Biological buffers are often used in biological experiments. There are many types of buffers. The buffers you need may match the surface of the buffers you choose. There are certain differences in actual use, so it is very important to choose a suitable buffer. It is necessary; at the same time, different buffers vary greatly. Desheng takes you to talk about the difference between Tris-HCl buffer and HEPES buffer. To
Tris-HCl buffer
Tris buffer is a buffer that is widely used in biochemical research. It is a weak base and the effective pH is commonly used in the "neutral" range. Tris-HCl buffer: pH=7.5～8.5; Tris-phosphate Buffer: pH=5.0～9.0.
Advantages of Tris-HCl buffer
1. Tris-HCl buffer is stable and has good compatibility with physiological body fluids (Tris-HCl does not form precipitation with calcium and magnesium ions; on the contrary, phosphate and calcium and magnesium ions will produce precipitation);
2. In addition, the ionic strength of Tris-HCl buffer at the same pH and the same concentration is low, which is particularly important for enzyme determination, because high ionic strength can easily cause some enzymes to inactivate. Therefore, sometimes using Tris-HCl instead of phosphate buffer, the effect is better.
Disadvantages of Tris-HCl buffer:
1. Great temperature effect, such as pH=8.4 at 4℃, pH=7.4 at 37℃
2. The pH value is greatly affected by the concentration of the solution. If diluted ten times, the change in pH value is greater than 0.1;
3. It has a certain interference effect on some pH electrodes, so an electrode compatible with Tris solution should be used.
4. It is easy to absorb CO2 in the air, so the prepared buffer should be tightly sealed. To
HEPES buffer
HEPES is a non-ionic amphoteric buffer with good buffering capacity in the pH range of 7.2 to 7.4. It is commonly used in biochemical diagnostic kits, DNA/RNA extraction kits and PCR diagnostic kits.
Advantages of HEPES buffer:
The pKa value is between 6.0 and 8.0;
Has high solubility in water;
With membrane impermeability, it is difficult to penetrate biological membranes;
It has limited impact on biochemical reactions, is resistant to chemical and enzymatic hydrolysis, and does not form complexes or precipitates with metal ions;
Very low absorption of visible light and ultraviolet light;
Ion concentration, solution composition and temperature have little effect on dissociation;
Disadvantages of HEPES buffer:
If the HEPES water solution is exposed to ambient light for three hours, it will produce cytotoxic H2O2;
The HEPES water solution must be kept away from light so as not to affect the experimental results;
After being configured as a solvent, it should be stored at 4°C, and it is recommended to use it in a short period of time for better results;
The HEPES powder is generally placed in a dry room when placed, and cannot be exposed to direct sunlight for a long time.