Chromatography media

A chromatography medium is the stationary-phase material, whether packed in a column or supplied as bulk resin, that a sample passes through so its components separate by how strongly each interacts with the phase. The medium, not the instrument, determines the resolution of a separation.

The term covers the solid or packed materials that provide the stationary phase in a chromatographic separation, including packed analytical columns, preparative columns and loose ion exchange resins. It is distinct from the mobile phase, the solvent or gas that carries the sample through.

A liquid or gas carries the sample through the medium, and each component is retained for a different length of time depending on its affinity for the stationary phase. Components that interact weakly elute first and those that interact strongly elute later, which is what produces the separation.

The listed types include HPLC columns, general chromatography columns, reversed-phase columns, preparative columns, cation exchange resins and broader ion exchange resins. Reversed-phase columns retain analytes by hydrophobic interaction, ion exchange resins separate by charge, and preparative columns are built for throughput rather than measurement.

These media perform protein purification, peptide separation for proteomics ahead of mass spectrometry, and sample cleanup in molecular biology. Ion exchange resins are used in downstream bioprocessing to capture and polish monoclonal antibodies and other biologics, and chromatography also supports quality control of cell culture media and feedstocks.

Settle the separation chemistry first, because it fixes nearly everything downstream: a reversed-phase C18 column and a cation exchange resin separate on different principles and are not interchangeable. Once the mechanism is set, the column dimensions, particle size and pore size follow from the analytes and the pressure the pump can hold.

A used item is sold in its current condition, while a refurbished one has been reconditioned before listing, and both are priced below the new equivalent. For a column either way, the injection history and storage matter more than the label, because the stationary phase degrades with every run.

Prices in the catalogue range from EUR 9 to EUR 12.875, with an average of EUR 668. That spread reflects format rather than condition, since a single analytical cartridge sits far below a bulk preparative column or a sizeable resin quantity.

The names that recur in the listings are Agilent, Phenomenex, Acros Organics, Supelco and Thermo Scientific. A column from an established maker carries a published specification sheet, so a used listing can be matched against a known phase chemistry and particle grade rather than trusted on its printed label.

A warranty is often possible and is arranged in consultation for the specific listing. Because terms depend on the individual seller, check the listing itself for what applies.

Replacement frits, end fittings and guard cartridges are more readily sourced for widely listed brands, and these parts can be sourced via Questpair. Named brands with documented specifications make it easier to identify the correct matching component.

Lifespan depends on use rather than age: a C18 phase loses carbon load and retention over time, frits clog, and void volume opens at the inlet with each injection. An ion exchange resin accumulates fouling and loses binding capacity, so a column's injection count tells you more than its calendar age.

Used and refurbished media are listed below the price of new equivalents, which keeps the entry cost of a trial column low. For a used column, ask for the injection count, the last samples it ran and whether it was stored wet, since history matters more than the specification printed on the hardware.

The Questpair catalogue holds 177 listings from 9 verified suppliers and distributors across 7 countries. New, used and refurbished items are listed together, spanning packed columns and bulk resins.

Lead time and shipping depend on the individual seller and the format of the item, since a single analytical cartridge ships differently from a bulk preparative column or a large resin lot. For a specific listing, Questpair specialists respond within one hour to questions about availability.

Media are not calibrated like an instrument, but their performance is tracked through system suitability runs that check retention, peak shape and resolution. Maintenance centres on storage: keep columns in a compatible solvent, avoid letting the phase dry out, and use guard cartridges to protect the main bed from sample fouling.

The catalogue is led by HPLC columns and general chromatography columns, followed by reversed-phase columns, preparative columns, and cation and ion exchange resins. Analysts developing small-molecule methods reach for reversed-phase C18 columns, bioprocessing teams reach for ion exchange resins to capture biologics, and groups isolating material rather than measuring it choose preparative columns.

Agilent, Phenomenex, Acros Organics, Supelco and Thermo Scientific recur across the listings. For a buyer, a named brand ties a column to a documented phase chemistry and particle grade, or a resin to a defined bead size and functional group, which is what lets a used lot be matched against a published method rather than guessed from the product name.

The gap is driven by format rather than quality: analytical HPLC columns and small resin quantities occupy the lower end, while preparative columns and larger packed beds reach the top. Across the catalogue prices run from EUR 9 to EUR 12.875 with an average of EUR 668, and that spread reflects the difference between a single analytical cartridge and a bulk preparative unit.