Toshiaki Nomura

Frequency shifts of piezoelectric quartz crystals immersed in organic liquids

A piezoelectric quartz crystal oscillates in organic liquids. The frequency change (ΔF) depends on the density (d) and viscosity (η) according to ΔF = ad1/2 + bη1/2 — c, where a, b and c, are constants depending on the crystal.

Electrolytic determination of nanomolar concentrations of silver in solution with a piezoelectric quartz crystal

Abstract Silver in solution is determined in situ by the frequency change of a piezoelectric quartz crystal on electrodeposition on the electrode of the crystal. The electrolyte solution flows through a cell containing the platinum-plated electrode (cathode) of the quartz crystal, a coiled platinum-wire anode and a silver—silver(I) chloride reference electrode, and is electrolyzed at —0.2 V vs. Ag AgCl . The frequency change is proportional to the silver concentration in the range 10 -5 –5 × 10 -7 M after electrodeposition for 5 min, and in the range 10 -8 –10 -9 M by recycling 20 ml of the solution over the electrodes for 3 h.

Behaviour of piezoelectric quartz crystals in solutions with application to the determination of iodide

Abstract The frequency of oscillation of a piezoelectric quartz crystal immersed in solution changes with the temperature of the solution and with the ambient temperature of the oscillator, especially where the latter is transistorized. The frequency is also affected by the specific gravity, viscosity and specific conductivity of the solution. When all the properties are maintained constant, iodide present in the solution electrodeposits on the silver electrodes of a crystal to produce a reproducible change in frequency which allows iodide to be determined in the range 0.5–7 μM. Thiosulphate, cyanide, sulphide, Fe(III), Hg(II) and Ag interfere, but procedures for preventing their interference are given.

Electrode-separated piezoelectric quartz crystal and its application as a detector for liquid chromatography

Abstract The electrodes were removed from both surfaces of a piezoelectric quartz crystal and platinum electrodes were set on both sides of the crystal plate a few tenths of a millimetre apart. The spaces were filled with liquids. This system, called an electrode-separated piezoelectric quartz crystal (PQC), oscillation when the electrodes were connected to an oscillator, and the frequency varied with the density, viscosity and specific conductivity of the liquid like a normal piezoelectric quartz crystal having vacuum-evaporated metal electrodes, and the permittivity of the liquid also varied with mass change on the surface of the crystal plate in the liquid. The electrode-separated PQC was used as a detector for liquid chromatography.

Internal electrolytic determination of silver in solution with a piezoelectric quartz crystal

Abstract The piezoelectric quartz crystal is connected to an oscillator constructed with an integrated circuit, which has insufficient potential between the electrodes to electro-deposit metal ions spontaneously from the solution. Silver (10 −5 –10 −6 M) in solution is determined by internal electrodeposition on the platinum electrodes of the crystal connected to a zinc rod immersed in the same solution.

Effect of metal ions on a piezoelectric quartz crystal in aqueous solution and the adsorptive determination of iron(III) as phosphate

At 1.5 V applied between the electrodes on the piezoelectric crystal, many metals electrodeposit on an electrode so that the frequency changes. Iron(III) (1 × 10−5-1 × 10−4 M) can be determined by adsorption of iron(III) phosphate which also causes a frequency change. Electrodeposition can be prevented by covering one electrode with a thin glass plate.

Determination of micromolar concentrations of cyanide in solution with a piezoelectric detector

Abstract The silver plated electrodes of a piezoelectric quartz crystal are partly dissolved by cyanide in pH 9.6 solution during a 15-min immersion. The resulting frequency change of the crystal, measured in air, is proportional to cyanide concentration over the range 10-7–10-5 M.

Determination of silver in solution with a piezoelectric detector after electrodeposition

Silver in solution is determined in situ by frequency change of a piezoelectric quartz crystal due to electrodeposition on the electrode of the crystal immersed in the solution. A test solution containing EDTA for masking other metal ions flows through a thermostated cell which contains the crystal with platinum-plated electrodes. The frequency change is proportional to the silver concentration in the range 10−6−3 × 10−5 M after electrodeposition for 10 min, and 2 × 10−7−1 × 10−6 M for 1 h.

Electrodeless piezoelectric quartz crystal and its behaviour in solutions

Abstract An electrodeless piezoelectric quartz crystal system was constructed with a quartz crystal plate, electrolyte solutions and platinum plates or rods immersed in the solutions for connecting to an oscillator, instead of the electrodes. The crystal without electrodes oscillates in the solutions. The frequency varies with temperature, specific conductance of the solutions and the mass change of the plate caused by the adsorption of material from the solution in, the same way as a normal piezoelectric quartz crystal with electrodes.

Single-drop method for determination of cyanide in solution with a piezoelectric quartz crystal

Abstract The change in frequency of a horizontal quartz crystal in contact with a single drop of solution is measured. When the gold electrode of the crystal is dissolved by reaction with cyanide in alkaline solution, the further change of frequency is linearly related to cyanide concentration in the range 10 -3 –10 -4 M at pH 10.4. Only silver(I) and mercury(II) interfere if EDTA is added.