Preparing salt solutions (150 mM and 128 mM) using a LevMixer™ System
The LevMixer™ system is a compact and non-invasive single-use mixing system. The heart of this system is a mixing biocontainer incorporating a bottom-mounted levitating impeller designed for powder-liquid and liquid-liquid mixing applications. The impeller is frictionless and generates no particles.
Powder-liquid mixing is a common requirement in biopharmaceutical processing. In order to maximize mixing efficiency for powder-liquid applications, a variant of our LevMixer system is available with a large 16.13 cm (6.35 inch) centrally located impeller.
In this application note we describe LevMixer system methods used to prepare:
- 160 L of a typical buffer solution
- 400 L of a typical buffer solution
Materials and methods
160 L buffer prepared in a 200 L LevMixer system (150 mM NaCl solution)
A 200 L LevMixer mixing biocontainer was filled with 160 L of water and the mixing speed was set to 180 rpm. In total, approximately 1.4 kg of sodium chloride (NaCl) powder was added to the mixing biocontainer, resulting in a 150 mM solution. The NaCl additions were made in three increments, each approximately 500 g, at t = 0 min, t = 3 min and t = 6 min. Solution homogeneity was monitored via real-time conductivity readings after each addition.
400 L buffer prepared in a 500 L LevMixer system (128 mM NaCl solution)
A 500 L LevMixer mixing biocontainer was filled with 400 L of water and the mixing speed was set to 180 rpm. In total, 3 kg of sodium chloride (NaCl) powder was added to the mixing biocontainer, resulting in a 128 mM solution. The NaCl additions were made in three increments, each 1000 g, at t = 0 min, t = 6 min and t =12 min. Solution homogeneity was monitored via real-time conductivity readings after each addition.
Results
Figure 1 shows solution homogeneity in the 200 L biocontainer during mixing. After each NaCl powder addition, mixing was found to be 95% complete within 30 s, and 100% complete within 90 s.
Fig 1. Solution homogeneity in the 200 L LevMixer system during mixing.
Figure 2 shows solution homogeneity in the 500 L biocontainer during mixing. After each NaCl powder addition, mixing was found to be complete within 240 s.
Fig 2. Solution homogeneity in the 500 L LevMixer system during mixing.
Conclusion
Our LevMixer™ system is well suited for preparation of buffer salt solutions. This mixing system includes a large, centrally mounted, levitated impeller, and is a good choice for powder-liquid mixing applications.
In these experiments we found:
- Mixing times in the sub-240 s range are typical at the tested volume (400 L) and salt concentration (128 mM).
- Mixing times in the 60-90 s range are typical at the tested volume (200 L) and salt concentration (150 mM).
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