PCR Tubes

Quick Answer: PCR tubes are small, thin-walled plastic tubes, usually polypropylene, that each hold one polymerase chain reaction in the heated block of a thermal cycler. The common format is a 0.2 ml tube with a hinged cap; the size of this listing should be matched to your cycler.

Why the Walls Are Thin

A PCR cycle swings the reaction between about 95 °C for denaturation, a lower annealing temperature and about 72 °C for extension, often thirty or more times. Thin, uniform walls let the mix follow each temperature change quickly, which is why ordinary microcentrifuge tubes, with thicker walls and a different shape, are not used in a cycler block.

The 0.2 ml size is standard for modern cyclers, while some older instruments were built for 0.5 ml tubes, and the two cannot be swapped in the same block. Single tubes are the most flexible choice for small runs, such as a classroom demonstration with a handful of samples, a pair of positive and negative controls or a quick colony check.

Polypropylene is used because it tolerates repeated heating close to boiling and binds little DNA. For sensitive work, ask whether the tubes carry a nuclease-free statement, and keep the bag closed between uses.

Specifications

Applications

• Student practicals that amplify a gene from their own cheek-cell DNA
• Colony PCR to check a single bacterial clone
• Running controls alongside a strip or plate
• Short incubations such as enzyme digests in a thermal cycler

Care & Handling

• Open and close caps with a clean gloved hand and never touch the inside of the cap.
• Mark the tube side with a fine marker before adding liquids.
• Flick or briefly spin tubes after loading so no droplet clings to the wall.
• Seal used tubes holding amplified DNA in a bag before discarding, to limit amplicon spread.

Why Choose LabEquip

Schools introducing biotechnology practicals and research labs running small checks both rely on single PCR tubes. LabEquip supplies them in its Biology Lab Products range, with a PCR tube rack to hold them during set-up; volume and cap style can be discussed on the contact page.

Frequently Asked Questions

Can I use a 1.5 ml microcentrifuge tube in a thermal cycler?

No. Microcentrifuge tubes do not fit PCR block wells and their thick walls slow heat transfer, so reactions would not reach the programmed temperatures in time. Use PCR tubes of the size your cycler is built for.

What is the difference between 0.2 ml and 0.5 ml PCR tubes?

The 0.2 ml tube is the standard for most current cyclers and heats small volumes faster. The 0.5 ml tube is for older cyclers with larger wells; the two sizes cannot be interchanged in the same block.

How much reaction volume goes into a PCR tube?

Reactions in 0.2 ml tubes are typically 10 to 50 microlitres. Larger volumes heat more slowly and leave little space under the cap, so follow the volume range in your PCR kit’s protocol.

Do PCR tubes need to be sterile?

Freedom from DNA and nucleases matters more than sterility. Tubes taken straight from a closed bag with clean gloves are normally used as they are, and many labs never autoclave them.

Why did my PCR tube lose volume during cycling?

Evaporation happens when the cap is not fully closed or the heated lid is off or not touching the caps. Make sure every cap clicks shut and the lid is properly closed before starting the programme.

Can I write on the cap of a PCR tube?

For end-point PCR, writing on the cap is fine with an ethanol-resistant marker. For qPCR, write on the side instead, because ink on the cap can block the fluorescence signal.

Last Updated: September 2026