改进调制脉冲式电子捕获检测器电路的设计及其应用  

Design and Application of Improved Pulse-modulated Electron Capture Detector Circuit

作　　者：邢小兵 强伟锋 赵天悦 Xing Xiaobing;Qiang Weifeng;Zhao Tianyue(Beijng Purkinje General Instrument Co.,Ltd,Beijing 101200,China)

机构地区：[1]北京普析通用仪器有限公司,北京101200

出　　处：《现代科学仪器》2023年第6期5-10,共6页Modern Scientific Instruments

基　　金：中关村国家自主创新示范区高精尖产业协同创新平台项目:现代农业检测技术与装备协同平台支持。

摘　　要：电子捕获检测器是气相色谱分析中常用的检测器之一,检测器电路主要有单电极恒定脉冲型和单电极调制频率型。本文设计一种改进的调制脉冲型电路,包括浮地电压和可调参比电流单元、信号采集放大单元、FPGA控制单元、信号收集驱动单元、电荷守恒脉宽调制单元和信号输出单元等,对调制频率后的信号根据电荷守恒进行脉宽调制,降低输出噪声,提升信噪比,可以有效降低检测器的检出限。经测试,仪器检出限为2.3×10^(-14)g/mL,与典型电路的检测器相比,检出限降低了近1个数量级。Electron capture detector is one of the commonly used detectors in gas chromatography analysis.The detector circuits mainly include single-electrode constant pulse type and single-electrode modulation frequency type.In this paper,an improved modulated pulse type circuit is designed,including floating ground voltage and adjustable reference current unit,signal acquisition and amplification unit,FPGA control unit,signal acquisition and driving unit,charge conservation pulse width modulation unit and signal output unit,etc.The detection limit of the detector can be effectively reduced by pulse width modulation of the modulated frequency signal according to the charge conservation,which can reduce the noise of output signaland improve the signal-to-noise ratio.After testing,the instrument detection limit is 2.3×10^(-14)g/mL,which is nearly 1 order of magnitude lower than the detector of a typical circuit.

关 键 词：电子捕获检测器 气相色谱 调制脉冲 电荷守恒 脉宽调制 

分 类 号：TH832[机械工程—仪器科学与技术]