The pH-dependent distribution of the indicator dye tetrabromophenolphthalein ethyl ester (TBPE, chromoionophore VIII) between plasticized polymeric phase and aqueous solution is studied. The commonly utilized algorithms for partition properties calculation are evaluated experimentally in terms of their suitability for the ionized species. The physical-chemical characteristics of TBPE that determine its applicability for use in chemical sensors, namely, the lipophilicity and acidity constant are estimated in the hydrophobic polymeric phase for the first time. The distribution coefficients of the neutral (protonated) and ionized (deprotonated) forms of TBPE are determined in plasticized PVC/water biphase system as 7.2 and 3.8, respectively (logk, ionic strength 1 M, 25 °C). The acidity constant of TBPE in plasticized PVC membrane, pK_a^PVC−DOS, is estimated spectrophotometrically as 6.1 ± 0.2 log units. The results can be used for developing optical chemical sensors based on TBPE (chromoionophore VIII), in particular for predicting the sensor lifetime, optimization of the sensor operating range and measuring conditions.

研究了指示剂染料四溴酚酞乙酯（TBPE，生色团VIII）在增塑的聚合物相和水溶液之间的pH依赖性分布。根据其对电离物质的适用性，通过实验评估了用于分区特性计算的常用算法。TBPE的物理化学特性决定了其在化学传感器中的适用性，即亲油性和酸度常数是首次在疏水性聚合物相中进行估算。在增塑的PVC /水双相系统中，TBPE的中性（质子化）和离子化（去质子化）形式的分布系数分别确定为7.2和3.8（log k，离子强度1 M，25°C）。分光光度法估计增塑的PVC膜中TBPE的酸度常数p K _a ^{PVC - DOS}为6.1±0.2 log单位。该结果可用于开发基于TBPE（生色团VIII）的光学化学传感器，特别是用于预测传感器寿命，优化传感器工作范围和测量条件。