In biochemical experiments or tests, almost all reactions need to be controlled within a certain pH range, especially those involving enzymes. PH changes have a greater impact on the reaction, so biological buffers are used to maintain the pH value of the reaction environment. In biochemical experiments, many of them simulate the detection reaction in the organism, which also requires high pH. Biological body is regulated by humoral fluid, so biological buffer is needed in the experiment.
There are many types of biological buffer, and the preparation methods are somewhat different, but the principle is generally the same. Sodium hydroxide is usually added to the conjugate acid or hydrochloric acid is added to the conjugate base. Both methods can form a buffer solution with sufficient concentration of conjugate acid-base pairs. Here is the preparation method of a small amount (about 1-2l) of dihydroxyethylglycine Bicine or hydroxyethylpiperazine propionic acid EPPS:
Preparation of Bicine buffer
(1) 0.1M solution (A): Bicine 16.317g/ deionized water 1,000ml
(2) 0.1m NaOH solution (B):NaOH 4g/ deionized water 1,000ml
(3) the pH 5.1 1000 ml + 0 ml (B) (A) (A) : (B) = 5-0
PH 7.8 + 200 ml 1000 ml (A) (B) (A) : (B) = 5 to 1
PH 8.2 + 400 ml 1000 ml (A) (B) (A) : (B) = 5-2
PH 8.6 + 600 ml 1000 ml (A) (B) (A) : (B) = o
PH 10.4 + 800 ml 1000 ml (A) (B) (A) : (B) = five
Preparation of EPPS buffer
(1) 0.1M solution (A): EPPS 25.233g/ deionized water 1,000ml
(2) 0.1m NaOH solution (B):NaOH 4g/ deionized water 1,000ml
(3) the pH 5.2 1000 ml + 0 ml (B) (A) (A) : (B) = 5-0
PH 7.3 + 200 ml 1000 ml (A) (B) (A) : (B) = 5 to 1
PH 7.8 + 400 ml 1000 ml (A) (B) (A) : (B) = 5-2
PH 8.2 + 600 ml 1000 ml (A) (B) (A) : (B) = o
PH 8.8 + 800 ml 1000 ml (A) (B) (A) : (B) = five
It should be noted that: the preparation temperature is controlled at 20 degrees. If accurate pH value is needed, it can be measured with A pH meter, and then the proportion of solution A and solution B can be adjusted to A specific pH value. If it is necessary to exclude sodium ions in the test environment, it is also possible to replace sodium hydroxide with potassium hydroxide and change the weight according to the corresponding molecular weight.
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