Pure Water and Ultrapure Water pH Measurement-glass Electrode Method

Release Time

2021-09-15 00:00


1.Background introduction

Pure drinking water, engine cooling water, boiler feed water and other pure water or ultrapure water samples have clear requirements for water quality pH. When the pH deviates from the normal range, it often means that the water quality deteriorates and the equipment may be damaged.

Compared with buffer solutions and conventional samples, the pH measurement of ultrapure water and pure water is often more difficult. Because pure water ionizes few ions and high resistance, ordinary pH electrodes will have problems such as slow response, drift of indication, poor repeatability, low accuracy, and short life during the measurement process. The main reason for this situation is that the traditional reference structure has unstable potential in pure water test applications, requires a long time to balance, and is prone to liquid junction potential errors. On the other hand, ordinary electrodes have large internal resistance and slow response, making it difficult for the electrodes to reach equilibrium.

The REX 962221 ultrapure water pH composite Electrode is tailor-made for ultra-low conductivity samples. The structure adopts a long-life reference system and a multi-stage reference structure to reduce the error of pure water pH testing; adopts a high-precision glass grinding port to optimize the flow rate design; adopts an optimized low-resistance sensitive membrane for faster response. This makes the pH test of pure water samples faster, more stable and more accurate.

Pure Water and Ultrapure Water pH Measurement-glass Electrode Method

2.Determination of pH value of pure water and ultrapure water sample

In this experiment, REX 962221 ultrapure water Ph Composite Electrode (A), a well-known foreign brand pure water special PH Electrode (B) and conventional electrode E-201-C pH composite electrode (C) were used to test drinking pure water and Ultrapure water sample.

Before the test, the electrode was activated in 3M KCl solution for 2 hours, rinsed with deionized water, and inserted into pH 4.01 and pH 9.18 standard solutions for calibration. Set the instrument parameters, put the electrode in freshly prepared ultrapure water or other water samples, read the data every 5 seconds, and record the readings

After several tests of drinking purified water, the following data chart is obtained. Comparing the test results of 3 electrodes, it can be seen that after more than two hundred seconds, the REX 962221 ultrapure water pH composite electrode (A) and a well-known foreign brand pure water Ph Electrode (B) The pH data of E-201C tends to be stable, maintaining 6~7 pH; the pH value of the conventional E-201C electrode (C) has been getting smaller and it is difficult to stabilize.

The same applies to the test of ultrapure water, the measurement result of the ultrapure water electrode also tends to be stable after two to three hundred seconds. The pH of the obtained ultrapure water is maintained between 5.80 and 6.00.

Pure Water and Ultrapure Water pH Measurement-glass Electrode Method