Comparison and characteristics of pH meters

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Photo (left) and schematic (right) of a glass pH electrode for measuring acidity. For translation of the German labels see LEO.
Photo (left) and schematic (right) of a glass pH electrode for measuring acidity. For translation of the German labels see LEO.

Measuring the acidity of a typically aqueous solution is a frequent task in a life science lab. A larger variety of pH meters are available to make these measurements. Their characteristics are compared below. Please add a description of your own machines including their pros and cons below.

Price vs. precision

product price precision comment
pH paper €5 ±1 most have a scale of 1 pH unit & a similar error
handheld Hanna X208.1 €50 [1] ±0.1 Hanna pHep, electrodes cannot be exchanged
handheld Hanna HA66.1 €100[2] ±0.05 Hanna pHep 5, waterproof, spare electrodes
unit w sep. electrode Hanna N541.1 €250 [3] ±0.01 Hanna HI 83141, separate temp. sensor (less wear)
tabletop Hanna PE50.1 €580 [4] ±0.001 Hanna HI 2215

Notes: The prices from the Carl Roth website cannot be linked to direct. Search for the product code instead. Machine makers like to inflate their numbers by giving the instrument precision excluding the additional error of the electrode and the buffer solutions they provide.

Notes

  • Handheld pH meters like the pHep have a porous ceramics barrier around the electrodes that can clog up disabling the pH meter.
  • Even for tabletop pH meters the electrodes are not very durable. Common problems are breakage, leaking, and drying.
  • Most electrodes need to be stored in 3M KCl. You can buy it or make your own.

See also

pH related protocols on OpenWetWare

Personal tools