Calibration of pH Meter

Following are general calibration procedures for a pH meter. Specific instructions may be found in a help menu in the software of the pH meter or in an accompanying users manual. The more specific instructions should be consulted and followed.

  1. You may calibrate to pH 4, 7, 10 or any combination. You need to calibrate to at least 2 buffer solutions. For best accuracy, calibrate to all 3 pHs at the temperature of the test solution.
  2. Turn on the pH meter using the “ON/OFF” button and press the “CAL” button to enter calibration mode.
  3. Immerse the electrode about 1 inch into the buffer solution in a medicine cup and wait for the displayed value to stabilize. This might be 30 seconds.
  4. Press the “HOLD/CON” button to confirm the calibration at that buffer.
  5. Rinse the electrode with deionized (DI) water and remove excess water.
  6. Repeat procedure using another pH buffer solution(s) to complete the slope adjustments. Buffer solutions may be used for calibration in any order.
  7. Replace the buffer(s) into storage bottles (remember these have to remain pristine solutions and should be separate containers from the stock solution).

pH meter best practices

  • Unless the probe is specialized, it is designed to be used in a liquid fluid. More specifically when a solid, such as soil, is present touching the probe to the soil is to be avoided. Keep the probe in the supernatant above the soil. Touching the probe to the soil damages the probe.
  • Rinse the probe between measurements, but do not touch the probe with anything to dry it.
  • Do not store the probe in distilled deionized water.
  • Throughly rinse the probe prior to storage after use. Typical storage is in pH 4 buffer, but their is good reasons to choose other storage mediums.