Colour specification of pyridine-2-aldehyde and 6-methylpyridine-2-aldehyde p-nitrophenylhydrazones as indicators for pH determination.
The physicochemical properties, chromaticity co-ordinates and chromatic parameters for pyridine-2-aldehyde p-nitrophenylhydrazone and 6-methylpyridine-2-aldehyde p-nitrophenylhydrazone (proposed as new indicators for calorimetric pH measurements) are reported. The sensitivity and rapidity of colour change have been evaluated in terms of specific colour discrimination (SCD), pH of maximum colour change and half band-width of change of SCD (in terms of pH). The chromatic separations calculated from the co-ordinates obtained by the CIE 1976 recommendations (CIELUV or CIELAB) and the LABHNU 1977 colour space are compared and correlated with the standard deviation of colour matching.
Fernandez
A M
AM
Department of Bromatology, Toxicology and Applied Chemical Analysis, Faculty of Pharmacy, University of Seville, 41012 Seville, Spain.
Chozas
M G
MG