MiPNet08.16 pH calibration

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Laboratory protocol: pH measurement and temperature dependence of pH.

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Oroboros (2014-03-06) Mitochondr Physiol Network

Abstract: Gnaiger E (2014) Laboratory protocol: pH measurement and temperature dependence of pH. Mitochondr Physiol Network 08.16(07):1-4.

pH of blood and intracellular compartments is tightly regulated. Blood pH at 37 °C is 7.4. However, when temperature is lowered, the pH of blood and of intracellular buffer systems increases, which has been reported as early as 1927 but was ignored for the following 30 years. The phenomenon of a change in blood pH with temperature of about -0.016 U/°C was rediscovered by comparative physiologists in studies of "cold blooded" vertebrates (turtles, fish), and is was recognized soon that the same pH/temperature relation applies to "warm blooded" mammals (rat, human). The physicochemical basis of pH/temperature relations and the consequences for acid-base balance and protein function were primarily analyzed by Rahn and Reeves (1979). Besides the importance for physiological and biochemical systems, the temperature dependence of pH of buffer systems has experimental significance for the measurement of pH at different temperatures, and for the choice of buffer systems when designing experiments at various temperatures.

» Product: Oroboros O2k, O2k-Catalogue

Keywords: HRR-MultiSensor

O2k-Network Lab: AT_Innsbruck_Oroboros


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Figure 1. Principle of a two-point calibration of a pH electrode system, at pH 6.00 and 8.00. (a) Signal before calibration (dotted line); (b) Calibration at pH 6 at electronic zero (0 mV), using the zero adjustment (+; additive as shown by the downwards arrows of equal length); (c) calibration of gain setting (slope) at pH 8, observing the pH of 2.0 units (x; multiplicative or proportional, as shown by the constant position of the 0 mV signal); (d) The full line of correspondence is obtained by shifting the entire curve to the correct absolute pH value (+, additive).

Further information

» O2k-pH ISE-Module
» In DatLab, the two-point calibration calculations are performed automatically (equations in DatLab 6: Calibration).
» Template: pH-Calibration-List.xls

Labels: MiParea: Instruments;methods 

Regulation: pH, Temperature 

HRR: pH, O2k-Manual