Microwave characterization of aqueous amino acid solutions using the multifrequency WGM resonator technique

Abstract Amino acids play essential role for humans. We studied the dielectric properties of the basic aliphatic amino acids and polar positive amino acids in solutions of different concentrations. The high-Q single microwave whispering gallery-mode (WGM) quartz dielectric resonator based technique, enhanced to a number of measurement frequencies, was applied. The technique allows liquid investigation of micro- to nano- liter volumes filled in microfluidic channel on six discrete frequencies in the 30–40 GHz range. The dependencies of the complex permittivity on the molar mass show almost linear behavior for aliphatic amino acids at different concentrations. The study results are in good agreement with the calculated data obtained by Cole-Cole equation.