ASTM E932-89(2021)
(Practice)Standard Practice for Describing and Measuring Performance of Dispersive Infrared Spectrometers
Standard Practice for Describing and Measuring Performance of Dispersive Infrared Spectrometers
SIGNIFICANCE AND USE
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.
1.2 This practice is not to be used as a rigorous test of performance of instrumentation.
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.5 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
Relations
Standards Content (Sample)
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: E932 − 89 (Reapproved 2021)
Standard Practice for
Describing and Measuring Performance of Dispersive
Infrared Spectrometers
This standard is issued under the fixed designation E932; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 3. Terminology
1.1 This practice covers the necessary information to
3.1 Definitions and Symbols—For definitions of terms and
qualify dispersive infrared instruments for specific analytical symbols,refertoTerminologyE131and Compilation of ASTM
applications, and especially for methods developed by ASTM
Standard Definitions.
International.
4. Significance and Use
1.2 This practice is not to be used as a rigorous test of
performance of instrumentation.
4.1 This practice is intended for all infrared spectroscopists
who are using dispersive instruments for qualitative or quan-
1.3 The values stated in SI units are to be regarded as
titative areas of analysis.
standard. No other units of measurement are included in this
standard.
4.2 The purpose of this practice is to set forth performance
1.4 This standard does not purport to address all of the
guidelines for testing instruments used in developing an
safety concerns, if any, associated with its use. It is the
analyticalmethod.Theseguidelinescanbeusedtocomparean
responsibility of the user of this standard to establish appro-
instrumentinaspecificapplicationwiththeinstrument(s)used
priate safety, health, and environmental practices and deter-
in developing the method.
mine the applicability of regulatory limitations prior to use.
4.3 An infrared procedure must include a description of the
1.5 This international standard was developed in accor-
instrumentationandoftheperformanceneededtoduplicatethe
dance with internationally recognized principles on standard-
precision and accuracy of the method.
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
5. Apparatus
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
5.1 For the purposes of this practice, dispersive instruments
include those employing prisms, gratings, or filters to separate
2. Referenced Documents
infrared radiation into its component wavelengths.
2.1 ASTM Standards:
5.2 For each new method, describe the apparatus and
E131Terminology Relating to Molecular Spectroscopy
instrumentation both physically and mechanically, and also in
E168Practices for General Techniques of Infrared Quanti-
terms of performance as taught in this practice. That is, the
tative Analysis
description should give numerical values showing the fre-
E387TestMethodforEstimatingStrayRadiantPowerRatio
quency accuracy and the frequency and the photometric
of Dispersive Spectrophotometers by the Opaque Filter
precision. State the spectral slit width maximum or slit width
Method
programifoneisused.Wherepossible,statethemaximumand
E1252Practice for General Techniques for Obtaining Infra-
minimum resolution if those data are a part of the instrument
red Spectra for Qualitative Analysis
display. Show typical component spectra as produced by the
instrument to establish the needed resolution.
This practice is under the jurisdiction ofASTM Committee E13 on Molecular
Spectroscopy and Separation Science and is the direct responsibility of Subcom-
5.3 If a computer program is used, describe the program.
mittee E13.03 on Infrared and Near Infrared Spectroscopy.
Includetheprogramminglanguageandavailability,orwhether
Current edition approved April 1, 2021. Published April 2021. Originally
the program is proprietary to a manufacturer.
approved in 1989. Last previous edition approved in 2013 as E932–89(2013).
DOI: 10.1520/E0932-89R21.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on Available fromASTM International Headquarters, 100 Barr Harbor Drive, PO
the ASTM website. Box C700, West Conshohocken, PA 19428-2959.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E932 − 89 (2021)
6. Reference to this Practice in Standards 8.4.1 Chart paper should be checked for uniformity of the
printed scale length as received and rechecked at time of use,
6.1 Reference to this practice should be included in all
particularly if the paper has been subjected to pronounced
ASTM infrared methods. The reference should appear in the
humiditychanges.Instructionsonobtainingpropermechanical
section on apparatus where the particular spectrometer is
repeatability may be given in the manufacturer’s literature.
described.
