ph_temperature_compensation.h File Reference

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Functions
double	temperature_compensated_ph (double measured_ph, double temperature_celsius)
	This function applies Nernst-based automatic temperature compensation to adjust a pH reading measured at temperature T, translating it to the equivalent value at 25 °C. More...

Function Documentation

temperature_compensated_ph()

double temperature_compensated_ph	(	double	measured_ph,
		double	temperature_celsius
	)

This function applies Nernst-based automatic temperature compensation to adjust a pH reading measured at temperature T, translating it to the equivalent value at 25 °C.

pH electrodes become more sensitive as temperature increases due to the Nernst equation: slope = (2.303 * R * T) / (n * F) ≈ 0.1984 × T (in Kelvin)

This slope determines how much the electrode voltage changes per pH unit. At 25°C (298.15 K), the slope is ~59.16 mV/pH — the standard used during calibration.

If a pH value is measured at a different temperature, its deviation from pH 7.0 must be scaled back to match what the reading would have been at 25°C.

This function assumes the input pH was measured using the slope corresponding to the actual in-situ temperature, and adjusts it to match the reference slope at 25°C.

Parameters

measured_ph	pH value measured at in-situ temperature (not yet compensated)
temperature_celsius	in-situ temperature at time of measurement

Returns

double pH value compensated to 25°C conditions

Note

This does not convert voltage to pH, but adjusts an already computed pH value.

References:

• https://mantech-inc.com/faq/how-does-mantech-account-for-temperature-compensation-and-correction-in-ph-measurements/
• https://atlas-scientific.com/ph-temperature-calculator/
• https://www.horiba.com/usa/water-quality/support/technical-tips/bench-meters/automatic-temperature-compensation-in-ph-measurement/

Definition at line 28 of file ph_temperature_compensation.h.