Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Dextran Gel G Series Instructions for Use

1. Chemical and Physical Properties

Dextran Gel is a beaded gel containing a large number of hydroxyl groups, allowing it to swell readily in water and electrolyte solutions. The hydrophilic matrix minimizes non-specific adsorption and provides high recovery rates during biomolecule separation. G-type Dextran Gels have varying degrees of cross-linking, resulting in different swelling degrees and fractionation ranges. The swelling degree of Dextran Gel is essentially unaffected by the presence of salts or detergents.

2. Product Specifications

3. Usage Instructions

Sephadex series products are supplied as dry powders and must be swollen before use. Avoid excessive stirring during swelling as it may damage the packing material. Do not use magnetic stirrers.

3.1 Packing Material Preparation

(1) Swell the packing material in an excess of deionized water or buffer at room temperature for 24 hours, or in hot water for 1 hour (Not in a water bath!). The elution buffer should not contain high-viscosity reagents. If floating matter appears on the upper layer during swelling, remove it.

(2) Equilibrate the swollen packing material and all buffers to the experimental operating temperature. Degas all buffers.

3.2 Column Packing

(1) Inspect all column components, especially the filter screen, sealing ring, and screw plug for tightness. Ensure the glass tube is clean and intact.

(2) Wet the column interior and bottom end with water or buffer, maintaining a small liquid level. Ensure no air bubbles are present at the bottom.

(3) Use a glass rod to guide the slurry into the column along the inner wall in one continuous pour, avoiding bubble formation. Open the column outlet to allow the gel to settle freely within the column. Connect the top column end fitting securely.

(4) Start the peristaltic pump and allow buffer to flow through the column at 1.33 times the operating flow rate to stabilize the bed (Ensure pressure does not exceed the maximum pressure resistance of the packing material).

3.3 Equilibration

Equilibrate the column with at least 5-10 column volumes (CV) of buffer before sample application until the recorder baseline stabilizes (i.e., the pH and conductivity of the effluent equal those of the application buffer).

3.4 Sample Application

Samples must be centrifuged or filtered (0.45 µm filter) before application.

For gel filtration, the sample volume is generally no more than 5% of the bed volume. For initial runs, it is recommended to load 1-2% of the bed volume and adjust based on separation results. For desalting, sample volumes up to 20% of the bed volume can be applied. Column height also affects separation; taller columns provide better resolution but cause higher backpressure and should be avoided if possible. Challenging separations require adequate column height and flow rate control. For desalting, a height-to-diameter ratio of 5:1 is sufficient.

3.5 Elution Method

Elution can be performed using salt-free water or the buffer used during column packing.

3.8 Cleaning In Place (CIP)

Perform CIP after every ten uses to remove precipitated and stubbornly adsorbed proteins. Method: Wash with 0.1 M NaOH for 2 column volumes (CV), followed by regeneration with at least 10 CV of equilibration buffer.

4. Storage

Untreated Packing Material: Store sealed at room temperature.

Used Packing Material: Thoroughly rinse out salts with pure water. Finally, store in 20% ethanol at 4°C.

5. Precautions

a) Before sample application, samples must be membrane-filtered and decolorized. Otherwise, impurities and pigments may adsorb onto the packing material, affecting its performance. All buffers must be filtered through a 0.45 µm filter.
b) Avoid using high concentrations of strong acids or bases during operation. Acid and alkali concentrations should be below 0.1 M. Alkali solutions can reduce flow rates.
c) Adsorption and elution methods differ for different samples. Consult relevant literature for specific protocols.

6. Particle Size Specifications

Fine Particles: Slow flow rate, optimal separation resolution.

Coarse Particles: Fast flow rate, reduced separation resolution.

Medium Particles: Moderate flow rate, moderate separation resolution. This type is most commonly selected by customers.