| Popis: |
The mixed dissociation constants of four drugs – haemanthamine, lisuride, metergoline and nicergoline – at various ionic strengths I of range 0.01 and 0.6 and at temperatures of 25 °C and 37 °C were determined using SPECFIT32 and SQUAD(84) regression analyses of the pH-spectrophotometric titration data. A proposed strategy for efficient experimentation in a dissociation constants determination, followed by a computational strategy for the chemical model with a dissociation constants determination, is presented on the protonation equilibria of haemanthamine. Indices of precise methods predict the correct number of components, and even the presence of minor ones when the data quality is high and the instrumental error is known. The thermodynamic dissociation constant p K a T was estimated by non-linear regression of {pKa, I} data at 25 °C and 37 °C: for haemanthamine p K a T = 7.22 ( 1 ) and 7.05 (2), for lisuride p K a T = 7.87 ( 1 ) and 7.59 (1), for metergoline p K a T = 7.62 ( 1 ) and 7.38 (1), for nicergoline p K a , 1 T = 7.94 ( 1 ) and 7.69 (1). Goodness-of-fit tests for various regression diagnostics enabled the reliability of the parameter estimates to be found. |
Full Text from ScienceDirect