Guide to Selecting PCR EP and Strip Tubes for Labs

In molecular biology laboratories, selecting appropriate consumables is crucial for experimental success. While PCR tubes, microcentrifuge tubes (often called Eppendorf or EP tubes), and strip tubes may appear similar at first glance, they serve distinct purposes and are not interchangeable. This article examines the characteristics, applications, and key differences between these essential laboratory tools to help researchers make informed choices.

PCR Tubes: Designed for Polymerase Chain Reaction

PCR tubes are specifically engineered for polymerase chain reaction (PCR), the revolutionary technique for amplifying specific DNA sequences in vitro. These tubes play a critical role in applications ranging from gene cloning and expression analysis to medical diagnostics and forensic science.

Structural Features

• Thin-walled design: Facilitates rapid and uniform heat transfer during thermal cycling, minimizing temperature lag between the reaction mixture and the thermocycler block.
• Material: Typically made from polypropylene (PP) for chemical resistance and thermal stability.
• Cap design: Modern PCR tubes feature flat caps compatible with heated-lid thermal cyclers, while older domed-cap designs accommodated instruments without heated lids.

Primary Applications

• Standard PCR amplification
• Quantitative PCR (qPCR)
• Reverse transcription PCR (RT-PCR)
• Mutation detection and genotyping
• Forensic DNA analysis

Microcentrifuge Tubes: Versatile Workhorses for Sample Processing

Originally popularized by Eppendorf (hence "EP tubes"), microcentrifuge tubes are among the most frequently used laboratory consumables for centrifugation, sample mixing, and storage.

Structural Features

• Thick-walled construction: Withstands high centrifugal forces (up to 20,000 × g).
• Material options: Available in polypropylene (PP) or polyethylene (PE), with PP offering superior chemical resistance.
• Capacity variants: Commonly 0.2 mL, 0.5 mL, 1.5 mL, or 2.0 mL volumes.
• Closure mechanisms: Include snap caps (for easy one-handed operation) and screw caps (for enhanced sealing).

Primary Applications

• Centrifugation of biological samples
• Sample mixing and storage
• Enzymatic reactions (restriction digests, ligations)
• Protein precipitation
• Cell pelleting

Strip Tubes: High-Throughput Solutions

For laboratories processing numerous samples simultaneously, strip tubes (typically 8-tube strips) significantly enhance workflow efficiency while reducing handling errors.

Structural Features

• Integrated design: Eight interconnected tubes minimize individual tube handling.
• Material: Manufactured from chemically resistant polypropylene.
• Cap options: Individual caps per tube or single strip caps for simultaneous opening/closing.
• Automation compatibility: Designed for use with multichannel pipettes and liquid handling systems.

Primary Applications

• High-throughput PCR/qPCR
• Genotyping and SNP analysis
• Next-generation sequencing library preparation
• Compound screening
• Epidemiological studies

Comparative Analysis: Key Differences

Selection Guidelines

When choosing between these consumables, consider:

• PCR applications: Always use dedicated PCR tubes with uniform thin walls for thermal cycling. For qPCR, ensure optical clarity.
• Centrifugation: Select microcentrifuge tubes rated for your required RCF.
• Sample storage: Microcentrifuge tubes with secure seals are preferable.
• High-throughput workflows: Strip tubes dramatically improve efficiency for large sample numbers.

Best Practices for Reliable Results

• Maintain strict contamination control protocols
• Clearly label all tubes with permanent markers
• Adhere to recommended fill volumes
• Ensure proper sealing to prevent evaporation
• Follow standardized handling procedures

Understanding the distinct roles of these fundamental laboratory tools enables researchers to optimize experimental workflows and generate reproducible, high-quality data across diverse molecular biology applications.