Department of Inorganic and Analytical Chemistry, University of Geneva, Quai Ernest-Ansermet 30, CH-1211, Geneva, Switzerland.
Anal Chim Acta. 2021 Apr 15;1154:338225. doi: 10.1016/j.aca.2021.338225. Epub 2021 Feb 5.
The deprotonation degree of the lipophilic pH indicator dye (chromoionophore) in ionophore-based ion optodes (so-called bulk optodes) has traditionally been measured spectrophotometrically. This makes it difficult to obtain spatially resolved concentration information, for example in the study of heterogenous systems. This article reports on a new colorimetric method that relies on a ratiometric image analysis. The acquision of image data allows one to map the deprotonation degree in two dimensions, which in turn is used to obtain the spatially-resolved ion concentration of the image. Using the detection of potassium as an example, the deprotonation degree data calculated on the basis of image analysis correlate quantitatively with those from spectrophotometry. They showed no dependence on the type of camera used in spite of their different gamma correction values and spectral sensitivities, as expected from theory. As an example, the method is successfully applied to the pixel level analysis of an ensemble of pictures acquired at different times to spatially and temporally observe potassium ion diffusion into an agarose gel containing a potassium-selective optical sensor microemulsion.
亲脂性 pH 指示剂染料（显色团）在基于离子载体的离子光导纤维（所谓的体相光导纤维）中的去质子化程度传统上是通过分光光度法来测量的。这使得很难获得空间分辨的浓度信息，例如在研究多相体系时。本文报道了一种新的比色法，它依赖于比率图像分析。图像数据的获取可以在二维空间上绘制去质子化程度，进而用于获得图像的空间分辨离子浓度。以钾的检测为例，基于图像分析计算出的去质子化程度数据与分光光度法的定量相关。与预期的理论一致，它们不依赖于所使用的相机类型，尽管它们的伽马校正值和光谱灵敏度不同。例如，该方法成功地应用于在不同时间获取的一组图像的像素级分析，以空间和时间方式观察钾离子扩散到含有钾选择性光学传感器微乳液的琼脂糖凝胶中。
