Polymeric liquid membrane electrodes incorporated with macrocyclic hexaamines for screening adenine nucleotides

Lipophilic macrocyclic hexaamines supported by a poly(vinyl chloride) PVC matrix were used for the construction of liquid membrane electrodes sensitive toward adenine nucleotide polyanions. The membrane potential strongly depended on the pH of the sample solution. This phenomenon occurs due to the ability of the ionophore to accept protons. Therefore, the optimum pH was determined based on potential pH profile. The potential measurements were carried out at pH 6.0 in the presence of 10(-2) M 2-[N-morpholino] ethanesulfonic acid (MES) buffer. The potential response of these electrodes toward ATP(-4) and/or HATP(-3) was close to the Nernstian slope. The selectivities against ADP(-3), AMP(-2), HPO(4)(-2), and monovalent inorganic anions were estimated using the matched potential method. Chloride ions slightly affected potential response of the electrodes toward ATP(-4)/HATP(-3). The influence of ionophore chemical structure on the selectivity and the sensitivity of these electrodes is briefly discussed.