Compound QC

As compound libraries grow the need to be confident about the quality of the stored samples becomes ever more important. With automated screening systems the scientist often has no opportunity to check the compounds as they are used for the creation of assay plates. The first they know about a problem is unexpected screening results.
Often chemical compound libraries are solubilised in DMSO and then frozen to -20°C or lower. This in itself can cause a variety of issues due to DMSO’s aggressive hydrophilic characteristics including:

•    Precipitation – the solubility decreases as water content increases and often increases with freeze / thaw cycles. Compounds are more likely to fall out of solution due to hydrate formation.
•    Crystallisation – again repeated freeze / thaw cycles generating slow cooling effects can increase the likelihood of crystallisation of amorphous material in the low temperature making re-solubilisation much harder.
•    Depression of freezing point – The DMSO will freeze at much lower temperatures once it is saturated with compounds (e.g. 10% will reduce freezing point from 18°C to <4°C). As a result degradation can occur due to the possibility of unintentional reactions.
•    Concentration – reducing concentration levels to 2-5mM from the more usual 10-30mM can reduce precipitation but this limits the test concentrations used in assays particularly those that cannot tolerate high concentrations of DMSO in the assay buffer (e.g. some cell and enzyme based assays).
•    Decomposition - compounds can degrade due to effects of temperature, light (e.g. UV in organic compounds), pressure and age.

Refrigeration systems can also cause problems themselves such as sublimation of the sample through porous seals or bungs in the tubes in a dry atmosphere. Knowing the quality and state of the stored compounds is therefore of vital importance. With the Lab2Lab system your compound collection can be sent to HPLC or GCMS and analysed overnight without affecting the normal running of the compound library. Problematic compounds can then be discovered and withdrawn from use. Levels of confidence can be gained from returned analytical data and estimated lifetimes could be assigned to compounds.

The Lab2Lab system will seamlessly integrate directly with the TTPLabTech comPOUND system using the additional transport ports available in the comPOUND. Other compound storage system can easily be integrated or the system can be used in a semi-automatic mode where racks of tubes are sent fed to the Bulk Senders.