Analyzing the response of a contactless conductivity detector in capillary electrophoresis by a resonant method

作者：Kang, Qi; Zhang, Qing; Li, Yao Long; Li, Dong Dong; Shen, Da Zhong^*

来源：Chinese Chemical Letters, 2012, 23(7): 831-834.

DOI：10.1016/j.cclet.2012.05.011

• Contactless conductivity detector
• Equivalent circuit parameter
• Quartz crystal resonator
• Resonant method

We report a resonant method to measure the wall capacitance (C-w) and solution resistance (R-S) in a capacitively coupled contactless conductivity detector ((CD)-D-4). Under the typical operating conditions in capillary electrophoresis (I.D. 50 mu m, O.D. 360 mu m, electrode length of 4 mm, electrode gap of 1 mm, frequency of 200 kHz), the values of C-w measured in 1 and 20 mmol/L NaCl solutions are 2.8 and 32 fF, which are only 1.1% and 12% of prediction by the equation in references, respectively. The value of R-S is less than the prediction in solutions with kappa < 0.02 S/m. The response current of (CD)-D-4 is due to the change in C-w because the total impedance of a (CD)-D-4 is composed mainly by the impedance from C-w.

• 出版日期2012-7
• 单位山东师范大学