Method and apparatus for measuring pH of low alkalinity solutions
First Claim
1. A method for measuring pH of a low alkalinity sample solution, comprising the steps of:
- providing a pH sensor array having a plurality of pH indicator films, each said pH indicator film having a different indicator concentration;
applying said sensor array to a series of pH standard solutions having fixed and known pH and alkalinity values;
simultaneously measuring a pH response for each pH indicator film of said sensor array;
generating a calibration equation for each pH indicator film that provides the apparent pH as a function of said measured pH response, said calibration equations are generated using said measured pH responses for each pH indicator film from said series of pH standard solutions;
applying said sensor array to a low alkalinity sample solution having an unknown pH and an alkalinity of less than 100 ppm;
calculating apparent pH values for each film from each corresponding calibration equation and said measured pH response; and
calculating the actual pH value for the low alkalinity sample solution using extrapolation.
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Abstract
Systems and methods are described for measuring pH of low alkalinity samples. The present invention provides a sensor array comprising a plurality of pH indicators, each indicator having a different indicator concentration. A calibration function is generated by applying the sensor array to a sample solution having a known pH such that pH responses from each indicator are simultaneously recorded versus indicator concentration for each indicator. Once calibrated, the sensor array is applied to low alkalinity samples having unknown pH. Results from each pH indicator are then compared to the calibration function, and fitting functions are extrapolated to obtain the actual pH of the low alkalinity sample.
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12 Claims
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1. A method for measuring pH of a low alkalinity sample solution, comprising the steps of:
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providing a pH sensor array having a plurality of pH indicator films, each said pH indicator film having a different indicator concentration; applying said sensor array to a series of pH standard solutions having fixed and known pH and alkalinity values; simultaneously measuring a pH response for each pH indicator film of said sensor array; generating a calibration equation for each pH indicator film that provides the apparent pH as a function of said measured pH response, said calibration equations are generated using said measured pH responses for each pH indicator film from said series of pH standard solutions; applying said sensor array to a low alkalinity sample solution having an unknown pH and an alkalinity of less than 100 ppm; calculating apparent pH values for each film from each corresponding calibration equation and said measured pH response; and calculating the actual pH value for the low alkalinity sample solution using extrapolation. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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Specification