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PH Meter Regularly Remove The Inner And Outer Layers
Jul 20, 2017

By measuring the electrode and the reference electrode composed of the working battery in the solution measured in the potential difference, and the value of the solution to be measured with the working battery potential between the size of the linear relationship between the current meter and then converted into pH unit value To achieve the determination.

1.pall the storage of glass electrodes

PH meter in the short term when not in use, can be fully immersed in saturated potassium chloride solution. But if long-term do not have to dry it, should not use washing liquid or other water-based reagent immersion.

2.PH glass electrode cleaning

Glass electrode bulb contamination may increase the electrode response time. CCl4 or soap can be used to wipe the dirt, and then immersed in distilled water a day and night to continue to use. When the pollution is serious, can be 5% HF solution for 10 to 20 minutes, immediately rinse with water, and then immersed in 0.1N HCl solution for a day and night to continue to use.

3. Glass electrode aging treatment

The aging of the glass electrode is related to the progressive change of the adhesive layer structure. Old electrode response is slow, film resistance is high, slope is low. Exfoliation of the outer layer with hydrofluoric acid can often improve electrode performance. If this method can be used to regularly remove the inner and outer layers, the electrode life is almost unlimited.

4. Storage of reference electrode

Silver - silver chloride electrode is the best storage solution is saturated potassium chloride solution, high concentration of potassium chloride solution can prevent the silver chloride in the liquid junction precipitation, and maintain the fluid interface in working condition. This method also applies to the storage of composite electrodes.

PH meter, is a commonly used equipment, mainly used to accurately measure the pH value of liquid medium, coupled with the corresponding ion-selective electrode can also measure the ion electrode potential MV value, pH meter is widely used in environmental protection, sewage treatment, scientific research , Pharmaceutical, fermentation, chemical, aquaculture, tap water and other fields.

Because the electrode is aging. The response time of the electrode in the buffer can be tested. If it is greater than 1 minute, it is necessary to activate the electrode or replace the electrode. If the measurement buffer response time is very short, but the measurement sample is unstable, indicating that the electrode is not suitable for measuring the measured sample, according to the electrode selection guide to select the appropriate electrode.

The life of the pH electrode is related to the nature of the sample, the sample temperature and the frequency of use, and the maintenance. In the case of normal use, proper maintenance, pH electrode life of 1 to 2 years.

PH meter instability phenomenon Summary:

① check the electrode is damaged;

② should be used for too long electrode time, first check to see if it is effective;

③ can try under the 2.5mmoL / L KCL solution soak the probe;

④ cleaning glass ball, is not a long time, attached to some of the above organic matter, resulting in reaction is not sensitive;

⑤ there is a chemical level in the water level of CO2 + H2O → H + + HCO3-, due to the general water or surface water are weakly alkaline lead to the balance to the positive reaction direction of the pH will continue to rise;

⑥ Add neutral salt (eg, KCl) to the water sample as the ionic strength modifier, change the total ionic strength in the solution, increase the conductivity, and make the measurement fast and stable. This method of national standard GB / T6P04.3-93 provides: "water samples in order to reduce the impact of liquid potential and quickly stabilized, every 50mL water sample by adding a drop of neutral 0.1moL / L KCl solution." Although this The method changes the ionic strength in the water sample and, to a certain extent, causes its pH to change, but it has been experimentally proved that the change is only about 0.01pH in numerical values and is completely acceptable. However, when using this method, it is important to note that the added KCL solution should not contain any alkaline or acidic impurities. Therefore, KCl reagents to use high purity, the solution with the water quality should be high purity neutral water quality.