Vacuum Distillation

distillation performed under reduced pressure. Since a reduction in pressure also reduces the boiling point of substances it means that certain substances which at normal pressures would decompose (break down), can be distilled.

Taken from Dictionary of Science

____________________________________________________________

Vacuum distillation is a method of distillation whereby the pressure above the liquid mixture to be distilled is reduced to less than its vapor pressure (usually less than atmospheric pressure) causing evaporation of the most volatile liquid(s) (those with the lowest boiling points). This distillation method works on the principle that boiling occurs when the vapor pressure of a liquid exceeds the ambient pressure. Vacuum distillation is used with or without heating the solution.

Taken from Wikipedia

Labile

a term used in chemistry which means not stable, likely to change.

Taken from Dictionary of Science

___________________________________________________________

The term is used to describe a relatively unstable and transient chemical species. As a general example, if molecule exists in a particular conformation for a short life-time, before adopting a lower energy conformation, the former molecular structure is said to have 'high lability' (such as C₂₅, a 25-carbon fullerene spheroid). The term is sometimes also used in reference to reactivity - for example, a complex which quickly reaches equilibrium in solution is said to be labile (with respect to that solution).

Taken from Wikipedia

Labelled Compound

a compound used in radioactive tracing, where an atom of the compound is replaced by a radioactive ISOTOPE, which can be followed through a biological or physical system by means of the RADIATION it emits.

Taken from Dictionary of Science
_________________________________________

Chemical compound in which a radioactive isotope is substituted for a stable one. The path taken by such a compound through a system can be followed, for example by measuring the radiation emitted.

This powerful and sensitive technique is used in medicine, chemistry, biochemistry, and industry.

Taken from Tiscali