Cryotomy Troubleshooting
Possible sources of error, causes and remedies [1]
| Problem | Cause | Remedy |
|---|---|---|
| Frost on cryochamber walls and microtome. |
• The cryostat is exposed to air currents (open windows, doors, air conditioning). • Sliding window was open too long at a very low cryochamber temperature. • Frost built up by breathing into the cryochamber. |
• Eliminate cause or relocate instrument. • Close the sliding window correctly. Wear a mask if necessary. |
| Ice formation on the bottom of the cryochamber. | • Draining of condensation water of the quick freeze shelf defrosting system obstructed. |
• Level the instrument. |
| Lubricate sections. | • Specimen not cold enough. • Knife and/or anti-roll plate not yet cold enough – the section melts as a result. |
• Select lower temperature. • Wait until knife and/or anti- roll plate have reached cryochamber temperature. |
| Sections splinter, cracks in the section. |
• Specimen too cold. | • Select higher temperature. |
| Sections not properly flattened. | • Static electricity/air currents. • Specimen not cold enough. • Large scale specimen. • Anti-roll plate poorly positioned. • Anti-roll plate poorly aligned with knife edge. • Incorrect clearance angle. • Knife dull or jagged. |
• Eliminate cause. • Select lower temperature. • Trim the specimen parallel; increase section thickness. • Reposition anti-roll plate. • Align correctly. • Set the correct clearance angle. • Use a different part of the knife. |
| Sections not properly flattened despite correct temperature and correctly aligned anti-roll plate. | • Dirt on knife and/or anti-roll plate. • Edge of anti-roll plate damaged. • Dull knife. |
• Clean with dry cloth or brush. • Replace anti-roll plate. • Use a different part of the knife. |
| Sections curl on anti-roll plate. | • Align anti-roll plate correctly. | |
| Scraping noise during sectioning and specimen head return stroke. | • Align anti-roll plate correctly. | |
| Uneven Sections | • Knife damaged • Edge of anti-roll plate damaged. |
• Use a different part of the knife. • Replace anti-roll plate. |
| Chatter during sectioning. | • Specimen insufficiently frozen onto the specimen disc. • Specimen disc not clamped tightly. • Ball-and-socket joint of the holder not clamped into place tightly. • Knife not clamped tightly enough. • Specimen has been sectioned too thickly and has detached from the disc. • Very hard, inhomogeneous specimen. • Dull knife. • Knife profile inappropriate for this specimen used. • Incorrect clearance angle. |
• Refreeze specimen onto the disc. • Check clamping. • Check clamping of the ball-and-socket joint. • Check knife clamping. • Refreeze specimen onto the disc. • Increase section thickness; reduce specimen surface area if necessary. • Use a different part of the knife. • Use knife with different profile. • Use knife with different profile. |
| Condensation on anti-roll plate and knife during cleaning. |
• Brush, forceps, cloth or other cleaning materials too warm. |
• Use only cooled components and cleaning materials. Store all tools on storage shelf in the cryochamber. |
| Anti-roll plate damaged after adjustment. |
• Anti-roll plate too high above the knife edge. The adjustment was carried out in the direction of the knife. |
• Replace anti-roll plate; then lift it during adjustment. • Handle anti-roll plate more carefully! |
- Reproduced from pages 62-63 in Lecia Biosystems Leica CM1520 Cryosta Instructions for Use [14 0491 81101].thttps://www.leicabiosystems.com/sites/default/files/media_product-download/2022-01/Leica_CM1520_IFU_2v4O_en.pdf ↵