3-(4-Tolylazo)phenylboronic acid as the active component of polyhydroxy compounds-selective electrodes

摘要

Ionophoric, extraction, acidic and hydrophobic properties of 3-(4-tolylazo)phenylboronic acid (TAPBA) were studied. Determined K_d value equals to 36 ± 2, pK_a equals to 8.6 ± 0.5. TAPBA extracts dobutamine from water into chloroform and transports it across a bulk chloroform membrane. The recovery is 835 (pH = 7.5), the transport rate -(6.5 ± 0.5) * 10~(-7) mol/h. ~1H and ~(13)C NMR data confirm the formation of an 1:1 complex between arylboronic acid and catecholamine. TAPBA was used as electrodeactive component of plasticized membrane electrodes with cationic and anionic responses to catecholamines and phenolic acids, respectively. For the diethyl sebacate-plasticized membrane, a slope of electrode function to dobutamine is 56 ± 2 mV/decade; the detection limit is 1.3 * 10~(-5) mol/l; the linear range -5 * 10~(-5)-1 * 10~(-2) mol/l; the working pH-range -4.8-7.6; the response time 5-10 s. ISE gives incomplete cationic function to less lipophilic catecholamines. The membrane with cationic additive shows an anionic response to caffeic acid in wide pH range.