Preparation of 20% (w/v) Sodium Dodecyl Sulfate (SDS) Solution

Overview

• Sodium dodecyl sulfate (SDS,  CH₃(CH₂)₁₁OSO₃Na, molecular weight 288.38 g/mole, CAS Number 151-21-3) is an anionic surfactant (detergent) and is used extensively in biological research as a strong protein denaturant and lipid-solubilizing agent.
• It is also used extensively in our cleaning and personal care products, e.g., shampoos, hand soaps, bath products, shaving creams, toothpaste.
• It appears as white to yellowish powder. It is soluble in water. Heating dissolves SDS quickly in water, thus helping to prepare concentrated SDS aqueous solution (20% SDS solution in water). Once dissolved, SDS forms a clear transparent, or slightly yellowish solution.
• A 10% or 20% (w/v) stock solution of Sodium dodecyl sulfate (SDS) is generally prepared in distilled water (or Milli Q water). Since SDS is an ingredient of many solutions, the stock solution of SDS is conveniently used to prepare them. 

Requirements

Reagents
> Sodium dodecyl sulfate (SDS)
> Deionized / Milli-Q water

Equipment and disposable
> Measuring cylinder
> Conical flask / Beaker
> Magnetic stirrer

Composition:
20% Sodium dodecyl sulfate (SDS)

Objective:
Preparation of 100 ml of 20 % Sodium dodecyl sulfate (SDS) in Deionized / Milli-Q water.

Preparation

Step 1: To prepare 100 ml of 20% SDS solution, weigh out 20 g SDS in 250 ml conical flask/beaker. Add 80 ml deionized / Milli-Q water and mix it.

Tip:
One can use manual shaking using a glass pipette to mix the ingredients. The magnetic stirrer makes the dissolving process easy and convenient.

Precaution:
1. Do not dissolve in 100 ml of deionized / Milli-Q water. In most cases, solution volume increases when a large amount of solute dissolves in a solvent.
2. Wear a face mask to avoid inhalation of SDS dust.
3. Try to avoid frothing. If you are using a magnetic stirrer, keep the speed low to avoid frothing.

Step 2: Heat to 68 °C if necessary.

Tip:
One can set the magnetic stirrer temperature 68 °C. If a magnetic stirrer is unavailable, place the solution in a water bath set at 68 °C.

Precaution:
Make sure to dissolve any residual powder sticking to the glass.

Step 3: Adjust the volume to 100 ml with deionized / Milli-Q water. Mix it again.

Note:
Autoclaving is not required for a 20% SDS solution.

Storage
The solution can be stored at room temperature for several months.

Precaution:
Do not store the solution at 4 °C. SDS will precipitate at temperatures below 15 °C. If there is any precipitate, re-dissolve by warming the solution (68°C for 10 min)

Applications
> Plasmid isolation by alkaline lysis method
> SDS-PAGE electrophoresis
> Preparation of Laemmli sample buffer
> Stripping of immunoblot