List of buffer solutions | (Preparation Method for specific pH)

A buffer is a combination of strong acid and its basic salt or a strong base and its acidic salt.

These buffer solutions are used to regulate the pH of a solution.

Enzyme reactions are sensitive to pH changes, so buffers become essential to maintain a stable pH.

The list of buffer solutions

The buffers can be listed as standard buffers and also specific buffers

Standard buffers are

1. Hydrochloric acid buffer
2. Acid phthalate buffer
3. Phthalate buffer
4. Phosphate buffer
5. Alkaline borate buffer.

Specific buffers include

1. Acetate buffer
2. Acetic ammonia buffer
3. Acetone buffer
4. Ammonia buffer
5. Barbitone buffer
6. Buffered Copper sulfate solution
7. Glycerin solution
8. Glycine buffer solution
9. Imidazole buffer
10. Palladium chloride buffered solution
11. Phosphate buffer (mixed)

• Standard buffers are the solutions that have a standard pH.

• They are used as reference standards for the measurement of pH.

• They are also used for chemical tests that need maintenance of specific pH.

• These standard buffers can be modified to regulate varying degrees of pH with appropriate combinations of solutions.

Hydrochloric acid buffer is prepared by a combination of the hydrochloric acid solution with a potassium chloride solution.

Hydrochloric acid (0.2M)

Hydrochloric acid is diluted with freshly boiled and cooled water to get 1000ml 7.292 g of HCl.

Potassium chloride (0.2M)

14.911 g of potassium chloride is dissolved in water and made to 1000ml.

pH	The volume of 0.2M HCl in ml required
1.2	85.0
1.3	67.2
1.4	53.2
1.5	41.4
1.6	32.4
1.7	26.0
1.8	20.4
1.9	16.2
2.0	13.0
2.1	10.2
2.2	7.8

Acid Phthalate buffer

• Take 50ml of 0.2M potassium hydrogen phthalate solution into a 200 ml volumetric flask.

• Then add below the mentioned volume of hydrochloric acids and make up the final volume with water.

pH	Vol of 0.2M HCl (mL) to be used
2.2	49.5
2.4	42.2
2.6	35.4
2.8	28.9
3.0	22.3
3.2	15.7
3.4	10.4
3.6	6.3
3.8	2.9
4.0	0.1

Neutralized phthalate buffer

• Into a 200ml volumetric flask, take 50ml of 0.2M Potassium hydrogen phthalate solution.

• Then add the mentioned volume of 0.2M sodium hydroxide solution and make up the final volume with water.

pH	Volume if 0.2M NaOH (ml)
4.2	3.0
4.4	6.6
4.6	11.1
4.8	16.5
5.0	22.6
5.2	28.8
5.4	34.1
5.6	38.8
5.8	42.3

Phosphate buffer:

• Take 50ml of 0.2M of potassium dihydrogen phosphate solution into a 200ml flask.

• Then add 0.2m NaOH solution of defined volume in the table. Make up the final volume with water and shake the flask well.

pH	Volume of 0.2M NaOH (mL)
5.8	3.6
6.0	5.6
6.2	8.1
6.4	11.6
6.6	16.4
6.8	22.4
7.0	29.1
7.2	34.7
7.4	39.1
7.6	42.4
7.8	44.5
8.0	46.1

Alkaline borate buffer:

• Add 50ml of 0.2M boric acid and 0.2M potassium chloride in a 200ml volumetric flask.

• To this mixture add a specified volume of 0.2 M NaOH and makeup to the final volume.

pH	Volume of 0.2N NaOH (mL)
8.0	3.9
8.2	6.0
8.4	8.6
8.6	11.8
8.8	15.8
9.0	20.8
9.2	26.4
9.4	32.1
9.6	36.9
9.8	40.6
10	43.7