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31P Spectroscopy intracellular pH calculator

Application Tip
Thomas, Gregory Philips Healthcare • USA


In 31P Spectroscopy the relation between pH and the chemical shift of Pi (Inorganic Phosphate) is well documented and can be calibrated for very accurate non-invasive intracellular pH measurements.

The downloadable spreadsheet calculator provides a convenient method to calculate the intracellular pH using the chemical shift difference between Pi (Inorganic Phosphate) and PCr (Phospho-creatine).

Using the 31P spectroscopy intracellular pH calculator

1. Download the 31P Spectroscopy intracellular pH calculator below to calculate pH utilizing the formula:

2. First, the chemical shift difference information can be found by clicking right mouse on a 31P spectrum in
Spectroview (ppm scale), and selecting Difference Mode from the drop down.

Next, green dotted vertical lines will appear; place one line on the Pi peak and the other on the PCr peak (Fig. 2). Record the Dx= measurement value (red box in Fig 2).

3. Enter the Dx= value from step 2, into the pH Calculator (in the blue box labeled
Chem Shift Diff Pi & PCr);

Then press the  = button on the calculator (Fig. 3).

4. The resultant intracellular pH value will be displayed.


pH = pKa + log[chem shift (Pi-PCr) - chem shift acid/chem shift base - chem shift (Pi-PCr)]

Example: Dx=4.840

pH = 6.73 + log[4.840 - 3.275/5.685 – 4.840]

pH = 6.73 + log[1.565/0.845]

pH = 6.73 + log[1.852071]

pH = 6.73 + 0.267658

pH= 6.998

Fig. 2 Fig. 3
Fig. 2
Fig. 3

Click below to download the 31P Spectroscopy intracellular pH calculator:

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Nov 19, 2013

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Application Tip
31P, Multi Nuclei, pH, Phosphorus, Spectroscopy

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