Buffers for the physiological pH range: acidic dissociation constants of zwitterionic compounds in various...

The measurement of pH of a physiological buffer is an integral part of clinical diagnosis. For the standardization of pH and control of acidity in the physiological region of pH 7 to 9, as found in blood and plasma. Good et al., Ferguson et al., and Bellini et al. have listed hydrogen buffers which are N-substituted amino acids compatible with common biological media. Recently, the acid base behavior of BICINE, in aqueous solution and in different solvent mixtures has been studied by us. Other investigators reported similar results for (CAPS and CAPSO), (BES), (ACES and CHES), TRICINE, TES, ADA, (HEPPS and MOPSO), (MOPS), and (MOBS and HEPBS). These studies have provided precise knowledge about the suitability of a biological buffer. No work seems to have been done on the determination of second stage dissociation constants of 2-(4-Morphlinomethyl)propenoic acid, 2-[bis(2-hydroxyethyl)amino methyl]propenoic acid, 2-[bis(2-hydroxypropyl)aminomethyl]propenoic acid, and 2-[N-ethyl-N-(2-hydroxyethyl)aminomethyl]propenoic acid in aquo-organic solvent mixtures.