Choose a screening library around the biological question, assay conditions and follow-up plan. Compare chemical diversity and practical availability alongside physicochemical properties. A large compound count is useful context, but it does not establish assay suitability or hit quality.
Define the experiment before choosing the compounds
Start with a short selection brief: target or phenotype, assay format, solvent system, intended concentration range, acceptable compound classes and the amount required for follow-up. A biochemical assay and a cellular assay can impose different practical constraints. Your shortlist should reflect the experiment you can run and interpret.
Decide whether the aim is broad exploration, a focused motif search or analogue expansion around a known structure. For broad exploration, review how much scaffold diversity you gain. For analogue work, keep the features you want to test clear and compare changes systematically.
Use property filters as selection tools
Molecular weight, calculated lipophilicity and polar surface area can help shape a manageable shortlist. They are not measurements of solubility, permeability or potency. Choose ranges appropriate to your research question rather than treating one familiar cut-off as universal.
Review structures after filtering. The same numerical range can contain very different ring systems, charges and functional groups. HTS catalogue categories can overlap, and catalogue entries should not be read as a count of distinct scaffolds or unique structures.
Sources: Lovering, Bikker and Humblet: Escape from Flatland (2009)
Plan how you will assess apparent hits
An assay signal can reflect compound behaviour other than the desired interaction. Consider suitable controls and follow-up methods for your assay, including checks for interference and other non-specific effects. Structural alerts can identify questions worth investigating; they do not replace experimental assessment.
Ask which documentation and samples can be supplied for the compounds you shortlist. The HTS site describes structures and catalogue information, not a dataset of validated biological activities. Do not infer assay performance from an attractive scaffold, a category label or a computed descriptor.
Sources: Baell and Holloway: screening-library interference filters (2010)
Before you request a quotation
HTS lists 62,590 in-stock catalogue entries and 395,999 virtual catalogue entries for synthesis enquiries. Stock is supplied as dry powders in labelled individual vials. The physical stock is held in Hamburg; final quantities and documentation are discussed individually.
- Provide compound IDs, required amounts and the number of individual samples.
- State any requirements for chemical form, stereochemistry and purity documentation.
- Clarify the sample format and storage or shipping constraints relevant to your work.
- Ask about stock confirmation, samples and quantities available for follow-up.
- For a larger selection, request a volume quotation and specify how flexible your selection is.
Common questions
Is the largest library always the best screening library?
No. The useful set depends on the assay, chemical diversity, quality information, available amounts and the plan for confirming and following up hits.
Can I obtain a tailored selection instead of the full catalogue?
Yes. Use the search filters to prepare a shortlist, then discuss selected compounds, larger quantities and suitable package terms by email.
Sources & further reading
YOUR NEXT STEP
Find chemistry to evaluate.
Explore the catalogue or send your IDs, quantities and specifications for a tailored quotation.
Catalogue information is distinct from experimental activity data. Counts refer to entries; categories can overlap. Availability, documentation and synthesis feasibility are confirmed individually. Questions or corrections? Email the team.