Equilibrium Constants from Spectrophotometric Data
The Windows™ application HypSpec2014 is to
be used for for the determination of equilibrium constants from spectrophotometric
data. See HypSpec for details of the previous version.
IHypSpec2014 can process UV/visible, circular dichroism, infrared, Raman, luminescence
and fluorescence data, subject to the single requirement that the spectral intensity
of each chemical species should be proportional to the concentration of that
species in solution. The spectral data may be obtained by titration or from
a set of individual solutions (batch data). There is an option to include pH
measurements in addition with both titration and batch data. For only potentiometric
data use Hyperquad2013.
These references to precursor programs give the basic principles, but they
are somewhat out of date as the algorithms have been changed extensively.
Hyperquad: P. Gans, A. Sabatini and A. Vacca, Talanta,
(1996), 43, 1739-1753.
pHab: P. Gans, A. Sabatini and A. Vacca,, Annali di Chimica,
(1999), 89, 45-49.
- Model definition. There are no restrictions on the number or nature of reagents
or complex species formed from them
- Import experimental data from instrumental data files.
- Batch or titration data.
- Interactive fitting of experimental data.
- Stability constant refinement
- Factor analysis (principal component analysis)
- View molar absorbance spectra
- Tables of concentrations and observed and calculated data can be viewed
and copied to the clipboard
- Some plots can be copied to the clipboard in vector-graphic format
- Convert legacy (pHab) data
- Data file compatible with HySS
A project can be created using spectroscopic data in
- Individual (ASCII) files containing wavelength,.intensity data pairs.
- A Cary titration file
- An Ocean Optics titration file
- A composite data file. This is created in EXCEL by the user from spectra
in individual files.
- Interactive Help:70 pages, including context-sensitive help and keyword
Sample data sets
||Spectral data alone
||Spectral data with pH measurements
Determination of a protonation constant in strongly alkaline solution
Metal - ligand complexes
Metal - ligand complexes in non-aqueous solution
HypSpec designed to run on a PC under the Windows XP, Vista, 7 and 8 operating
systems. There are no specific system requirements,
What's new in HypSpec2014
- Refinement. This is the major change. Log
b is refined rather than the equilibrium constant
b. This has the effect that negative values
of the equilibrium constants are not possible. It makes the refinement more
stable and go somewhat faster. Protection against divergence is provided by
shift-cutting. Failure of shift-cutting is a common reason for premature termination
- Manual fitting. If there is more than one
titration curve each one is shown in a separate panel. This makes it possible
to annotate the x-axis of each curve with point number, titre, or pH (if applicable).
Molar ratio possible on the x-axis.
- Import routines. Import has been greatly simplified,
but many variables will have invalid default values. New routines have been
added for import of data from Cary and Ocean Optics spectrophotometers. .
- Conditions check. Before any calculation the
variables are checked for invalid values. The calculations can only proceed
when there are no invalid values.
- Model changes. It is now possible to alter
the order of the equilibrium constants and reagents.
- Initial values. Concentration is now the
default option. If a data file has initial values in mmoles, they will be
changed to concentration /moles dm-3.
- Electrode readings. Experimental electrode
readings may be in mV or pH units.
- Titration curves showing pH as a function
of titre can be viewed when the data allow.
- Wavelength unit may be specified - default
- Ionic charges of reagents and complexes may
- Sample data. Two new sets of sample data have
- Legacy data. pHab data may be imported. Hyperquad2006
combined data files are no longer supported.
Stability Constants home page