| Message: | Tris, or tris(hydroxymethyl)aminomethane, has been widely used as a pH buffer in biological media for about 35 years. The near-ideal properties of this biological buffer are the reason for its popularity. Tris does not absorb water, is easily soluble in water, and has high purity. It does not precipitate calcium salts,
Biochemists use TRIS buffers to control the pH within the physiological range (approximately 7 to 8 pH), because phosphate can cause adverse reactions with biological substances in the test sample. However, when pH measurements are to be made on these solutions, another type of "adverse side reaction" must be recognized, involving the pH electrode system.
The influence of chemical and physical properties of Tris buffer on pH
Tris, which is commonly used for physiological measurement (pH 7 to 7.5), does not have a large buffer capacity. Therefore, caution should be exercised when using tris buffer to control sample pH. The rather large temperature coefficient of tris (-0.028pH/ C) is also worth considering. For example, if the meter is calibrated with tris buffer and the tris temperature is 20 C, using a pH value of 25 C will cause errors.
The temperature effect is large, and the temperature change has a great influence on the pH value of the buffer, so it must be prepared at the use temperature, and the Tris-HCl buffer prepared at room temperature cannot be used at 0 C to 4 C;
It is easy to absorb CO2 in the air, so the prepared buffer should be tightly sealed;
This buffer has a certain interference effect on some pH electrodes, so use an electrode compatible with Tris solution. |
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