O' Toole Martina, Lau King Tong, Diamond Dermot
Adaptive Information Clusters, National Centre for Sensor Research, School of Chemical Sciences, Dublin City University, Dublin 9, Ireland.
Talanta. 2005 Jun 15;66(5):1340-4. doi: 10.1016/j.talanta.2005.01.054. Epub 2005 Feb 26.
A novel inexpensive optical-sensing technique has been developed for colorimetric flow analysis. This sensing system employs two LEDs whereby one is used as the light source and the other as a light detector. The LED used as light detector is reverse biased with a 5-V supply so that the photocurrent generated by the incident light discharges the capacitance. Direct digital output is provided by a simple timer circuit that measures the time taken for this discharge process from 5V (logic 1) to 1.7V (logic 0). This sensing concept has been applied in flow analysis by constructing an optical flow cell with a pair of LEDs. Calibration of the integrated optical flow cell using a dye resulted in a linear response that obeys the Beer-Lambert law. The flow rate, dynamic range, sensitivity and limits of detection were investigated. The system was also used for pH determination in the range of pH 2.5-6.8 using bromocresol green (BCG). The pK(a) of BCG was successfully determined by this technique.
一种用于比色流动分析的新型廉价光学传感技术已经被开发出来。这个传感系统采用两个发光二极管，其中一个用作光源，另一个用作光探测器。用作光探测器的发光二极管由一个5伏电源反向偏置，使得入射光产生的光电流对电容放电。一个简单的定时器电路提供直接数字输出，该电路测量从5伏（逻辑1）到1.7伏（逻辑0）的放电过程所需的时间。通过构建一个带有一对发光二极管的光学流动池，这种传感概念已应用于流动分析中。使用一种染料对集成光学流动池进行校准，得到了符合比尔-朗伯定律的线性响应。研究了流速、动态范围、灵敏度和检测限。该系统还用于使用溴甲酚绿（BCG）在pH 2.5 - 6.8范围内测定pH值。通过该技术成功测定了BCG的pK(a)。
