Solvents are commonly used prior to lyophilisation because they improve the solubility & stability of certain samples. Many biological and pharmaceutical compounds dissolve poorly in water or undergo structural changes when suspended in aqueous solutions. However, they often dissolve readily and maintain their structural integrity in solvents such as acetonitrile, methanol or trifluoroacetic acid (TFA). These solvents help create uniform solutions and preserve sample stability during the freezing step of the freeze drying process.
Typical solvent freeze drying applications include:
- Preparative HPLC fractions
- Solvent removal after chromatography
- Organic dyes and pigments
- Polymers in benzol
- Organic substances in solvents
Challenges of freeze drying solvent compounds
- Low freezing points
Solvents such as methanol (–97°C) and acetonitrile (–45.7 °C) require condensers that reach low temperatures to effectively trap vapours in the ice condenser.
- Corrosion to the freeze dryer
Solvents such as methanol (–97°C) and acetonitrile (–45.7 °C) require condensers that reach low temperatures to effectively trap vapours in the ice condenser.
- Safety aspects
Many solvents are flammable or toxic, raising the importance of explosion-proof designs, careful venting and inert gas options.
Why Use Christ Freeze Dryers for Solvent Applications?
Martin Christ Gefriertrocknungsanlagen GmbH is a global leader in laboratory and pilot-scale freeze drying equipment.
Their freeze dryers are known for precision engineering, automation and safety features, making them ideal for demanding solvent drying applications.
Martin Christ offers tailored systems designed to handle low, medium and high solvent concentrations. Each configuration includes the necessary safety and performance features to ensure effective and secure processing of solvent containing samples.
For more information on the different solvent concentration classifications, please refer to the following link: https://www.martinchrist.de/en/applications/solvents/classification
Solutions for low concentrations
The standard laboratory and pilot freeze dryers manufactured by Christ are suitable for low concentration solvents due to the high quality materials used.
Solutions for medium & high concentrations
The pilot freeze dryers (Epsilon 1-4 LSCplus, Epsilon 2-4 LSCplus, Epsilon 2-6 LSCplus and Epsilon 2-10 LSCplus) can be adapted for medium concentration solvents to include chemical resistant valves and door seals, special vacuum pumps and adapted refrigeration systems.
Christ has developed three freeze dryer units capable of handling high concentration solvents: one laboratory scale (Alpha 3-4 LSCbasic and two pilot scale freeze dryers (Epsilon 2-6 LSCplus and Epsilon 2-10 LSCplus). The liquid and gas contacting parts have been carefully considered to ensure a safe and durable freeze drying process. The appearance of the pilot units is characterised by the solvent resistant and robust stainless steel door with glass window. The vacuum is generated by an oil-free scroll pump, which is ATEX explosion-proof certified.
Product spotlight: Alpha 3-4 LSCbasic
The Christ Alpha 3-4 LSCbasic is a laboratory freeze-dryer configured specifically for handling solvent containing samples. This model is ideal for research and analytical applications where volatile, flammable organic solvents are involved.
Key Benefits & Features
Low Temperature Ice Condenser
- Equipped with an internal ice condenser that reaches –105 °C which efficiently captures solvents such as acetonitrile, methanol, DMSO and TFA.
- Ice condenser capacity of 4 kg and sublimation performance of 2.5 kg/24 hours
Solvent-Resistant Construction & Safety Focus
- Built from 316L grade stainless steel with solvent resistant seals, ensuring excellent chemical resistance and stable vacuum performance.
- Equipped with a capacitive vacuum sensor as standard which eliminates the ignition risk associated with Pirani sensors on standard units.
- Features an oil free, ATEX certified vacuum pump (Scroll pump) which is resistant to solvent degradation.
- Provides a connection for inertisation, allowing introduction of nitrogen into the ice condenser chamber via the aeration valve
User Friendly Control Panel
- Controlled via the LSCbasic interface which features a 5.7″ colour touchscreen, intuitive menus, automatic or manual process continuation and password protection.
- Includes graphical system representation, detailed diagnostic messages, maintenance scheduling, and process data capture/export via USB/Ethernet.
- Allows vacuum control functionality which reduces drying times by up to 40%.
Flexible Configurations
- Available in two configurations for versatile lab needs:
- Solvent Package Flask: manifold with 12 chemical-resistant valves for flask-based drying.
- Universal Solvent Package for flask and shelf drying: mineral glass drying chamber with 12 chemical resistant flask valves plus 3 unheated round shelves (Ø 265 mm).
Equipped with natural refrigerants
- Uses environmentally friendly natural refrigerants which have a low GWP (Global Warming Potential) and remains CFC‑free.