Overview:
TB salt solution is nothing but a potassium phosphate buffer. A 10x TB salt solution contains 170 mM Potassium phosphate monobasic (KH2PO4) and 720 mM Potassium phosphate dibasic (K2HPO4). It can be prepared by dissolving 23.135 g of KH2PO4 (Molecular Weight: 136.09) and 125.41 g of K2HPO4 (Molecular Weight: 174.18) in water to a final volume of 1L. The solution is sterilized by autoclaving.
In the following section, we describe a procedure to prepare 250 ml of 10X TB salts.
REQUIREMENTS
Reagents and solutions
Potassium phosphate monobasic (KH2PO4)
Potassium phosphate dibasic (K2HPO4)
Equipment and disposables
Measuring cylinder
Conical flask / Beaker
Composition
170 mM Potassium phosphate monobasic (KH2PO4)
720 mM Potassium phosphate dibasic (K2HPO4)
Objective
Preparation of 250 ml of 10X TB salts
PROCEDURE
Step 1: To prepare 250 ml of 10x TB salts, weigh out 5.78g KH2PO4 (Molecular Weight: 136.09) and 31.35 g of K2HPO4 (Molecular Weight: 174.18) in a 250 ml conical flask/beaker. Add ≈ 200 ml deionized/Milli-Q water and mix until dissolved completely.
Tip:
One can use manual shaking using a glass pipette to mix the ingredients. Magnetic stirrer makes the dissolving process easy and convenient.
Precaution:
Do not dissolve in 250 ml of deionized / Milli-Q water. In most cases, solution volume increases when a large amount of solute is dissolved in a solvent.
Step 2: Adjust the volume to 250 ml with deionized / Milli-Q water. Mix it again.
Step 3: Sterilize the solution by autoclaving (20 minutes at 15 lb/sq.in. (psi) from 121-124°C on liquid cycle).
Storage
The solution can be stored at room temperature.
| Follow the table to prepare 10X TB salt of various volumes (100, 250 ml, 500 ml, and 1000 ml) | ||||
| Solution concentration / Volume | 100 ml | 250 ml | 500 ml | 1000 ml |
| KH2PO4 | 2.31 g | 5.78 g | 11.67 | 23.135 g |
| K2HPO4 | 12.54 g | 31.35 g | 62.7 g | 125.41 g |
