conductivity solution recipe
It can be, because of the complex relations when discussing frequency dependance. If you are looking for something simple, than you should choose chemically pure compounds or simple mixtures with well defined dielectric properties and low frequency dependance.
Most literature is about describing the properties of an empirical existing liquid, e.g. sea-water at a known salinity and temperature. Making a standard or reference liquid is something different. As far as I remember, standard solutions exist for technical conductivity measurements.