Can pH meter temperature compensation eliminate all temperature-induced errors?
It must be pointed out that the temperature compensation set on the pH meter is only the slope item (2.303RT/F) of the compensation electrode. Also affected by the temperature are the standard potential of the glass electrode, the liquid junction potential, etc., which are not strictly linear with the temperature. At the same time, the pH electrode also needs a certain amount of time to reach equilibrium at the new temperature. Therefore, neither manual temperature compensation nor automatic temperature compensation is sufficient. According to the operational definition of pH measurement, in order to obtain precise measurement results, the sample solution and the standard solution should be measured at the same and constant temperature, which is the principle of isothermal measurement. For pH measurement with general accuracy requirements, temperature compensation can be used when the temperature of the sample solution is different from that of the standard solution.
How to tell if your pH meter is accurate?
Many users have doubts when using the pH meter. Is this pH meter accurate? Some people judge by work experience, some judge by pH test paper, and some judge by the pH meter used in the past, all of which are unreliable. In fact, the only reliable and easiest method is to use pH standard buffer solution for verification. This is the only test standard. Take three standard buffer solutions: pH 6.86, pH 4.00, pH 9.18 (preferably freshly prepared and at the same temperature), use pH 6.86 for positioning calibration, use pH 4.00 for slope calibration, and then test pH 9.18 to see if the pH meter is accurate, See if you are qualified.
How to clean the pH electrode?
After the bulb and liquid junction are polluted, they should be cleaned with the following solvents, then washed with deionized water to remove the solvent, and then immersed in the soaking solution to activate the electrodes.
(1) Pollutants: ①Inorganic metal oxides, ②Organic grease substances, ③Resin polymer substances, ④Protein hemocyte precipitates, ⑤Pigment substances.
(2) Cleaning agent: ① less than 1 mol/L dilute acid, ② dilute detergent (weak acid), ③ dilute alcohol, ④ acetone, ⑤ ether, ⑥ acid enzyme solution (food raw tablets), ⑦ dilute bleach , ⑧ hydrogen peroxide.
