Isoprenoid quinones are free lipids that can be readily extracted from bacterial cells using lipid solvents such as
acetone, chloroform and hexane. It is normally achieved with any one of these solvents or with a mixture of any
two of them. They are also susceptible to photo-oxidation in the presence of oxygen and strong light but it is not
necessary to work in a nitrogen atmosphere or dim light. It is, however, good practice to conduct extraction and
subsequent purification procedures fairly rapidly, only storage should be carried out under protected conditions.
It is now well established that isoprenoid quinones occur in the cytoplasmic membranes of most prokaryotes.
Different bacteria not only synthesized different quinone classes (e.g. menaquinones, ubiquinones) but the
number of isoprene units in the multiprenyl side-chain often vary amongst taxa and that this structural variation
can be of value in prokaryote systematics.