G. A. Mashevskiy

The monocrystalline LaF3- electrode is one of the most absolute and highly selective electrodes. It is recommended for fluoride excretion monitoring by the competient medical technologies list. (№ ФС-2006\0184 от 27.02.2006). At the same time the electrode is also selective to other complexes, located in human urine. In compliance with electrode calibration curve in healthy human urine detects F- = 2,5*10-5 М. Such diluted solutions are unstable and stay stable just few hours, then the fluoride concentration decreases. Still our research shows that LaF3 - electrode potential in human urine is very stable during 4-5 hours. Such stability can be only explained by phosphate ions presence in urine, and by buffer properties of H2PO4-/ HPO4-2. Such circumstance must be taken into account wile analyzing LaF3- electrode experimental data. During the research we analyzed urine probes measurements results, received from healthy persons and Saint-Petersburg hospital № 26 patients. Fluoride ion activity statistical estimations for different groups of patients were received. LaF3- electrode potential high stability in healthy men urine is marked. Physiological values of LaF3- electrode potentials in normal and pathological urines were accurate. The decreasing of LaF3- electrode potential marks phosphate and fluoride ions retention and is a poor prognostic factor. The LaF3- electrode application in multisensory system extends diagnostics capability during patients cure.