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The Phoenix™ Diffusion Cell improves ease of use, durability, and versatility in comparison to conventional hand-blown vertical diffusion cells. Unlike water-jacketed systems, Phoenix cells operate using dry heat, eliminating the need for water circulation. This enables construction from heavy-duty borosilicate glass with tight dimensional tolerances.
The system simplifies sampling through extract-and-replace operation via a large-diameter sampling arm opening, which accommodates standard pipette tips (approx. 300 μL). This reduces both training requirements and operational complexity.
What improves mixing and test consistency?
The system reduces variability and improves reproducibility in diffusion testing. Special grooves machined into the tops and sides of the mixer inserts promote strong circulation and near-instant homogenization of the cell contents. This helps prevent localized areas of higher API concentration beneath the membrane, reducing variability in results.
How is test preparation simplified?
Phoenix diffusion cells are suitable for quick setup and straightforward operation. You can apply dosage forms through an easily accessible opening in the cell cap, and there’s no need for clamps. You can easily remove air bubbles by lifting and gently tilting the cell.
Slotted evaporation caps help prevent media loss while still allowing manual pipette sampling or autosampling via probe.
Materials and chemical compatibility
The Phoenix system uses chemically resistant materials depending on the configuration:
- Press-on style cell caps are made from PEEK and sealed with Viton™ O-rings
- Threaded style cell caps are made from PTFE and sealed with either Viton or Kalrez™ O-rings for higher resistance to aggressive solvents such as THF and DMSO
Individual serial number
Each diffusion cell, mixer, and cell cap has an individual serial number. This improves traceability and supports better process control throughout testing workflows.
Test parameters
The Phoenix platform provides a broad range of diffusion testing configurations. It includes three diffusion cell sizes, short and tall mixer inserts, and multiple interchangeable cap designs.
Typical operating ranges include:
- Receptor media volumes: 10 mL to 30 mL
- Dosage volumes: 0.25 mL to 6.3 mL
- Orifice diameters: 9 mm to 20 mm
| Diffusion Cell size | Receptor media volume* | Orifice diameters | Dosage chamber volume* |
|---|---|---|---|
| Small | • 10 mL • 13 mL |
• 9 mm • 11.3 mm |
• 0.25–2.0 mL |
| Medium | • 15 mL • 21 mL |
• 11.3 mm • 15 mm |
• 0.40–3.5 mL |
| Large | • 20 mL • 30 mL |
• 15 mm • 20 mm |
• 0.71–6.3 mL |
* Volumes shown are nominal; actual volumes will vary and are determined by measurement of each specific diffusion cell assembly in the lab.
How is diffusion cell design optimized?
The Phoenix system minimizes variability arising from instrument design, procedure, and operator handling. Built on more than 30 years of experience in manual and automated diffusion cell systems, it aims to improve both precision and durability.
Each borosilicate glass cell is manufactured from precision-bore tubing, ensuring consistent internal dimensions across units. The 9 mm internal diameter sampling arm supports rapid homogenization and allows use of standard pipette tips, reducing consumable costs. Standard 16 mm evaporation caps fit securely onto the flanged sampling arm end.
Key design characteristics include:
- Durable, portable construction with easy assembly and cleaning
- Interchangeable cell cap kits compatible with all cell sizes
- Fill mark to indicate correct receptor media level at membrane height
Receptor Media Volume Adjustment
Receptor media volume is adjustable by selecting different mixer inserts:
- Short mixer insert (13 mm): provides maximum receptor volume for a given cell size
- Tall mixer insert (30 mm): reduces volume while maintaining sampling from the central cell body, in line with USP <1724> Semisolid Drug Products—Performance Tests
