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ASTM E958-13(2021)

(Practice)

Standard Practice for Estimation of the Spectral Bandwidth of Ultraviolet-Visible Spectrophotometers

Standard Practice for Estimation of the Spectral Bandwidth of Ultraviolet-Visible Spectrophotometers

SIGNIFICANCE AND USE
4.1 These practices should be used by a person who develops an analytical method to ensure that the spectral bandwidths cited in the practice are actually the ones used.
Note 2: The method developer should establish the spectral bandwidths that can be used to obtain satisfactory results.  
4.2 These practices should be used to determine whether a spectral bandwidth specified in a method can be realized with a given spectrophotometer and thus whether the instrument is suitable for use in this application. If accurate absorbance measurements are to be made on compounds with sharp absorption bands (natural half band widths of less than 15 nm) the spectral bandwidth of the spectrometer used should be better than 1/8th of the natural half band width of the compound’s absorption.  
4.3 These practices allow the user of a spectrophotometer to estimate the actual spectral bandwidth of the instrument under a given set of conditions and to compare the result to the spectral bandwidth calculated from data given in the manufacturer's literature or indicated by the instrument.
SCOPE
1.1 This practice describes procedures for estimating the spectral bandwidth of a spectrophotometer in the wavelength region of 185 nm to 820 nm.  
1.2 These practices are applicable to all modern spectrophotometer designs utilizing computer control and data handling. This includes conventional optical designs, where the sample is irradiated by monochromatic light, and ‘reverse’ optic designs coupled to photodiode arrays, where the light is separated by a polychromator after passing through the sample. For spectrophotometers that utilize servo-operated slits and maintain a constant period and a constant signal-to-noise ratio as the wavelength is automatically scanned, and/or utilize fixed slits and maintain a constant servo loop gain by automatically varying gain or dynode voltage, refer to the procedure described in Annex A1. This procedure is identical to that described in earlier versions of this practice.  
1.3 This practice does not cover the measurement of limiting spectral bandwidth, defined as the minimum spectral bandwidth achievable under optimum experimental conditions.  
1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.5 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.6 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

Status
Published
Publication Date
31-Mar-2021
ICS
17.180.30 - Optical measuring instruments
Technical Committee
E13 - Molecular Spectroscopy and Separation Science
Drafting Committee
E13.01 - Ultra-Violet, Visible, and Luminescence Spectroscopy
Current Stage
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ASTM E958-13(2021) - Standard Practice for Estimation of the Spectral Bandwidth of Ultraviolet-Visible SpectrophotometersASTM E958-13(2021) - Standard Practice for Estimation of the Spectral Bandwidth of Ultraviolet-Visible Spectrophotometers
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ASTM E958-13(2021) - Standard Practice for Estimation of the Spectral Bandwidth of Ultraviolet-Visible Spectrophotometers
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This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: E958 − 13 (Reapproved 2021)
Standard Practice for
Estimation of the Spectral Bandwidth of Ultraviolet-Visible
1
Spectrophotometers
This standard is issued under the fixed designation E958; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Terminology
1.1 This practice describes procedures for estimating the 2.1 Definitions:
spectral bandwidth of a spectrophotometer in the wavelength
2.1.1 spectral bandwidth, n—the wavelength interval of
region of 185 nm to 820 nm.
radiation leaving the exit slit of a monochromator measured at
half the peak detected radiant power.
1.2 These practices are applicable to all modern spectropho-
tometer designs utilizing computer control and data handling.
3. Summary of Practice
Thisincludesconventionalopticaldesigns,wherethesampleis
irradiated by monochromatic light, and ‘reverse’optic designs
3.1 The following test procedures are written for all spec-
coupled to photodiode arrays, where the light is separated by a
trophotometer designs that have provision for recording (that
polychromator after passing through the sample. For spectro-
is, collecting and storing) spectral data digitally. Processing
photometers that utilize servo-operated slits and maintain a
may be by built-in programs or in a separate computer. Data
constant period and a constant signal-to-noise ratio as the
may be collected in either the transmittance or the absorbance
wavelength is automatically scanned, and/or utilize fixed slits
mode, although for the Liquid Ratio procedure, the peak and
and maintain a constant servo loop gain by automatically
trough values must be measured in absorbance.
varying gain or dynode voltage, refer to the procedure de-
3.2 Line Emission Source Procedure—The continuum
scribed in Annex A1. This procedure is identical to that
source is replaced with a line emission source, such as a
described in earlier versions of this practice.
mercury lamp, and the apparent half-intensity bandwidth of an
1.3 This practice does not cover the measurement of limit-
emission line occurring in the wavelength region of interest is
ing spectral bandwidth, defined as the minimum spectral
measured using the slit width, or indicated spectral bandwidth
bandwidth achievable under optimum experimental conditions.
required to be estimated. This procedure can be used for
1.4 The values stated in SI units are to be regarded as instrumentation having spectral bandwidths in the range
0.1 nm to 10 nm.
standard. No other units of measurement are included in this
standard.
NOTE 1—In photodiode array instrumentation, the array spacing be-
1.5 This standard does not purport to address all of the tween the diode elements may invalidate this procedure.
safety concerns, if any, associated with its use. It is the
3.3 Liquid Ratio Procedure—The calculated spectral peak
responsibility of the user of this standard to establish appro-
to trough ratio of a defined small percentage of toluene in
priate safety, health, and environmental practices and deter-
hexane will vary with the spectral bandwidth of the spectro-
mine the applicability of regulatory limitations prior to use.
photometer when scanned in the UV region. This procedure
1.6 This international standard was developed in accor-
can be used for all instrumentation having spectral bandwidths
dance with internationally recognized principles on standard-
in the range 0.5 nm to 3.0 nm.
ization established in the Decision on Principles for the
3.4 Benzene Vapor Procedure—The characteristics of a
Development of International Standards, Guides and Recom-
spectrum of benzene vapor in the UV region will vary
mendations issued by the World Trade Organization Technical
significantlywiththespectralbandwidthofthespectrophotom-
Barriers to Trade (TBT) Committee.
eter. This procedure can be used for instrumentation having
spectral bandwidths in the range 0.1 nm to 0.5 nm.
1
This practice is under the jurisdiction of ASTM Committee E13 on Molecular
4. Significance and Use
Spectroscopy and Separation Science and is the direct responsibility of Subcom-
mittee E13.01 on Ultra-Violet, Visible, and Luminescence Spectroscopy.
4.1 These practices should be used by a person who
Current edition approved April 1, 2021. Published April 2021. Originally
develops an analytical method to ensure that the spectral
approved in 1983. Last previous edition approved in 2013 as E958 – 13. DOI:
10.1520/E0958-13R21. bandwidths
...

