METHOD AND DEVICE FOR DETERMINING CONCENTRATION OF HYDROGEN IONS Russian patent published in 2011 - IPC G01N27/416 

FIELD: chemistry.

SUBSTANCE: method of determining concentration of hydrogen ions by using electrodes with high internal resistance to measure electrical parameters of the analysed medium from the steady-state potential of the measured signal, which corresponds to the physical and chemical composition of the medium, which is formed from dynamic potential difference between the measuring and comparison electrodes of a measuring cell and recorded on the time interval between the beginning of measuring and achieving the upper threshold value in each measurement cycle. The beginning of the measurement cycle is marked by the amplitude of the measured signal reaching the level of the lower threshold value after forced discharge when the amplitude reaches the upper threshold value at the end of the previous measurement cycle. Reference medium with standardised electrical parameters which are also recorded on the test time interval from the beginning of measurement until achieving the upper threshold value in each test measurement cycle is introduced. The beginning of the test measurement cycle is marked by the amplitude of the measured signal reaching the level of the lower threshold value after forced discharge when the amplitude reaches the upper threshold value at the end of the previous test measurement cycle. The time constant of the analysed medium is determined from the ratio of time intervals of the analysed and reference media. The discrepancy is minimised through adaptation of the standardised time constant of the analysed medium through successive approximation, and the approximation result is identified as the real value of the steady-state potential of the analysed medium which is proportional to the unknown concentration.

EFFECT: high accuracy by reducing dynamic and systematic error.

2 cl, 5 dwg, 1 tbl