Chemistry: analytical and immunological testing – Including titration or ph determination
Reexamination Certificate
2011-05-17
2011-05-17
Warden, Jill (Department: 1777)
Chemistry: analytical and immunological testing
Including titration or ph determination
C436S164000
Reexamination Certificate
active
07943391
ABSTRACT:
A device for the precise and accurate potentiometric pH measurements in situ. Embodiments of a potentiometric device according to the invention consist of one or more glass pH-sensitive electrodes connected to a potentiometer. A key feature of the device is that, rather than being calibrated conventionally with buffers, it can be calibrated with an in situ device that measures pH spectrophotometrically. Spectrophotometric pH measurements obtained via sulfonephthalein absorbance measurements are inherently calibrated (do not require buffers). Thus, devices according to the invention allow for continuous potentiometric pH measurements with occasional spectrophotometric calibrations. The spectrophotometric calibration device consists of a spectrophotometer with associated pumps for combining a sulfonephthalein pH indicator with the aqueous medium whose pH is to be measured. The device will record potentiometric pH measurements for an extended period of time until the spectrophotometric device is autonomously activated for another calibration. In this manner precise and accurate pH measurements can be obtained continuously in the environment, and the low energy expenditure of the potentiometric device provides excellent endurance. Also provided is a method and associated devices for spectrophotometrically determining the salinity of an aqueous medium.
REFERENCES:
Spectrophotometric Determination of Freshwater pH Using Bromocresol Purple and Phenol Red Wensheng Yao and Robert Byrne Environmental Science and Technology, 2001, 35, 1197-1201.
Redundant Chemical Sensors for Calibration-Impossible Applications J.C. Seiter and M.D. DeGrandpre Talanta 54 (2001) 99-106.
Gerido Dwan A
Lawson Michele L.
Smith & Hopen , P.A.
University of South Florida
Warden Jill
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