Thank you for your reply.
Actually, i want low concentration. I need a reference to support the concentration of my solution that is because manual recommended me to select conc of electrolyte within 0.1-0.25 M and 'reference paper' of the manual ranged 0.01-0.25 M. I don't know why they have different range. Also, according to my runs, lower concentration had some error than higher conc. of electrolyte..
If you have any other reason or reference of it (0.1-0.25 or 0.01-0.25), please let me know. Thanks again!