Spectrophotometric and potentiometric pH-titrations of the Neurotransmitter Intepirdine hydrochloride INN·HCl for three dissociation constants determination were compared. A nonlinear regression of the pH-spectra (REACTLAB, SQUAD84) and of the pH-titration curve (ESAB) determined three multiple dissociation constants. A sparingly soluble neutral molecule LH of INN·HCl was capable of protonation to form the still soluble three cations LH₂⁺, LH₃²⁺ and LH₄³⁺ in pure water. Although the change of pH somewhat less affected changes in the chromophore, three consecutive thermodynamic dissociation constants were estimated pK^T_a1 = 5.64, pK^T_a2 = 7.31, pK^T_a3 = 8.85 at 25 °C and pK^T_a1 = 5.51, pK^T_a2 = 7.15, pK^T_a3 = 8.77 at 37 °C. The graph of molar absorption coefficients of variously protonated species according to wavelength shows that the spectrum of species LH₂⁺ and LH vary in colour, while protonation of chromophore LH₂⁺ to LH₃²⁺ and LH₄³⁺ has less influence on chromophores in Intepirdine hydrochloride molecule. As the spectral response on the chromophore in the INN·HCl molecule is not large, it was necessary to test a reliability whether it is possible to estimate the dissociation constants even from such small spectrum changes. Three multiple thermodynamic dissociation constants of 3 × 10⁻⁴ M INN·HCl were determined by the regression analysis of potentiometric titration curves pK^T_a1 = 5.14, pK^T_a2 = 8.38, pK^T_a3 = 9.33 at 25 °C and pK^T_a1 = 5.17, pK^T_a2 = 8.31, pK^T_a3 = 9.07 at 37 °C. The macro-dissociation constants of INN·HCl were estimated according to the chemical structure analyzed by two pK_a predictors, the MARVIN and ACD/Percepta programs. The resulting protonation scheme of INN·HCl was suggested.

比较了神经递质Intepirdine盐酸盐INN·HCl的分光光度法和电位pH滴定法测定了三个解离常数。pH光谱（REACTLAB，SQUAD84）和pH滴定曲线（ESAB）的非线性回归确定了三个多重解离常数。少量溶解的INN·HCl中性分子LH能够质子化，从而在纯水中形成仍可溶的三个阳离子LH ₂ ⁺，LH ₃ ²⁺和LH ₄ ³⁺。尽管pH的变化对发色团的变化影响较小，但估计三个连续的热力学解离常数p K ^T _a1  = 5.64，p K ^T_a2  = 7.31， 在25°C时p K ^T _a3 = 8.85， 在37°C时p K ^T _a1  = 5.51，p K ^T _a2  = 7.15，p K ^T _a3 = 8.77。各种质子化物质的摩尔吸收系数随波长变化的曲线图表明，LH ₂ ⁺和LH物质的光谱颜色不同，而生色团LH ₂ ⁺到LH ₃ ²⁺和LH ₄ ^3+的质子化对盐酸恩替比丁分子中的生色团影响较小。由于INN·HCl分子中发色团的光谱响应不大，因此有必要测试可靠性，即使从如此小的光谱变化中也可以估计解离常数。 通过电位滴定曲线的回归分析确定三个多重热力学解离常数3×10 ^-4 M INN·HCl p K ^T _a1  = 5.14，p K ^T _a2  = 8.38，p K ^T _a3  = 9.33在25°C和p K ^T _a1  = 5.17，p K ^T _a2  = 8.31，p K ^T 在37°C下_a3 = 9.07。根据由两个p K _a预测因子MARVIN和ACD / Percepta程序分析的化学结构，估算INN·HCl的宏观解离常数。提出了INN·HCl的质子化方案。