Preparation of Stock Solution of Tetracycline (12 mg/ml)


  • Tetracyclines are a group of broad-spectrum antibiotics. They are active against a wide range of microorganisms including bacteria (both gram-positive and gram-negative), chlamydiae, mycoplasmas, rickettsiae, and protozoan parasites.
  • Tetracyclines function by inhibiting protein synthesis.
  • Binding of tetracyclines to 30S ribosomal subunit prevents access of aminoacyl tRNA to the acceptor site on the mRNA – ribosome complex, leading to inhibition of protein synthesis.
  • Tetracycline hydrochloride can be used for biological research.
  • Tetracycline hydrochloride is soluble in water (50 mg/ml) with heating. It forms a clear, yellow to yellow-orange solution in water.
  • It also forms a clear, yellow-green solution in 95% ethanol.
  • Tetracycline is rapidly destroyed by alkali hydroxide solutions and solutions in water become turbid on standing due to hydrolysis and precipitation of tetracycline.
  • The potency of tetracycline is reduced in solutions with pH below 2.
  • A 5 – 12 mg/ml stock solution of tetracycline is generally prepared in 70% ethanol. The stock solution is diluted to the final concentration, depending on the need.
  • Magnesium ions are antagonistic to tetracycline, therefore, don’t use magnesium salt in bacterial culture medium if tetracycline is going to be used for selection. This may lead to false positives.


> Tetracycline hydrochloride (C2H24N2O8.HCl) (Molecular weight: 480.9)
> 70% ethanol

Equipment and disposables
> Measuring cylinder
> Conical flask / Beaker / 15 ml screw-capped tube
> Magnetic stirrer

> 12 mg/ml tetracycline
> 70% ethanol

Preparation of 10 ml of tetracycline stock solution (12 mg/ml) in 70% ethanol


Step 1: To prepare 10 ml of 12 mg/ml tetracycline stock solution, weigh out 120 mg of tetracycline. Transfer it to a 15 ml screw-capped tube. Add 9 ml of 70% ethanol. Mix until all tetracycline dissolves completely.

We recommend using a 15 ml screw-capped tube with milliliter marks. Transfer all the contents in it. Add 9 ml of 70% ethanol and mix the content by rotating the tube. Once the content is mixed, make up the volume to 10 ml.

Do not dissolve in 10 ml of deionized / Milli-Q water. It is always a good practice to dissolve all ingredients first and then adjust the volume to the desired volume with the solvent.

Step 2: Adjust the volume to 10 ml with 70% ethanol. Mix it again.

Store the solution in small aliquots (1 ml) at -20°C for a long time.

Protect the solution from light.

> A selection marker for bacterial culture during gene cloning experiments.
> Often used for inducible expression systems (tet-on tet-off) in mammalian cells.

Was this post helpful?

Author: admin

Leave a Reply

Your email address will not be published. Required fields are marked *