Leibniz Institute of Photonic Technology, Albert-Einstein-Str. 9, 07745 Jena, Germany.
Institute of Solid State Physics, Friedrich Schiller University Jena, Helmholtzweg 3, 07743 Jena, Germany.
Biosensors (Basel). 2023 Aug 24;13(9):841. doi: 10.3390/bios13090841.
We present a novel and easy approach using a silicon-based impedance chip to determine the concentration of the given aqueous buffer solution. An accurate determination of the post-dilution concentration of the buffers is necessary for ensuring optimal buffer capacity, pH stability, and to assess solution reproducibility. In this study, we focused on phosphate buffer as the test liquid to achieve precise post-dilution concentration determinations. The impedance chip consisting of a top gold ring electrode, where a test volume of 20 μL to 30 μL of phosphate buffer was introduced for impedance measurements within the frequency range of 40 Hz to 1 MHz. For impedance investigation, we used phosphate buffers with three different pH values, and the impedance was measured after diluting the phosphate buffers to a concentration of 1.00 M, 0.75 M, 0.50 M, 0.25 M, 0.10 M, 0.05 M, and 0.01 M. In order to analyze the distinctive changes in the measured impedance, an equivalent circuit was proposed and modeled. From the impedance modeling, we report that the circuit parameter R showed exponential dependence on the concentration of phosphate buffer and no dependence on the pH values of the phosphate buffer and on the added volume inside the ring electrode. The proposed silicon-based impedance chip is quick and uses reduced liquid volume for post-dilution concentration measurements of buffers and has perspective applications in the pharmaceutical and biological domains for regulating, monitoring, and quality control of the buffers.
我们提出了一种新颖且简便的方法，使用基于硅的阻抗芯片来确定给定的水溶液缓冲液的浓度。准确确定缓冲液的稀释后浓度对于确保最佳缓冲能力、pH 稳定性以及评估溶液重现性非常重要。在本研究中，我们专注于磷酸盐缓冲液作为测试液体，以实现精确的稀释后浓度测定。该阻抗芯片由一个顶部金环电极组成，在该电极中引入了 20μL 至 30μL 的测试体积的磷酸盐缓冲液，用于在 40Hz 至 1MHz 的频率范围内进行阻抗测量。为了进行阻抗研究，我们使用了三种不同 pH 值的磷酸盐缓冲液，并在将磷酸盐缓冲液稀释至 1.00M、0.75M、0.50M、0.25M、0.10M、0.05M 和 0.01M 的浓度后测量了阻抗。为了分析测量阻抗的显著变化，我们提出并建模了一个等效电路。从阻抗建模中，我们报告电路参数 R 呈指数依赖于磷酸盐缓冲液的浓度，而与磷酸盐缓冲液的 pH 值以及在环电极内添加的体积无关。所提出的基于硅的阻抗芯片快速且使用较少的液体体积进行缓冲液的稀释后浓度测量，在制药和生物领域具有监管、监测和缓冲液质量控制的应用前景。
