AMPHOLYTIC DYES FOR SPECTROSCOPIC DETERMINATION OF PH IN ELECTROFOCUSING

Ampholytic dyes were studied for the purpose of spectroscopic monitori ng of the local pH of solutions within capillary systems used for the focusing and separation of ampholytes. The dyes are compounds selected from previously described aminomethylnitrophenols and also a group of compounds based on aminomethylated sulfonphthaleins. The suggested am pholytic dyes are good ampholytes and are also pH indicators with colo ur transition around the pH value. The possibility of the spectroscopi c monitoring of actual pH was verified in a system involving pH gradie nt ion chromatography with diode-array detection and on-line flow-thro ugh pH detection.