Capillary electrophoresis

Capillary electrophoresis is a separation technique that moves charged molecules through a narrow fluid-filled capillary under high voltage, separating them by size and charge as they travel toward a detector. It is used across genomics, protein analysis and molecular diagnostics where resolution and automation matter.

The name describes the format: electrophoresis, the migration of charged species in an electric field, carried out inside a thin capillary rather than across a slab gel. The capillary dissipates heat better and allows higher voltages, which gives sharper separations.

A sample is injected into a capillary filled with buffer or a sieving polymer, a high voltage is applied across the capillary, and molecules migrate at rates set by their size and charge. A detector near the far end records each species as it passes, producing an electropherogram with a peak for each separated component.

The listed types include complete capillary electrophoresis systems, DNA fragment analysers, dedicated fragment analysers, DNA sequencers, molecular diagnostics equipment and capillary electrophoresis DNA analysers. The practical split is between instruments that size DNA fragments, those that read base order, and general systems that separate proteins and charged small molecules.

It is used for DNA fragment sizing, Sanger sequencing, microsatellite and STR analysis, clinical genotyping, pathogen identification and protein quality control. The common application is any separation where sharp, reproducible resolution of charged molecules is needed.

Start with the application, because a fragment analyser and a sequencer share the same physics but carry different optics, capillary arrays and software and rarely substitute for each other. Then match the capillary count per run to your real sample load, since a single-capillary bench unit and a multi-capillary array serve very different throughputs.

A used unit is sold in its current working state, while a refurbished unit has been inspected and reconditioned before sale. On both, check the capillary array run count, whether the instrument completes a self-test, and whether recent electropherograms show clean peaks; read the individual listing for what each includes.

Prices in the Questpair catalogue range from EUR 35 to EUR 60.262, with an average near EUR 15.164. A single capillary or spare part sits at the low end, while a fully configured multi-capillary genetic analyser with its workstation sits at the top.

The listings come mainly from Agilent, Applied Biosystems, Beckman Coulter, ProteinSimple and Qiagen. Applied Biosystems and Beckman Coulter built much of the genetic analysis installed base, Agilent covers fragment and protein platforms, ProteinSimple focuses on protein work, and Qiagen reaches into molecular diagnostics.

A warranty is often possible and is arranged in consultation for the specific listing. Check the listing details and confirm the terms before purchase.

Parts can be sourced via Questpair. For the common genetic analysis platforms, consumables such as capillary arrays and polymer circulate more widely, which is one reason a well-represented model is easier to keep running.

The chassis and optics can serve for many years, but the capillary array, pump block and optical alignment are the wearing parts to watch. An instrument whose polymer chemistry or consumables are discontinued is limited regardless of its mechanical condition, so consumable availability often decides usable lifespan.

Used and refurbished systems are listed at lower prices than new, which is what brings a multi-capillary platform within reach of a smaller lab. Weigh the price difference against the condition and inclusions in the individual listing, and note that warranty is arranged in consultation rather than set centrally.

The Questpair catalogue lists these instruments from 12 verified suppliers and distributors across 6 countries, with 136 live listings. You can compare configurations and inclusions across those listings in one place.

Lead time and shipping depend on the individual seller and the instrument's size and configuration, since a multi-capillary system with its workstation ships differently from a single part. The listing is the source for availability, and Questpair specialists respond within one hour to questions about a specific unit.

A sequencer or fragment analyser needs spatial and spectral calibration, and a unit that cannot show a passing calibration is an unknown however good the chassis looks. Routine maintenance centres on replacing the capillary array, maintaining the pump block and polymer, and keeping the optics aligned.

The listed range covers complete systems, DNA fragment analysers, dedicated fragment analysers, DNA sequencers, molecular diagnostics equipment and DNA analysers. A genomics or molecular biology lab reaches for a fragment analyser when the question is size, a lab confirming variants reaches for a sequencer, and clinical labs use molecular diagnostics instruments for validated genotyping and pathogen work.

Agilent, Applied Biosystems and Beckman Coulter account for a large part of the listings. A concentrated field means models are well documented and easy to compare, consumables and spares for the common platforms circulate more widely, and a given model number maps to a known specification.

Price tracks the capillary count, the vintage of the detector, and whether the lot includes the computer and software licence. The low end holds accessories, spares and single capillaries, while the top holds complete multi-capillary genetic analysers with their workstations.