Regardless of whether you are a chemist, biologist, environmentalist or laboratory technician, if you want to measure the acid or base potential of a solution, you will have to use a pH meter. This device is very useful and is the most accurate tool for calculating the pH level of a sample. If you want to make sure you get the most accurate reading possible, you will have to follow a few simple steps, such as preparing the necessary materials, and calibrating and testing the device.
Steps
Part 1 of 3: Prepare for Calibration
Step 1. Turn on the pH meter
Before you start calibrating and using the device, you will need to turn it on and give it enough time to warm up. Generally, this can take around 30 minutes, but it is better to check the user manual to confirm the exact time.
Step 2. Clean the electrode
Remove the electrode from the storage solution and rinse it with distilled water in an empty beaker. Once it's done, pat it dry with lint-free cloths. You can usually find Kimwipes or Shurwipes at most office supply stores.
- Make sure to rinse the electrode in a different glass than the one you will use to calibrate the pH meter.
- Be careful not to rub the electrode, as it has a sensitive outer membrane.
- If you think that the electrode is very dirty, check the user manual to find out what type of cleaning solution you can use.
Step 3. Prepare the calibration solutions
Generally, you need more than one solution to calibrate the pH meter. The first should be a pH 7 (neutral) solution and the second should have a pH similar to that of the sample, either 4 or 9, 21. A high pH (9, 21) calibration solution is ideal for measuring a base sample, while a low pH calibration solution (4) is better for measuring an acid sample. Once you choose the most suitable solutions, allow them to reach the same temperature as the meter. This is because the pH level is related to temperature. Pour the solutions into separate beakers to begin the calibration process.
- Contact the manufacturer of your device, or your study or work center, to find out where to get the calibration solutions.
- Solutions should not remain in beakers for more than two hours.
- Once you're done, you can dump the liquid out. Do not return it to the original container.
Part 2 of 3: Calibrate the pH meter
Step 1. Place the electrode in the pH 7 calibration solution and start the measurement process
Once submerged in the liquid, press the "Measure" or "Calibration" button to get a reading of the pH level.
Allow the pH level reading to stabilize and then let it sit for 1 to 2 minutes
Step 2. Mark the pH level
Once the reading stabilizes, press the measure button again to dial the device according to the pH level of the solution. This way, you will get more accurate readings.
While this step is not necessary, if you stir the calibration solution before measuring the level, be sure to do the same for the other solutions and the sample
Step 3. Rinse the electrode with distilled water
Rinse it well and dry it with a lint-free cloth, such as Kimwipes or Shurwipes, before dipping it into another solution.
Step 4. Place the electrode in the appropriate calibration solution according to your sample and start the measurement process
Once it is submerged in the liquid, press the measure button to begin calculating the pH level.
Step 5. Re-dial the pH level
Once the reading stabilizes, press the measure button again to dial the device based on the pH level of the solution.
Step 6. Rinse the electrode
You can use distilled water to make it. Also, dry with a lint-free cloth, such as Kimwipes or Shurwipes, between uses.
Part 3 of 3: Using the pH Meter
Step 1. Place the electrode in the sample and start taking the measurement
Once the electrode is in the sample, press the measure button and allow the device to sit for 1 to 2 minutes.
Step 2. Mark the pH level
Once the reading stabilizes, press the measure button again. As you do so, you will see the pH level of the sample on the device screen.
Step 3. Clean the electrode after use
Rinse the electrode with distilled water and dry it with a lint-free cloth. Once the device is clean and dry, you can put it away.
Check the user manual to find out the best way to store your pH meter
Advice
- If you are not sure about a process, ask the necessary questions. You can speak with the supervisor of the laboratory where you work or review the manual of use of the equipment.
- All pH meters are a little different. Therefore, you'd better review the necessary manuals before you start calibrating and using your device.