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Q: Why does the term 'pH' mean?
A: In chemistry, pH is a numeric scale used to specify the acidity or alkalinity of an aqueous solution. It is the negative of the logarithm to base 10 of the activity of the hydrogen ion. Solutions with a pH less than 7 are acidic and solutions with a pH greater than 7 are alkaline or basic. Read more... (extract from Wikipedia)
Q: How long does a pH electrode last?
A: The life of a pH electrode is quite variable, and depends on several factors including, frequency of use, testing conditions, cleaning and storage techniques. Having said that, a pH electrode typically has a six month warranty, and a typical life is 18 months. Electrodes are knownto fail after one year, but may last more than two years. These numbers are anicdotal and are not intended to be manufacturer's specifications.
Q: Which is the correct term - pH electrode or pH probe?
A: The term 'probe' is typically kept for simple devices such as temperature and conductivity sensors. pH sensors are called electrodes because a chemical reaction is taking place inside the body of the sensor, which is proportional to the ionic activity of the Hydrogen ions in the testsolution. The complexity of the chemical reaction is largely the reason for the short life of the pH electrodes as compared to temperature and conductivity probes.
Q: What tips can you give for pH buffer use?
A: These solutions of known pH value allow the user to calibrate the pH meter to make accurate measurements.
For the highest accuracy:
Q: How can I get reliable pH measurements?
A: Here are some basic steps that will help you get better, more reliable pH measurements:
Q: What is automatic temperature compensation (ATC)?
A: The Solution Temperature Effect
When there is an increase or decrease in the temperature of a solution, the pH of the solution can change. This change is not an error caused by the variation in temperature; it is the true pH of the solution at the new temperature. Since this is not an error, there is no need to correct orcompensate for the solution temperature effect.
There is only one major temperature effect in pH measurement that can cause errors in readings. This is the change in the electrode's response (or sensitivity) to pH which results from changes in the samples temperature. It is the only reasonably predictable error due to changes intemperature, and is the only temperature related factor that pH instruments with temperature compensation can correct for. This temperature error is very close to 0.003 pH/°C/pH unit away from pH 7. If a sample is measured without using an automatic temperature probe, the solutionstemperature needs to be entered into the meter manually to allow it to account for this error.
Q: How should an electrode be stored when not in use?
A: Electrodes should be stored in electrode storage solution (025 192) between readings and for shortterm storage. If storage solution is not readily available, liquidfilled electrodes can be stored in pH 4.0 buffer solution. To return an electrode to longýterm storage, prepare it inthe same condition in which you received it; usually, this means simply moistening and replacing the end cap of gelfilled electrodes to protect and keep the sensing membrane active. To store liquidfilled reference and combination electrodes, refill with electrolyte, cover the fill hole, andmoisten and replace the protective plastic cap.
Important note: Never store an electrode in distilled or deionised water. This may lead to slow, sluggish response.
Q: How should a pH electrode be cleaned?
A: A dirty glass membrane is usually indicated by beads of water forming on the bulb when it's rinsed with distilled water. The bulb can be cleaned as follows: