WelPacker DAC Packing Guide
Dynamic Axial Compression Columns (DAC) are commonly used in preparative liquid chromatography and are popular among users due to their significantly longer lifespan compared to conventional static columns. But how do you properly pack a DAC?
In this article, we'll take the WelPacker 50mm DAC as an example to share some tips and tricks from Welch Materials' service engineers, based on their extensive experience in DAC packing.
WelPacker DAC 50mm Dynamic Axial Compression Columns
1. Calculating the Packing Material Quantity and Slurry Volume
Packing Material Quantity Calculation:
V=3.14×r2×h
(V = 3.14 \times r^2 \times h)
- r : Internal radius of the column (cm)
- h : Column packing height (cm)
m=ρ×V
（m = ρ \times V）
- ρ : Bulk density of the packing material (g/mL)
- V : Column packing volume (mL)
Since the packing material becomes more compact after packing, the actual amount of packing material M is approximately 1.1 times the calculated value m. For example, with a 10 μm C18 packing material, if the bulk density is 0.56 g/mL, approximately 300 g of packing material is required to pack a 50 mm DAC with a column bed height of 250 mm.
Slurry Volume Calculation:
Isopropanol is the most commonly used slurry solvent. The volume of slurry solvent is typically twice the mass of the packing material. For instance, 300 g of packing material would require about 600 mL of slurry solvent for proper mixing.
2.Cleaning and Preparation of DAC Hardware
Proper preparation and cleaning before column packing are crucial as they directly impact the performance of the DAC.
Key steps include:
➯ Cleaning the Inner Wall of the Column: The inner wall should be cleaned to remove oil, dust, and other contaminants, ensuring a smooth surface.
➯ Ultrasonic Cleaning of Frits: The frits should undergo ultrasonic cleaning to ensure they are clean and free from blockages.
➯ Cleaning Other Components: Parts that come into direct contact with the mobile phase, such as distributors, seals, and tubing, should also be cleaned beforehand to prevent contamination of the packing material.
➯ Drying: All cleaned components should be thoroughly dried.
Diagram of Accessories and Tools
3. Packing Material Slurry Preparation
Important Considerations for Slurry Preparation:
➯ Choose an Appropriate Slurry Container: Select a container made of inert material, ensuring the total volume of the slurry does not exceed 2/3 of the container's capacity.
➯ Ultrasonic Mixing: It is recommended to stir the slurry while applying ultrasonic treatment for more than 30 minutes (Note: Some fragile packing materials should not undergo ultrasonic treatment).
4. DAC Column Installation Steps
5. Packing the Column
Pour in the slurry and compact the packing material
After pouring in the slurry, it’s necessary to:
Clean the Column Wall: Use isopropanol to wash off any residual packing material from the column wall and rinse the piston.
Adjust the Pressure: Set the air pressure to the final packing pressure.
Remove Air and Excess Slurry: First, expel the air from the top end of the column, then press the slurry out from the bottom end. When no more slurry exits from the bottom end, the packing is complete.
Stabilize and Replace Residual Slurry: Allow the column to stabilize for 30 minutes, then replace the remaining slurry with methanol (or n-hexane) to clean out any residual slurry.
Key Points:
Ensure that all steps are completed as quickly as possible under correct conditions to prevent any adverse effects from packing material settlement.
Welch Materials offers DACs with inner diameters ranging from 25 mm to 800 mm, with customization available according to your needs.