ASTM E169-99
(Practice)Standard Practices for General Techniques of Ultraviolet-Visible Quantitative Analysis
Standard Practices for General Techniques of Ultraviolet-Visible Quantitative Analysis
SCOPE
1.1 These practices are intended to provide general information on the techniques most often used in ultraviolet and visible quantitative analysis. The purpose is to render unnecessary the repetition of these descriptions of techniques in individual methods for quantitative analysis.
1.2 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of whoever uses this standard to consult and establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation:E169–99
Standard Practices for
General Techniques of Ultraviolet-Visible
1
Quantitative Analysis
This standard is issued under the fixed designation E 169; 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.
1. Scope When applied to a mixture of n noninteracting components,
it may be expressed as follows:
1.1 These practices are intended to provide general infor-
mation on the techniques most often used in ultraviolet and A 5a bc 1a bc 1 . 1a bc (2)
1 1 2 2 n n
visible quantitative analysis. The purpose is to render unnec-
essary the repetition of these descriptions of techniques in
NOTE 1—Detailed discussion of the origin and validity of Beer’s law
individual methods for quantitative analysis.
maybefoundinthebooksandarticleslistedinthebibliographyattheend
1.2 This standard does not purport to address all of the of these practices.
safety concerns, if any, associated with its use. It is the
3.2 This practice describes the application of Beer’s law in
responsibility of the user of this standard to establish appro-
typical spectrophotometric analytical applications. It also de-
priate safety and health practices and determine the applica-
scribes operating parameters that must be considered when
bility of regulatory limitations prior to use.
using these techniques.
2. Referenced Documents
4. Significance and Use
2.1 ASTM Standards:
4.1 These practices are a source of general information on
2
E 131 Terminology Relating to Molecular Spectroscopy
the techniques of ultraviolet and visible quantitative analyses.
E 168 Practices for General Techniques of Infrared Quanti-
Theyprovidetheuserwithbackgroundinformationthatshould
2
tative Analysis
help ensure the reliability of spectrophotometric measure-
E 275 Practice for Describing and Measuring the Perfor-
ments.
mance of Ultraviolet, Visible, and Near-Infrared Spectro-
4.2 These practices are not intended as a substitute for a
2
photometers
thorough understanding of any particular analytical method. It
E 925 Practice for Periodic Calibration of Narrow Band-
is the responsibility of the user to familiarize him or herself
2
Pass Spectrophotometers
with the critical details of a method and the proper operation of
E 958 Practice for Measuring Practical Spectral Bandwidth
the available instrumentation.
2
of Ultraviolet-Visible Spectrophotometers
5. Sample Preparation
3. Summary of Practice
5.1 Accurately weigh the specified amount of the sample
3.1 Quantitative ultraviolet and visible analyses are based
(solid or liquid). Dissolve in the appropriate solvent and dilute
upontheabsorptionlaw,knownasBeer’slaw.Theunitsofthis
to the specified volume in volumetric glassware of the required
law are defined in Terminology E 131. Beer’s law (Note 1)
accuracy. (Solvent and flask should be approximately the same
holds at a single wavelength and when applied to a single
temperature as the spectrophotometer). If needed, a dilution
component sample it may be expressed in the following form
should be made with a calibrated pipet and volumetric flask,
(see Section 10):
using adequate volumes for accuracy. Fill the absorption cell
A 5abc (1)
with the solution, and fill the comparison or blank cell with the
pure solvent.
6. Cell and Base-Line Checks
1
6.1 Clean and match the cells. Suggested cleaning proce-
These practices are under the jurisdiction of ASTM Committee E-13 on
MolecularSpectroscopyandarethedirectresponsibilityofSubcommitteeE13.01on
dures are presented in Practice E 275.
Ultraviolet and Visible Spectroscopy.
6.2 Establish the base-line of a recording double-beam
Current edition approved Feb. 10, 1999. Published July 1999. Originally
spectrophotometer by scanning over the appropriate wave-
published as E 169 – 60 T. Last previous edition E 169 – 93.
2
Annual Book of ASTM Standards, Vol 03.06. length region with pure solvent in both cells. Determine
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E169
apparent absorbance of the sample cell at each wavelength of 8.2 Iftheanalyticalmethodspecifiesamechanicalslitwidth
interest. These absorbances are cell corrections that are sub- for a particular type of instrument and the same type of
tracted from the absorbance of the sample solution at the instrument is being used, set the slit width to the specified
corresponding wavelengths. values. If a different type of instrument is being used and
6.3 Forsinglebeaminstruments,eitherusethesamecellfor information is available from which the spectral slit
...
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