Drug Discovery & Screening

Buying guide

Because this work spans dispensing, detection and analysis, the price range across the catalogue is wider than on any one category page. Listings run from EUR 0 to EUR 667.428. The low end is reagents, small molecule stock and consumables, the chemistry a screen burns through rather than the hardware that runs it. The high end belongs to the confirmation side: mass spectrometers and chromatography systems are the costly instruments here, and an automated liquid handler configured for high-density plates sits well up the range too. Microplate readers fall between those extremes, with price tracking the detection modes a unit supports.

Condition shapes what is on offer across all of it. 97 percent of the listings are used. For analytical instruments that figure reflects a long service life, where a well-maintained spectrometer or chromatograph performs to specification years after first sale, and a used unit is listed below a new one. Where the choice between new and used is close, the deciding factor is usually the individual listing rather than the condition label, and warranty is arranged in consultation for the specific unit.

Stock from across 104 countries means the full chain of this work, from the solvent a library is dissolved in to the instrument that confirms a hit, can be assembled from one catalogue. Parts for a given unit can be sourced via Questpair, and where documentation is missing the specialists respond within the hour.

Types of Drug Discovery & Screening

Drug discovery and screening is not a single sequence but a set of linked campaigns, and the equipment this work draws on reflects that: automated liquid handlers and microplate readers for the screen itself, chromatographs and mass spectrometers for the chemistry and the confirmation, PCR and flow cytometry for cell-based readouts, and the compound and reagent stock the assays consume. The work runs in stages, from preparing a library through running the primary screen to confirming what it turns up, and the sections below follow that order.

How is a compound library prepared and dispensed?

Before any assay runs, the library has to reach the assay plate at a known concentration in a known volume. This is where automated liquid handling sits at the centre of the setup: source plates of small molecules in solvent, serial dilution into assay plates, and transfer of nanolitre to microlitre volumes across 96, 384 or 1536 wells. The precision demanded here propagates downstream, because a dispensing error on the source plate becomes a false reading on every well it feeds. The chemicals, fine chemicals and small molecule listings in the catalogue are the stock these steps consume, and the reagent and synthesis category covers what goes into building and formatting a library in the first place. A handler chosen for an early-stage screen and one chosen for confirmation runs face different constraints, because the first prizes throughput and the second prizes carryover control between samples.

Running the primary screen

The primary screen is the throughput step, where thousands of wells are read for a single endpoint. Microplate readers do the measuring: absorbance, fluorescence or luminescence depending on the assay chemistry, read across a full plate in a fixed window so that signal does not drift from the first well to the last. Immunoassay systems carry the binding-based readouts, where a target-ligand interaction is turned into a measurable signal. The step that precedes this, dispensing, and the step that reads it constrain each other directly: a reader optimised for luminescence is wasted on an absorbance assay, and the dispensing format fixes the plate density the reader has to handle. This is the connection a single category page cannot make, because each knows only its own instrument.

What confirms a hit once the screen flags one?

A primary hit is a candidate, not a result. Confirmation leans on the analytical side of the bench. Chromatography separates a mixture so that the active component can be isolated and its purity checked, and mass spectrometers identify what is actually present, confirming the compound's mass and structure against what the library record says it should be. For cell-based work, flow cytometers measure response at the single-cell level and PCR equipment quantifies changes in gene expression that follow a treatment. Pharmaceutical equipment covers the formulation and handling steps that sit around this analytical work. Each of these stages can send a candidate back to the dispensing step for a dose-response run, so the workflow loops rather than ending at a single pass.