1982 Volume 31 Issue 9 Pages T65-T70
A spectrophotometric titration system was constructed with Oki IF-800 personal computer and Shimadzu UV-360 spectrophotometer. For the the titration system, series of spectra of equilibrium solution were automatically introduced to the personal computer by using linear amplifier and digital input interface, and these data were stored in floppy disk file. The file was used to calculate the number of absorbing species by matrix rank analysis and to determine their specta and underlying equilibrium constants. The system avoids the error-prone manual handling of a large amount of data, and also it saves time and can overcome some difficulties in spectrophotometry, such as overlapping of the spectra of similar species. As an example, the acid dissociation equilibria of the six thiazolyl-azo-benzoic acid derivatives were studied by this spectrophotometric titration system. The compounds have similar spectra at neutral and anionic form. Under the condition of addition of cationic one at pH range 18, three species were recognized by matrix rank analysis with this system. The equilibrium constants and each spectrum were obtained by the modification of the Newton-Gauss non-linear least squares method.