8.5 In the case of computerized dispersive instruments, any
7. Parameters in Spectroscopy
spectrum printed from a computer file must be obtained as
prescribed by the manufacturer and should be identical to the
7.1 Dispersive infrared spectrometers have a source of
original data.
quasi-monochromatic radiation together with a photometer for
measuring relative radiant power. Accurate spectrometry in-
PRECISION AND ACCURACY
volvesalargenumberofinterrelatedfactorsthatdeterminethe
quality of the radiant power passing through a sample and the 9. Definitions
sensitivity and linearity with which this radiant power can be
9.1 wavenumber precision—ameasureofthecapabilityofa
measured. Assuming proper instrumentation and its use, the
spectrometer to return to the same spectral position as mea-
instrumental factors responsible for inaccuracies in spectrom-
sured by a well-defined absorption or emission band when the
etry are resolution, linearity (Practices E168), stray radiant
instrumentisresetorrescanned.Theindexusedinthispractice
power (Test Method E387), and cell constants (Practice
is the standard deviation.
E1252). Rigorous measurement of these factors is beyond the
9.2 wavenumber accuracy—the deviation of the average
scope of this practice, and a more practical approach is
wavenumber reading of an absorption band or emission band
described for the accessible factors.
from the known wavenumber of that band.
8. Instrument Operation
10. Nature of Test
8.1 The analyst selects the proper instrumental operating
10.1 For the purpose of calibration, most methods employ
conditions in order to get satisfactory performance (1-3).
pure compounds and known mixtures at specified analytical
Because instrument design varies, the manufacturer’s recom-
wavenumbers. The wavenumbers are either read from a dial,
mendations are usually best. A record of operating conditions
optical display, chart paper, or a computer file.
should be kept so that data can be duplicated by future users.
11. Reference Wavenumbers in the Infrared Region (2)
8.2 Inadditiontooperatingconditions,thefollowingshould
11.1 The recommended wavenumber calibration points are
be checked and recorded:
the absorption maxima of a standard (98.4/0.8/0.8 by weight)
8.2.1 Ambient temperature,
indene/camphor/cyclohexanonemixturelistedinTable1.Suit-
8.2.2 Pen response time,
−1
able path lengths are 0.2 mm for the range from 3800cm to
8.2.3 Scanning speed,
−1
1580 cm and 0.03 mm for the wavenumber range from
NOTE1—Insomeinstrumentsthesefunctionsareintegratedinthescan –1 –1
1600cm to 600 cm . A mixture containing equal parts by
modes.
weight of indene, camphor, and cyclohexanone (1/1/1 by
8.2.4 Noise level, and
weight) at a path length of 0.1 mm may be used for the range
8.2.5 Mechanical repeatability. −1 −1
from 600cm to 300 cm . See Table 2 and Fig. 1.
8.3 Each of the above factors is important in the measure-
11.2 Polystyrene is also a convenient calibration standard
−1 −1
ment of analytical wavenumber and photometric data.There is
for the wavenumber range from 4000cm to 400 cm .
usually some lag between the recorded reading and the correct
Polystyrene films, approximately 0.03mm to 0.05 mm thick,
reading. Proper selection of operating conditions and good,
can be purchased from instrument manufacturers. The recom-
reproducible, sample handling techniques minimize these ef-
mended calibration peaks are listed in Fig. 2.
fects or make the effects repeatable. For example:
NOTE 3—The correction of frequency for the refractive index of air is
8.3.1 Variation in temperature of the monochromator or
significant in the wavenumber calculation only when wavelengths have
sample may cause changes in wavenumber precision and
been measured to better than 3 parts in 10000. Reference (3) tabulates
accuracy. additional reference wavenumbers of interest.
8.3.2 Scanningtoofastwilldisplacetheapparentwavenum-
11.3 For low-resolution prism or filter instruments operated
ber towards the direction scanned and will decrease the peak
in single-beam mode, the position of the atmospheric carbon
−1
absorbance reading for each band.
dioxide band near 2350 cm can be useful. This band may be
−1
resolved into a doublet. The 2350cm value is for the
NOTE 2—Some instruments provide for automatic monitoring and
approximate center between the two branches. The atmo-
correction of this effect.
−1
spheric carbon dioxide band near 667 cm is useful in the
8.4 Mechanical repeatability of the monochromator and
low-wavenumber region.
recording system as well as positioning of chart paper are
important in wavenumber measurement.
12. Dynamic Error Test
12.1 For dispersively measured spectra, the following dy-
namicerrortestissuitableforusewithmostgratingandprism
The boldface numbers in parentheses refer to a list of references at the end of
t
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