Department of Inorganic and Analytical Chemistry, University of Geneva, Quai Ernest-Ansermet 30, CH-1211 Geneva, Switzerland.
ACS Sens. 2020 Mar 27;5(3):650-654. doi: 10.1021/acssensors.0c00031. Epub 2020 Mar 5.
Potentiometric pH probes remain the gold standard for the detection of pH but are not sufficiently sensitive to reliably detect ocean acidification at adequate frequency. Here, potentiometric probes are made dramatically more sensitive by placing a capacitive electronic component in series to the pH probe while imposing a constant potential over the measurement circuit. Each sample change now triggers a capacitive current transient that is easily identified between the two equilibrium states, and is integrated to reveal the accumulated charge. This affords dramatically higher precision than with traditional potentiometric probes. pH changes down to 0.001 pH units are easily distinguished in buffer and seawater samples, at a precision (standard deviation) of 28 μpH and 67 μpH, respectively, orders of magnitude better than what is possible with potentiometric pH probes.
电位 pH 探头仍然是检测 pH 的金标准，但它们的灵敏度不够高，无法以足够的频率可靠地检测海洋酸化。在这里，通过在 pH 探头串联一个电容电子元件，同时在测量电路上施加一个恒定电势，使电位探头的灵敏度大大提高。每次样品变化都会引发一个电容电流瞬变，很容易在两个平衡状态之间识别出来，并进行积分以显示累积电荷。与传统的电位 pH 探头相比，这提供了更高的精度。在缓冲液和海水中，很容易区分低至 0.001 pH 单位的 pH 变化，其精度（标准偏差）分别为 28 μpH 和 67 μpH，比使用电位 pH 探头要好几个数量级。
