disclosed is a tetra substituted cyclohexane having an ionophore in the one and two positions wherein the ionophore may be the same or different and is selected from the group consisting of a crown , a podand and a cryptand wherein the ionophore is capable of complexing with a metal or ammonium cation . positions four and five are substituted by an electron donor group and an electron acceptor group . also disclosed is a method for detecting the concentration of cations in a fluid by subjecting the fluid to the tetra substituted cyclohexane composition which will thereby complex the cation in the fluid . the cations are preferably alkali metal and alkaline earth metal cations . the fluid may be an aqueous or non - aqueous fluid or body fluids .