When should a pH meter be standardized to ensure accurate readings?

When should a pH meter be standardized to ensure accurate readings?

• A. Monthly
• B. Weekly
• C. Before each use
• D. Once

Answer: (C)

pH meters drift and change value between uses, so you must calibrate them every time you take a measurement. The electrode response can shift because of aging, fouling, storage conditions, and changes in the sample matrix or temperature. Calibrating with known buffer solutions right before you measure sets the meter’s slope and offset to reflect the electrode’s current condition, ensuring accurate readings for that sample in its actual temperature. If you wait (monthly, weekly, or even just once), the calibration may no longer represent how the electrode is behaving, leading to biased results. Calibrate before each use to maintain trustworthy pH readings.

pH meters drift and change value between uses, so you must calibrate them every time you take a measurement. The electrode response can shift because of aging, fouling, storage conditions, and changes in the sample matrix or temperature. Calibrating with known buffer solutions right before you measure sets the meter’s slope and offset to reflect the electrode’s current condition, ensuring accurate readings for that sample in its actual temperature. If you wait (monthly, weekly, or even just once), the calibration may no longer represent how the electrode is behaving, leading to biased results. Calibrate before each use to maintain trustworthy pH readings.