Try to fit your impedance profile with equivalent circuit, so that you can get the values of all resistance. Or else in X axis, from zero to your first impedance point known as the solution resistance.
Thank you for your answer Andreas Heyn. But what I want is a method to get it from my data since that I don't have the value when Zim=0 (as you can see in the attached image).
Use a soft ware by Gamry or elsewhere to best fit your Nyquist data to Randle's equivalent semi-circle. Then,the lower intersection point of Randle's equivalent semi-circle with the abscissa ordinate(X-axis or horizontal axis) wii be the solution (Ohmic)resistance;Rs.
Try to fit your impedance profile with equivalent circuit, so that you can get the values of all resistance. Or else in X axis, from zero to your first impedance point known as the solution resistance.
your EIS locus is, mainly, on a WE-"context", all about a WE focus, ... not about your solution properties.
However, a part, only, of your solution resistance (as a "byproduct"-hint) might be estimated as a small percentage, contained in the composite resistance value, proposed by the "Gamry[1] method"; then, proceed with a helpful fitting[2].
Also, if the electrolytes' resistance is critical for your project then, apart from a specific (descent) measurement, you can have a realistic (approximative resistance) value. Remake similar EIS, but, use, now, three different electrolyte's concentrations; the above fitting-method[2] will result in a useful (practical) resistance value, e.g. get the (initial) electrolyte(s) resistance, from these (three) Nyquist Plot(s), by excluding the other[3] values, excluded, virtually, from the common EIS[4] (WE-locus).
Also, we could try to adjust the position of the RE (referencer electrode), in respect to the direction of the cell's current (iWE,CE). The most interesting locations are, at least, three :
Try to fit your Nyquist plot on CHI or autolab analyser by simulating it or fit into the software. It is much better than guessing on manual method and off course it is not possible in your system at all. Similar nyquist plot appears in conducting polymeric study.