A pH meter is a precision instrument commonly used in laboratories and industrial fields to measure the acidity or alkalinity of solutions. Mastering the correct usage steps and daily maintenance methods can ensure the accuracy of measurement results and extend the lifespan of the instrument.

Correct usage steps

1. Preparation before calibration

Check the status of the electrodes to ensure that there are no cracks or stains on the glass bulb, and that there are no blockages in the liquid contact area of the reference electrode. If using composite electrodes, it is necessary to confirm that the filling solution (such as 3mol/L KCl solution) is sufficient. Clean the electrode with deionized water and dry the surface moisture with filter paper.

2. Two point calibration

Select standard buffer solutions that are close to the pH of the sample (such as pH 4.00, 6.86, 9.18). First calibrate with pH 6.86 buffer solution, immerse the electrode in the solution, stir until the reading stabilizes, and then press the "calibrate" button. The instrument will automatically store the slope and zero point. Repeat the operation with the second buffer solution (such as pH 4.00 or 9.18) to complete the calibration.

3. Sample measurement

Insert the electrode into the solution to be tested, gently stir or shake (to avoid generating bubbles), and record the data after the reading stabilizes. Immediately clean the electrode with deionized water after measurement to avoid cross contamination. If the sample contains protein or oil, the electrode surface residue should be dried with filter paper before cleaning.

Key points of daily maintenance

1. Electrode maintenance

When not in use for a long time, immerse the electrode in a 3mol/L KCl solution for storage to avoid drying. If the electrode is dry, it needs to be soaked in KCl solution for more than 24 hours to restore its performance. Regularly clean the electrodes. If the glass film is contaminated with oil, neutral detergent can be used for cleaning; If the reference electrode is blocked, use fine sandpaper to gently polish the liquid contact area.

2. Instrument storage

The pH meter should be stored in a dry and dark environment, avoiding high temperatures or humidity. Avoid contact with corrosive gases to prevent damage to the circuit board.

3. Regular calibration and inspection

It is recommended to calibrate once a week. If high measurement accuracy is required, it can be calibrated daily. Regularly check the electrode response time and slope. If the slope is below 90%, replace the electrode or supplement the filling solution.

4. Avoid misoperation