方波激发非接触式电导检测器信噪比的影响因素研究

Factors effecting on signal-to-noise ratio of square wave excitation contactless conductivity detection

研制了用于毛细管电泳的方波激发非接触式电导检测器(CCD)并详细考查了对检测器信噪比影响较大的几个重要因素,包括激发频率和运算放大器、基线分压电路和A/D转换器、数字低通滤波;以及常见缓冲体系2-(N-吗啡啉)-乙磺酸/组氨酸(MES/His)体系中电解质浓度,添加剂十六烷基三甲基溴化铵(CTAB)对金属离子的检出信号的影响。所得的结果对于该类检测器的设计和优化具有参考价值。

A novel square wave excitation contactless conductivity detection was presented, and some significant factors effecting on the signal-to-noise （S/N） ratio of the detector were examined in detail. The assessments of S/N ratios were carried out, including the optimization of the excitation frequency of the square wave and the performance of the operational amplifier, both the parameters of the background baseline voltage-limited resistance and the A/D converter, the digital low-pass filtering parameters, as well as the concentration of the common running buffer, 2-（N-morpholino） ethanesulfonic acid/L-Hisdine （MES/His） and the electroosmosis flow modified reagent, e. g. cetyhrimethylammonium bromide （CTMAB）. The obtained results are significant references for optimization of the contactless conductivity detector.