Persedex G-25M

Persedex G-25M is the medium grade of the Persedex G-25 series, a range of cross-linked dextran-based gel filtration SEC resins that take advantage of molecular weight differences to separate molecules. The series comprises four grades that differ in particle size, designated C, M, F and SF from coarsest to finest. G-25M sits between the coarse and fine grades in particle size. These resins are used successfully for desalting a wide range of biomolecules, for buffer exchange, and for the separation and purification of small molecular substances such as peptides.

Persedex G-25 has excellent scale-up capabilities:

• A cross-linked dextran matrix with reliable rigidity.
• A range of packaging specifications to meet the processing needs of different sample volumes, allowing straightforward linear scale-up.

Method of use

Chromatographic conditions

Buffer selection. Consider the stability of the sample in the buffer. To avoid possible non-specific adsorption, use a salt-containing buffer rather than ultrapure or pure water.

Flow rate. Generally select a linear flow rate no higher than the recommended 150 cm/h, according to the height of the column bed.

Sample pretreatment. Filter the sample through a 0.45 µm microporous membrane before loading to prevent the sample from clogging the column.

Chromatography steps

1. Equilibration. Use the buffer to fully equilibrate the chromatography column until the pH and conductivity are stable and basically the same as the equilibration buffer. This step usually requires 1–2 column bed volumes (CV).
2. Sample loading. The usual loading volume is 1%–5% of the column volume. The sample concentration should not be too high, to avoid overpressure or affecting the resolution.
3. Elution. Use buffer elution to collect peaks at different positions, usually 1~1.5 CV.
4. Regeneration. Rinse the column with a buffer containing high salt (such as 1M NaCl).
5. Re-equilibration. Re-equilibrate the column with buffer.

Cleaning and regeneration

Contaminants (e.g. lipids, endotoxins and proteins) accumulate on the column as the number of uses of the chromatography resin increases. Regular cleaning-in-place (CIP) is essential to keep the column in a stable working condition. Determine the frequency of CIP according to the degree of contamination of the chromatography resin. Where contamination is considerable, CIP after each use is recommended to ensure repeatability of results and to prolong the working life of the chromatography resin.

For different types of impurities and contaminants, the recommended cleaning conditions are as follows:

• Strongly binding proteins: wash with 5 CV of 2M NaCl solution, or use a high salt buffer not lower than pH 2, such as 1M NaAc solution.
• Strongly hydrophobic proteins and precipitated proteins: first wash with 5 CV of 0.2M NaOH solution, then wash out the lye with 5–10 CV of ultrapure or pure water.
• Lipoproteins and lipids: first wash with 5 CV of 70% ethanol or 30% isopropanol, then rinse with 5–10 CV of ultrapure or pure water.

Degas 70% ethanol or 30% isopropanol before use. The flow rate should be no more than 30–60 cm/h during CIP. Use reverse cleaning where the clogging is severe. To reduce the microbial load, treat the chromatography resin with 0.2M NaOH solution for 30–60 minutes.

Storage

Keep the unopened chromatography resin in the original container and store at 4~30°C in a well-ventilated, dry and clean place. Do not freeze. Wash the used column with 2–3 CV of 20% ethanol solution and store at 2~8°C.

Destruction and recycling

Since chromatography resin is difficult to degrade in nature, it is recommended that the discarded chromatography resin is incinerated to protect the environment. For chromatography resin that has been in contact with biologically active samples such as viruses and blood, follow the local biosafety requirements before destroying or disposing of it.

Packing method

Detailed information on resin packaging is available on request. Please contact your local distributor.

Ordering information

• 573-00100 — 100 ml
• 573-00500 — 500 ml
• 573-01000 — 1 L
• 573-05000 — 5 L