the polymerase chain reaction is one of the most widely used techniques in molecular biology . in general , most thermocyclers which automate the pcr nucleic acid amplification process rely upon programmable heat blocks with a large thermal mass . consequently , most of the time in an automated pcr cycle is spent non - productively in transition between denaturation , annealing , and elongation temperatures . recently , much faster hot - air thermocyclers have been constructed which shorten these transition times , allowing 30 cycles of pcr in 10 to 30 minutes . while elegant in principle , the design of these systems is not optimal . air is a relatively poor heat transfer medium ; and the operation of a single heat / reaction chamber at atmospheric pressure is inherently slow . much faster thermocyclers can be constructed using pressurized gas delivered to a thermostated reaction chamber by computer - controlled electronic valves . a novel process , high - speed gas phase pcr , is described . this process has been successfully automated using a novel thermocycing device , which has been successfully to amplify dna from picogram to microgram amounts in ˜ 1 to 5 minutes .