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University of Montana

Michael D DeGrandpre

Andrew M Dickson

Todd Martz

A titration method uses a tracer in the titrant or titrand to quantify the amount of titrant added. The method does not require quantitative addition of titrant or sample. The tracer can be inert or can participate as an indicator of the titrant-analyte reaction. If the tracer is inert, an alternative method for monitoring the progress of the titration is required. The tracer concentration is quantified by an appropriate method depending upon the type of tracer and analytical performance desired (e.g. precision, accuracy). The method simplifies titrations because it eliminates the need for a precision dispensing device and analytical balance.

Titration method using a tracer to quantify the titrant

An apparatus and method for taking absorbance-based chemical measurements are described. In a specific embodiment, an indicator-based pCO(partial pressure of CO) sensor displays sensor-to-sensor reproducibility and measurement stability. These qualities are achieved by: 1) renewing the sensing solution, 2) allowing the sensing solution to reach equilibrium with the analyte, and 3) calculating the response from a ratio of the indicator solution absorbances which are determined relative to a blank solution. Careful solution preparation, wavelength calibration, and stray light rejection also contribute to this calibration-free system. Three pCOsensors were calibrated and each had response curves which were essentially identical within the uncertainty of the calibration. Long-term laboratory and field studies showed the response had no drift over extended periods (months). The theoretical response, determined from thermodynamic characterization of the indicator solution, also predicted the observed calibration-free performance.

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Missoula, MT, United States of America

Michael D DeGrandpre