A method of continuously and randomly testing at least one biological sample having an initial concentration of a nucleic acid by PCR testing, the method comprising: selecting randomly the biological sample having an initial NA concentration of a nucleic acid; dispensing the biological sample in a sample tube of a circular vortex and incubation device, said device including a plurality of positions to hold sample tubes; adding an enzyme for degrading the protein structure of the NA; incubating the sample and agitating it via rotation of the circular vortex and incubation device; isolating and purifying the NA by magnetically capturing the NA contained in the biological sample, using magnetic silica particles; removing the sample tube from the vortex and incubation device and disposing it on a sample tube conveyor; washing the NA-carrying magnetic silica particles while the sample tube is on the conveyor; eluting the magnetically-captured NA, using an aqueous elution buffer, to re-suspend the magnetically-captured NA in the aqueous elution buffer to form a purified NA in solution; transferring the eluted sample to another incubation and agitation ring and separating the NA from the magnetic silica particles; adding a pre-determined reagent mixture to the purified NA in solution to provide a reaction liquid; performing a continuous random access polymerase chain reaction testing on the reaction liquid through multiple PCR cycles consisting of denaturing, annealing, and elongating thermal cycles, wherein the PCR testing is performed continuously in a multi-vessel thermal cycler array which is structured and arranged to randomly receive tubes containing the reaction liquid, wherein the multi-vessel thermal cycler comprises a plurality of single-vessel thermal cyclers which are each individually thermally controllable so that adjacent single vessel thermal cyclers can be heated or cooled to different temperatures corresponding to the different thermal cycles of the respective PCR testing process; and estimating the initial NA concentration of the biological sample. selecting randomly the biological sample having an initial NA concentration of a nucleic acid; dispensing the biological sample in a sample tube of a circular vortex and incubation device, said device including a plurality of positions to hold sample tubes; adding an enzyme for degrading the protein structure of the NA; incubating the sample and agitating it via rotation of the circular vortex and incubation device; isolating and purifying the NA by magnetically capturing the NA contained in the biological sample, using magnetic silica particles; removing the sample tube from the vortex and incubation device and disposing it on a sample tube conveyor; washing the NA-carrying magnetic silica particles while the sample tube is on the conveyor; eluting the magnetically-captured NA, using an aqueous elution buffer, to re-suspend the magnetically-captured NA in the aqueous elution buffer to form a purified NA in solution; transferring the eluted sample to another incubation and agitation ring and separating the NA from the magnetic silica particles; adding a pre-determined reagent mixture to the purified NA in solution to provide a reaction liquid; performing a continuous random access polymerase chain reaction testing on the reaction liquid through multiple PCR cycles consisting of denaturing, annealing, and elongating thermal cycles, wherein the PCR testing is performed continuously in a multi-vessel thermal cycler array which is structured and arranged to randomly receive tubes containing the reaction liquid, wherein the multi-vessel thermal cycler comprises a plurality of single-vessel thermal cyclers which are each individually thermally controllable so that adjacent single vessel thermal cyclers can be heated or cooled to different temperatures corresponding to the different thermal cycles of the respective PCR testing process; and estimating the initial NA concentration of the biological sample.