Why Do PCR Tube Caps Burst? The Science Behind the Problem
The fundamental cause is a pressure imbalance inside the tube. During thermal cycling, the sample liquid heats up, increasing vapor pressure. If the tube is improperly sealed, this pressure can force the cap open, much like a lid popping off a boiling pot.
Troubleshooting and Solutions: A Practical Guide
Addressing cap bursting requires a systematic approach to your lab’s consumables and practices. The table below outlines the common causes and their direct solutions.
| Cause | GSBIO’s Solution |
| Incompatible plastics or design | Verify compatibility of the caps and tubes with your thermal cycler model. |
| Improper or insufficient sealing | Ensure caps are tightly in place across the entire rim of the tube/well. Use a cap installing tool to apply consistent, firm pressure. |
| Excessive lid pressure | Adjust the thermal cycler lid to ensure it’s not overtightened. The pressure should be firm enough to seal but not to deform or crush the tubes. |
| Uneven tube distribution | Distribute tubes evenly across the block to balance pressure. If running fewer samples, place empty tubes in the unused wells. |
| Low-quality plastics | Use high-grade, thin-walled virgin polypropylene tubes designed for thermal cycling to withstand rapid temperature changes. |
| Overfilling tubes | Adhere to the recommended fill volumes to allow for adequate headspace and prevent pressure buildup. |
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Post time: Nov-14-2025