) exist between the true and measured
ment design.
wavelengths, repeat the procedure at a slower scan speed and
6.2 When using calibration standards, all the components of
narrower slit width if possible to verify the nonconformity.
the spectrophotometer must be functioning properly. In addi-
7.2.3 Report the wavelength calibration data in Table 1.
tion, the temperature of the specimen compartment should be
between 23° and 30°C. Matched solution cells should be used
8. Evaluation of Stray Radiant Power Ratio (SRPR)
for calibration purposes.
6.3 Each of the above factors in instrument operation is
8.1 Discussion—A portion of the unwanted stray radiant
important in the determination of wavelength and absorbance
power detected by the photodetector can be measured using the
accuracy.
following sharp cut-off solution filters in 1-cm cells:
Solution Wavelength
KI, 1.0 g/L in H O 220 nm
K Cr O , 0.25 g/L in aqueous 370 nm
2 2 7
Annual Book of ASTM Standards, Vol 03.06.
0.05 N KOH
Available from the National Technical Information Service, Port Royal Road,
Springfield, VA 22161. 8.1.1 Reagent grade materials should be used for these
E 925
TABLE 1 UV-VIS Spectrophotometers Wavelength and Stray
National Bureau of Standards. The absorbance scale accuracy
Radiant Power Ratio Calibration
in the ultraviolet region (235 to 350 nm) is determined using
Instrument __________
acidic solutions of potassium dichromate (National Bureau of
Date ______________
Standards SRM 935) while in the visible region (440 to 635
Temperature ________
Analyst ____________
nm) the absorbance accuracy is determined using three essen-
Wavelength Calibration: Holmium Oxide Filter
tially neutral density glass filters (National Bureau of Standards
Ob- Wavelength Toler-
SRM 930 series).
True served ance
Scan A
Wavelength Wave- Does 9.1.1 If the measured absorbances ( measured) of the stan-
Speed Con-
(nm) Range length Not
dards are outside the acceptable range, then corrective service
forms
(nm) Conform
must be performed on the instrument by a qualified service
278.4–280.4
286.5–288.5 person. If the user performs this service himself, then he should
359.
...