HypSpec2014

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.

References

These references to precursor programs give the basic principles, but they are somewhat out of date as the algorithms have been changed extensively.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.

Functions

• 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

Experimental Data

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.

Help file

• Interactive Help:70 pages, including context-sensitive help and keyword search.

Sample data sets

	Spectral data alone	Spectral data with pH measurements
Titration	Determination of a protonation constant in strongly alkaline solution Metal-ligand complexes(3)	Metal - ligand complexes
Batch	Metal - ligand complexes in non-aqueous solution Luminescence data	Polybasic acid

System requirements

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 of refinements.
• 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 unit nm.
• Ionic charges of reagents and complexes may be displayed.
• Sample data. Two new sets of sample data have been added.
• Legacy data. pHab data may be imported. Hyperquad2006 combined data files are no longer supported.

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