I suspect this is very likely a sentence adapted from of one of the methods from the Russian State Pharmacopoeia (RSP), which has numerous entries for the adverb «потенциометрически» (Eng. “potentiometrically”).
For instance, there is a nearly identical match in the normative section for the preparation of acetate buffer solution, ОФС.1.3.0003.15-1.27 Ацетатный буферный раствор рН 5,0:
К 120,0 мл 6,0 г/л раствора уксусной кислоты ледяной прибавляют 100,0 мл 0,1 М раствора калия гидроксида и 250,0 мл воды, перемешивают. Доводят рН до 5,0 потенциометрически с помощью 6 г/л раствора уксусной кислоты ледяной или 0,1 М раствора калия гидроксида и доводят объём раствора водой до 1000,0 мл.
RSP underwent a vigorous clean-up since the Soviet era when it was primarily original, and currently it is mostly translated from the European Pharmacopoeia (EP), so I decided to take a look at the corresponding entry in EP 8.0 (currently invalidated, but one can at least find bits of it in the internet), Section 4.1.3. Buffer solutions:
Acetate buffer solution pH 5.0. 4009100.
To 120 mL of a 6 g/L solution of glacial acetic acid R add 100 mL of 0.1 M potassium hydroxide and about 250 mL of water R. Mix. Adjust the pH to 5.0 with a 6 g/L solution of acetic acid R or with 0.1 M potassium hydroxide and dilute to 1000.0 mL with water R.
EP omits the details as to how the pH is controlled, but there are several phrases in the prior text
Adjust to pH … with …, monitoring the pH potentiometrically
referring to the section 2.2.3. Potentiometric Determination of pH, so I think the phrase that you have proposed
Adjust pH of the solution potentiometrically to 5.0±0.1 with acetic acid.
is perfectly fine and will be correctly understood as a more literate alternative to something like "the pH was determined with a pH meter."
A couple of similar textbook-usecases:
Concise Encyclopedia Chemistry [2, p. 803]:
The pH of a solution is determined experimentally with a suitable pH color indicator (see Indicators) or potentiometrically, with a pH meter (see Glass electrode).
Fundamentals of Electrochemistry [3, p. 590]:
The concentrations of hydrogen ions (solution pH) and of a number of other inorganic ions … are determined potentiometrically.
- Council of Europe; European Directorate for the Quality of Medicines & Healthcare. European Pharmacopoeia 8.0; European Directorate for the Quality of Medicines & Healthcare, Council of Europe: Strasbourg, 2013.
- Concise Encyclopedia Chemistry, English language ed., 2nd ed.; Scott, T., Eagleson, M., Eds.; de Gruyter: Berlin; New York, 1994.
- Bagot︠s︡kiĭ, V. S. Fundamentals of Electrochemistry, 2nd ed.; The Electrochemical Society series; Wiley-Interscience: Hoboken, N.J, 2006.