FS-7500 Freeze Substitution System

FS-7500 Freeze Substitution System Find Your Local Dealer

Trouble-free freeze-substitution and low temperature embedding on a routine basis.

Safety

• Built-in high capacity exhaust fan with hose automatically vents substitution chamber when cover removed
• Cryo transfer tool provided to safely & conveniently remove cold sample holders
• Large acryllic work surface with anti-spill lip

Convenience

• Internal illumination of substitution work chamber automatically activated when chamber cover removed
• Wide variety of specimen holders, baskets & embedding molds
• Low LN2 coolant consumption
• Programmable data key to store individual substitution protocols
• LN2 Dewar can be refilled during a substitution run
• User friendly digital controller stores up to 10 substitution programs

Results

• N2 gas booster automatically activated when substitution chamber cover removed to minimize O2 contamination
• Performs conventional and PLT substitution
• Reliable & repeatable results with 4 temperature soak and 3 temperature ramp settings
  

Features

• Programmable temperature control for trouble free substitution and low temperature embedding routinely. Performs conventional or PLT (Progressive Lowering of Temperature) substitution automatically.
• Independent temperature control for substitution and polymerization chamber for reliable and reproducible results:
• Substitution chamber temperature from -140C to +70C with +/- 0.1C stability.
• Four holding time settings from 0-999 hours for each.
• Three temperature/time ramp settings.
• User friendly 10 memory programmable process controller for substitution chamber. Programs can be stored on removable "data keys" for safe storage.
• Low LN2 coolant consumption with the ability to refill the 35 liter dewar while a substitution is in progress.
• Several specimen holder varieties available for maximum flexibility.

Description

An essential prerequisite for successful cryo-substitution is starting with good cryo-fixation such as double-sided propane jet freezing, metal mirror freezing or high pressure freezing. Successfully cryofixed samples, typically stored in LN₂ are then transferred into the FS7500 where the substitution solvent is pre-programmed to a temperature below that where secondary ice crystal growth can occur (typically 190K for most biological samples) and above the melting point temperature of the solvent being used.

The FS7500 uses liquid nitrogen as a coolant to achieve a base operating temperature of ?140C (133K) which is well below the ice recrystallization temperature in any biological structure. The temperature of the substitution chamber is set & regulated by the system controller to an accuracy of better than +/- 0.1C over the range from -140C to + 70C

The FS7500 is a free standing, caster wheel mounted, system with a large, hard acrylic, worktop mounted on to its 35 liter high efficiency LN₂ Dewar. The temperature controlled substitution chamber is conveniently located in the center of the worktop for easy access. The chamber is provided with a viewing port/cover, which is simply lifted off to gain access into the substitution workspace. As it is lifted off, the ventilation system is automatically turned on to extract fumes and the chamber internal illumination is turned on.

Low temperature embedding in methacrylates, such as Lowicryl K4M, is commonly employed in freeze substitution and is accommodated in the FS7500 system with appropriate embedding molds and holders. Polymerization of the resin is generally by long wave UV irradiation for several hours at 240K. It is important during this process to minimize the presence of O₂ in the chamber since O₂ is a very strong inhibitor of the polymerization of the resin. This is achieved in the FS7500 by an automatic N₂ gas generator, which is turned on whenever the chamber cover is removed. An ultraviolet lamp, with power supply, is provided as standard with each FS7500 system.

The substitution media is a solvent such as acetone or methanol, which slowly dissolves away and replaces the ice in the frozen specimen. The solvent is placed in commonly used laboratory items such as Eppendorf tubes, scintillation vials, glass cryo-vials, Beem capsules, gelatin capsules, etc, which in turn are placed in the FS7500 specimen holder. A universal specimen holder is provided with the system which accommodates most of these commonly used cryo-vials and containers, and a "start up" kit of these consumables is provided with each FS7500 system.

The specimen holders used with the FS7500 are designed with a large thermal mass to provide good temperature uniformity and stability.

These features combine to make the FS7500 an extremely convenient to use and versatile Freeze Substitution System.