The industry problemThe industry problem
Dimethyl Sulfoxide (DMSO) is the industry standard solublisation agent for small molecule compounds. DMSO has gained this status because of its properties, which include excellent solubilising abilities, low reactivity (it is very inert) and thermodynamic properties such has high freezing and boiling points.

However, despite its wide use, DMSO is not without its problems……

DMSO is an aggressively hydrophilic substance, absorbing moisture rapidly from the surrounding air rapidly. This moisture absorption can result in irreversible damage to precious small molecule compound libraries, which are every Research Operations crown jewels. Moisture related damage can be seen in the following forms:

  • Dilution – DMSO can see in excess of a 20% weight gain in just 24 hours
  • Freezing point depression – DMSO that is 20% saturated with just moisture will not freeze until below -30°C. As a result compound cannot be frozen and reactions will take place allowing compound degradation
  • Precipitation – hydrate formation will cause compound to fall out of solution
  • Crystallisation – moisture will freeze into ice crystals, crushing solubilised compound

In addition to the above, compounds can be damaged by exposure to oxygen (which is highly reactive) and aggressive light conditions (which contain UV).

Moisture is the enemy......

Ultimately the key to compound storage is to avoid exposure to moisture. In recent years providers of automated storage systems have been manufacturing storage systems that maintain compounds within inert (and temperature controlled) environments.

However, these systems are generally large and expensive, making them available to only large Research Operations for their central compound storage efforts.

OK, so how should compounds be stored?

Compounds should ideally be stored in the following conditions:

  • A moisture free environment (to stop moisture absorption)
  • A oxygen free environment (to stop oxygen reactions)
  • A dark environment (to stop UV damage)

Provided the above storage conditions are employed, compounds can be stored for long periods of time and re-accessed on multiple occasions.

Freeze thaw cycles are sometimes considered to be damaging to compounds, with Research Professionals often referring to their compounds falling out of solution as a result. However, this freeze thaw related damage has been traced to the presence of moisture in DMSO.

There has now been substantial research that concludes compounds suspended in moisture free DMSO, can be subjected to multiple freeze thaw cycles without damage.