STRATEGIES FOR LOW DETECTION LIMIT MEASUREMENTS WITH CYCLIC VOLTAMMETRY
STRATEGIES FOR LOW DETECTION LIMIT MEASUREMENTS WITH CYCLIC VOLTAMMETRY
复制标题
DOI：
10.1021/ac00024a030
复制
发表时间：
1991-12-15
影响因子：
7.4
通讯作者：
WIGHTMAN, RM
中科院分区：
文献类型：
--
作者：
WIEDEMANN, DJ;KAWAGOE, KT;WIGHTMAN, RM
循环伏安法是一种涂有nafion的碳纤维电极，用于检测流动注射装置和麻醉大鼠大脑中的微量多巴胺浓度。为了提高信噪比，确定了循环伏安法中的噪声源，并制定了降低噪声的策略。使用恒电位器后，测量到的噪声可与电流传感器反馈电阻的约翰逊噪声相媲美。额外的噪声来自所使用的波形发生器，在某些情况下是线路噪声。通过启动与线路频率同相或180度异相的每个循环伏安图来鉴别线路噪声。在体内使用时，动物的生理活动也会产生额外的噪声。发现检测限与基于伏安形状和实测噪声的模拟所预测的限非常接近。通过使用适当的模拟和数字滤波、集合平均和重复循环伏安图的适当定时，提高了检测限。这些技术的结合使用可以在体内检测大约100 nM的多巴胺，信噪比为25。
Cyclic voltammetry of Nafion-coated, carbon-fiber electrodes is used to detect trace concentrations of dopamine, both in a flow injection apparatus and in the brain of an anaesthetized rat. To improve signal-to-noise ratios, the sources of noise during cyclic voltammetry have been determined and strategies have been developed to decrease the noise. With the potentiostat employed, the measured noise is comparable to that expected for Johnson noise from the feedback resistor of the current transducer. Additional noise arises from the waveform generator employed and, in some cases, line noise. Line noise is discriminated against by starting each cyclic voltammogram either in phase or 180-degrees out of phase with the line frequency. When used in vivo, additional noise also arises from the physiological activity of the animal. Detection limits are found to closely correspond to those predicted on the basis of simulation of the voltammetric shape and the measured noise. Detection limits are improved by the use of appropriate analog and digital filtering, ensemble averaging, and appropriate timing of repetitive cyclic voltammograms. The combined use of these techniques enables the in vivo detection of approximately 100 nM of dopamine with a signal-to-noise ratio of 25.