Automatic chemical analysis apparatus and electrical impedance spectrometry device

An automatic chemical analysis apparatus that dispenses a reagent and a sample to be analyzed into a reactor vessel and performs stirring by applying sonic waves to the reactor vessel, the apparatus comprising:

• a constant-temperature bath for keeping the reactor vessel in contact with constant-temperature water;
• a piezoelectric element mounted on the constant-temperature bath via a jig such as to contact the constant-temperature water on a constant-temperature water-side surface and generate the sonic waves;
• a plurality of constant-temperature water-side electrodes provided to the constant-temperature water-side surface of the piezoelectric element and a plurality of electrodes that are provided to another surface of the piezoelectric element;
• a driver that causes the piezoelectric element to generate the sonic waves by applying a voltage to each of the electrodes;
• an electronic circuit that measures the electrical impedance spectrum of each of the electrodes by applying a voltage to each of the electrodes;
• and
• a host computer configured to control the driver and the electronic circuit, wherein the host computer is configured to cause:
• the electronic circuit to detect a liquid surface position of a liquid to be stirred based on the absolute value of an electrical impedance at the time of resonance of each of the electrodes, and
• wherein the host computer is configured to:
• determine that the liquid surface position is a proper position when the absolute value of all the electrodes is within a predetermined normal range,
• estimate the liquid surface position according to the position of a specific electrode when the absolute value is within an intermediate range lower than the normal range in the electrodes above the specific electrode,
• determine that the liquid surface position is higher than the proper position when the absolute value exceeds the normal range in all the electrodes, and
• estimate the surface position of the constant-temperature water in the constant-temperature bath when the absolute value is within an air range lower than the intermediate range for any of the electrodes, and
• wherein the host computer is further configured to control the driver to cause the piezoelectric element to generate the sonic waves in different modes according to the electrical impedance spectrum of each of the electrodes by applying a voltage only to the electrodes at and below the liquid surface position and the surface position of the constant-temperature water in the constant-temperature bath.