| abstract |
The present invention relates to physical chemistry and can be used for a quality test of liquids, in particular, multi-component liquid products, to ascertain the conformity of various process liquids, pharmaceutical preparations, foodstuffs, biological liquids to standard in pharmacology, food processing and chemical industries, and in medical diagnostics. The method of invention enables determining of the mechanical impedance within a drop ( 1 ) of test liquid having a specified volume, in the preferred embodiment, 5 mcl, placed on the surface of a piezoelectric resonator ( 3 ) of ultrasound frequencies, which provides for excitation of shear modes within drop ( 1 ) while it is drying up. The obtained time dependence of the mechanical impedance of drop ( 1 ) is used as the information parameter. This information parameter is rather sensitive to the state of the liquid-crystalline structure of multi-component liquids, therefore, comparing the obtained time dependence with the same data for the etalon specimen allows one to assess the composition of a multi-component liquid, test the quality of liquid products, for example, foodstuffs, assess the prospective effectiveness of medical treatment with various medical preparations through analysis of a biological liquid, etc. n In the apparatus of invention, the mechanical impedance of test liquid is determined from the disbalance voltage of a bridge circuit ( 9 ) comprising a piezoelectric resonator of ultrasound frequencies ( 3 ), in preferred embodiments, from the amplitude and/or phase of the disbalance voltage, which ensures high accuracy of measurements. |