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SCOPE
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SIGNIFICANCE AND USE
5.1 Stray radiant power can be a significant source of error in spectrophotometric measurements. SRP usually increases with the passage of time; therefore, testing should be performed periodically. Moreover, the SRPR test is an excellent indicator of the overall condition of a spectrophotometer. A control-chart record of the results of routinely performed SRPR tests can be a useful indicator of need for corrective action or, at least, of the changing reliability of critical measurements.  
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Standard Practice for Describing and Measuring Performance of Ultraviolet and Visible Spectrophotometers

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4.1 This practice permits an analyst to compare the general performance of an instrument on any given day with the prior performance of an instrument. This practice is not necessarily meant for comparison of different instruments with each other even if the instruments are of the same type and model. This practice is not meant for comparison of the performance of one instrument operated under differing conditions.
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1.1 This practice describes two levels of tests to measure the performance of laboratory Fourier transform mid-infrared (FT-MIR) spectrometers equipped with a standard sample holder used for transmission measurements.  
1.2 This practice is not directly applicable to Fourier transform infrared (FT-IR) spectrometers equipped with various specialized sampling accessories such as flow cells or reflectance optics, nor to Fourier transform near-infrared (FT-NIR) spectrometers, nor to FT-IR spectrometers run in step scan mode.  
1.2.1 If the specialized sampling accessory can be removed and replaced with a standard transmission sample holder, then this practice can be used. However, the user should recognize that the performance measured may not reflect that which is achieved when the specialized accessory is in use.  
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1.3.1 Exception—Informational inch-pound units are provided in 5.4.  
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Standard Practice for Describing and Measuring Performance of Dispersive Infrared Spectrometers

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4.1 This practice is intended for all infrared spectroscopists who are using dispersive instruments for qualitative or quantitative areas of analysis.  
4.2 The purpose of this practice is to set forth performance guidelines for testing instruments used in developing an analytical method. These guidelines can be used to compare an instrument in a specific application with the instrument(s) used in developing the method.  
4.3 An infrared procedure must include a description of the instrumentation and of the performance needed to duplicate the precision and accuracy of the method.
SCOPE
1.1 This practice covers the necessary information to qualify dispersive infrared instruments for specific analytical applications, and especially for methods developed by ASTM International.  
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3.1 The range of concentration of a fluorescing substance in solution over which the fluorescence varies linearly with the concentration is the range most useful for quantitative analysis. This range is affected by properties of the solution under analysis and by features of the measuring system. This test method provides a means of testing the performance of a fluorescence measuring system and of determining the concentration range over which the system is suitable for making a given quantitative analysis.  
3.2 This test method is not meant for comparing the performance of different fluorescence measuring instruments.
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1.1 This test method covers a procedure for evaluating the limits of the linearity of response with fluorescence intensity of fluorescence-measuring systems under operating conditions. Particular attention is given to slit widths, filters, and sample containers. This test method can be used to test the overall linearity under a wide variety of instrumental and sampling conditions. The results obtained apply only to the tested combination of slit width and filters, and the size, type and illumination of the sample cuvette, all of which must be stated in the report. The sources of nonlinearity may be the measuring electronics, excessive absorption of either the exciting or emitted radiation, or both, and the sample handling technique, particularly at low concentrations.  
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SCOPE
1.1 This practice is intended as a guide for the use of a flame photometric detector (FPD) as the detection component of a gas chromatographic system.  
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