McGinness J E, Crippa P R, Kirkpatrick D S, Proctor P H
Physiol Chem Phys. 1979;11(3):217-23.
Hydrogen ion titration curves obtained on melanins prepared and modified differently show recognizable differences. Melanin prepared with NaOH exhibits irreversible loss of functional groups in the base range once titrated acidic. Melanin prepared with NH4OH shows two main branches selected by incubation at an extreme pH for 24 h. Longer exposure reveals other curves but they disappear once a 24-h schedule of titration is resumed. The existence of two major pH branches appears consistent with the oxidation-reduction properties of melanins. These results demonstrate the ability to obtain a reproducible feature in the hydrogen ion titration curves. Thus it is finally possible to quantitate CO2 adsorbed to melanin in solution at basic pH.
对不同制备和改性的黑色素进行氢离子滴定曲线测定，结果显示出可识别的差异。用氢氧化钠制备的黑色素在酸性滴定后，在碱性范围内官能团会发生不可逆损失。用氢氧化铵制备的黑色素在极端pH值下孵育24小时后显示出两个主要分支。更长时间的暴露会显示出其他曲线，但一旦恢复24小时的滴定程序，这些曲线就会消失。两个主要pH分支的存在似乎与黑色素的氧化还原特性一致。这些结果证明了在氢离子滴定曲线中获得可重复特征的能力。因此，最终有可能对碱性pH值下溶液中吸附在黑色素上的二氧化碳进行定量。
