“The pH meter is an instrument for measuring the pH of a solution. The main body of the pH meter is a precision potentiometer. When measuring, insert the composite electrode into the measured solution, and different electromotive force will be generated due to the different acidity (hydrogen ion concentration) of the measured solution, which will be amplified by the DC amplifier, and finally the measured solution will be pointed out by the reading indicator (voltmeter) The pH value. The pH meter can be used in the range of 0-14pH. There are many types of acidity meters, such as desktop, portable, and meter types, and the reading indicator has two types: digital and pointer.
①Calibration: First adjust the slope regulator of the instrument to the 100% position, and then adjust the temperature regulator to the temperature value according to the temperature of the measured solution.
② Positioning: Insert the composite electrode into the instrument. Choose a buffer solution that is closest to the pH of the sample, put the electrode in this buffer solution, and shake the laboratory beaker to make the solution uniform. After the reading is stable, the reading should be the pH value of the buffer solution, otherwise the positioning regulator must be adjusted. When used for determinations with high analytical accuracy requirements, two buffer solutions should be selected (that is, the pH value of the sample to be tested is between or close to the pH values of the two buffer solutions). After the pH reading of the first buffer solution is stable, the reading should be the pH value of the buffer solution, otherwise adjust the positioning regulator. Clean the electrode and absorb the remaining liquid on the surface of the electrode bulb. Put the electrode in the second buffer solution, shake the beaker to make the solution even, after the reading is stable, the reading should be the pH value of the second buffer solution, otherwise adjust the slope regulator.
③Measurement: The pH-calibrated instrument can be used to determine the pH value of the sample. At this time, the temperature regulator, positioning regulator, and slope regulator can no longer be moved. Wash the electrode with distilled water, dry the ball of the electrode with filter paper, insert the electrode into the lab borosilicate beaker containing the sample to be tested, gently shake the glass beaker, and after the reading is stable, the pH value of the sample to be tested will be displayed. The main sensing part of the composite electrode is the electrode bulb. The bulb is extremely thin and must not be in contact with hard objects. After the measurement, put on the protective cap and put a small amount of replenisher (3mol/L potassium chloride solution) in the cap to keep the electrode bulb moist. The instrument adopts CMOS integrated circuit, insert the short-circuit plug when not in use. The soldering iron must be well grounded during maintenance to protect the instrument.
Post time: Dec-17-2021
