An impedance spectrometer for the metrology of electrolytic conductivity

Conductivity measurements of liquids ask for measurements of impedance spectra in a wide frequency range to identify stray parameters caused by electrode-surface effects. On low-conductivity liquids, like ultra-pure water, frequencies of interest range below those available on precision LCR meter. A new impedance spectrometer based on multifrequency excitation and discrete Fourier transform analysis is here presented. The spectrometer measures impedance spectra reaching frequencies in the mHz range. An example of measurement on a water sample and a comparison with a LCR meter are presented.