Cook General BioTechnology (United States)

Electrical conductivity of a solution is a property that can be easily determined through the measurement of a conductivity probe. The present study demonstrates the measurements of electrical conductivity for two ternary solutions: glycerol/sodium chloride/water and ethylene glycol/sodium chloride/water. When the concentration of sodium chloride to water ratio (R) is fixed, the existence of either glycerol or ethylene glycol, both cryoprotective agents (CPAs), can be quantitatively determined by their depressive influence on electrical conductivity of the solution. The measurements were performed on solutions with a set of 10 different concentrations of CPAs, ranging from 3.2% to 50% (v/v), along with five ratios of NaCl/water solutions. Equations to fit the experimental measurements were devised to characterize the relations among electrical conductivity, CPAs concentration, and R. A conductivity meter used in this study required <5 s to read the solution's electrical conductivity, which is faster than the measurement using osmometry method. The charts of ternary solutions associated with their electrical conductivity and concentrations make it especially useful for monitoring the cryopreservation processes, including addition and removal of CPAs, to prevent osmotic damages to biological samples.