New system based on RC circuit for determine the concentration of gold nanoparticles

I. URBINA MEDINA; E. GRUMEL; F. BREDICE; D. C. SCHINCA; L. B. SCAFFARDI

Optical Society of America

OSA

Lugar: Washington; Año: 2019

In this paper we present an alternative, low cost technique for real-time measurement of the concentration of a solute dissolved or suspended in a solvent. In particular this technique was used for the determination of standard gold nanoparticles (NPs) concentration in aqueous solution. The procedure is based on the measurement of the variation of the oscillation frequency (f) of a RC type sinusoidal wave generator circuit with respect to its base frequency. This change is produced when the capacitance of a parallel plane capacitor in the oscillator circuit is varied due a change in its dielectric permittivity. This change takes place when different dilutions or concentrations (C) of NPs are used as a dielectric. Two types of standard NPs manufactured by Sigma Aldrich were used: one of them was 10 nm in diameter (Gold Colloid code 741957, C0, 10nm ≈ 6 1012 Part./mL) and the other 5nm in diameter (code 741949, C0, 5nm ≈ 5.5 1013 Part./mL).The initial concentration (C0) provided by the manufacturer for each case was diluted in consecutive halves up to 1/32 of the initial concentration, for both sizes of NPs. In all cases, the volume of the standard solutions was 2 ml.The results allowed determining the concentration C of each dilution for both NPs sizes. The sensitivity of the method is demonstrated by the fact that it is possible to determine the concentration up to a lower limit of 3% C0, with high reproducibility.