Real-Time PCR

Real-time PCR is a laboratory method that amplifies a target DNA or RNA sequence and measures the product as it accumulates each cycle, using a fluorescent signal. It reports the starting amount of template rather than only confirming its presence.

The term refers to detecting PCR product in real time, as amplification happens, rather than reading a result only at the end. It is also called quantitative PCR or qPCR because it measures template copy number.

A thermal block cycles the reaction through denaturation, annealing and extension while optics read a fluorescent signal that rises as product accumulates. The cycle at which the signal crosses a threshold indicates how much template was present at the start.

The listings here fall into several types: a real-time PCR system (block and optics together), a thermal cycler (the amplification engine alone, sometimes endpoint only), a quantitative PCR instrument, a fluorescence detection system, a multiplex PCR system, and molecular diagnostics equipment configured for clinical testing. Confirm whether a thermal cycler is real-time capable before buying, since some are endpoint only.

It quantifies gene expression, underpins molecular diagnostics such as pathogen detection and oncology panels, and handles genotyping. In genomics and proteomics pipelines qPCR validates sequencing or cell culture results, and in biomanufacturing it confirms the absence of contaminants and the identity of a cell line.

Start with optical channel count, which sets how many dyes and targets you can read in one run, then block format, which follows from throughput. Match both to the assays actually on the bench rather than to ones that might arrive, so you do not pay for channels or wells you will not use.

A used instrument is sold in its existing condition, while a refurbished one has been checked and brought back to working order before listing. Both appear on Questpair below new prices, and the specifics of what was done to a refurbished unit sit in the individual listing.

Prices range from EUR 58 to EUR 172.178, with the average near EUR 7.809. The spread tracks channel count, block format and detection optics, so a single-channel cycler and a high-channel diagnostics platform sit at opposite ends.

The instruments here cluster around Applied Biosystems, Bio-Rad, Roche, Agilent and Thermo Fisher Scientific. Their presence means consumables, replacement lamps and detector parts are easier to find for the common models, and a configuration can be compared against another of the same family.

A warranty is often possible and is arranged in consultation for the specific listing. Terms depend on the individual unit rather than a central policy, so check the listing you are considering.

Parts can be sourced via Questpair. Availability is generally better for the common models from Applied Biosystems, Bio-Rad, Roche, Agilent and Thermo Fisher Scientific, where consumables, lamps and detector components are more widely stocked.

Lifespan depends mostly on the thermal block and the optics, which degrade with cycle count. A Peltier block that has logged heavy use shows up as poor well-to-well uniformity before it fails outright, so a uniformity check tells you more than the hours logged.

Used and refurbished units are listed at lower prices than new, which is often what makes a higher channel count affordable. Where you have to weigh the two, compare the individual listing and remember that warranty is arranged in consultation rather than assumed.

The Questpair catalogue lists 660 real-time PCR systems from 16 verified suppliers and distributors across 10 countries. New, used and refurbished instruments appear side by side.

Lead time and shipping depend on the individual listing and the supplier handling it. For a specific timeline, contact Questpair through the listing and specialists respond within an hour.

The excitation source and detector drift over time and calibration dyes expire, so ask when the instrument was last calibrated and whether a passive reference and dye calibration can be run on arrival. Well-to-well uniformity across the block should also be verified, since poor uniformity corrupts quantification. Questpair does not carry out servicing itself, but parts can be sourced through it.

Complete real-time PCR systems and quantitative PCR instruments suit labs doing gene expression and diagnostics, while a standalone thermal cycler is for amplification where another instrument handles detection. A multiplex PCR system serves genotyping and panels that read several targets at once, and molecular diagnostics equipment is configured for clinical work with its attendant regulatory and software requirements.

Listings concentrate around Applied Biosystems, Bio-Rad, Roche, Agilent and Thermo Fisher Scientific. For a buyer this concentration means parts, consumables and comparable models are easier to find, and cross-platform assay transfer is better documented, which lowers the risk of moving a validated protocol onto a used unit.

The low end covers basic single-channel units and parts, which read one dye and answer presence or quantity for a single target. The high end covers high-channel diagnostics-grade systems with automation and 384-well blocks that read several dyes and raise sample count per run, which is why the gap between EUR 58 and EUR 172.178 is so wide.