A method of purifying a defined quantity of nucleic acid, the nucleic acid being present in an in vivo cellular environment, the nucleic acid and in vivo cellular environment being contained in a medium, the method comprising: (a) combining the medium containing nucleic acid with a definable amount of a binding matrix capable of reversibly binding nucleic acid, and a first formulation, the first formulation being sufficient to cause the nucleic acid to separate from its in vivo cellular environment and to bind to the binding matrix, under a first set of binding conditions, wherein the amount of nucleic acid bound to the binding matrix is essentially independent of the amount of surface area of the definable amount of the binding matrix, wherein said binding matrix comprises one or more materials selected from the group consisting of paramagnetic cellulose particles, paramagnetic zeolite particles, paramagnetic silica particles, silica membranes, chemically modified cellulosic materials comprising vicinal diols, zeolite, and nylon; (b) separating the binding matrix with nucleic acid bound thereto from substantially the rest of the combined medium and formulation; (c) eluting the nucleic acid from the binding matrix, thereby obtaining nucleic acid in a substantially purified form; (d) forming a complex of the binding matrix used in step (a) after the elution of the matrix in step (c) and the nucleic acid eluted in step (c) (the amount of nucleic acid being in excess of the binding capacity of the binding matrix), by combining the binding matrix, a second formulation, and the nucleic acid and the medium, under a second set of binding conditions, wherein the amount of nucleic acid bound to the definable amount of binding matrix is essentially dependent on the amount of surface area of the definable amount of the binding matrix; (e) removing the complex formed in step (d) with the nucleic acid bound thereto from the medium, and (f) separating the nucleic acid of step (e) from the complex, whereby a defined quantity of nucleic acid is obtained. (a) combining the medium containing nucleic acid with a definable amount of a binding matrix capable of reversibly binding nucleic acid, and a first formulation, the first formulation being sufficient to cause the nucleic acid to separate from its in vivo cellular environment and to bind to the binding matrix, under a first set of binding conditions, wherein the amount of nucleic acid bound to the binding matrix is essentially independent of the amount of surface area of the definable amount of the binding matrix, wherein said binding matrix comprises one or more materials selected from the group consisting of paramagnetic cellulose particles, paramagnetic zeolite particles, paramagnetic silica particles, silica membranes, chemically modified cellulosic materials comprising vicinal diols, zeolite, and nylon; (b) separating the binding matrix with nucleic acid bound thereto from substantially the rest of the combined medium and formulation; (c) eluting the nucleic acid from the binding matrix, thereby obtaining nucleic acid in a substantially purified form; (d) forming a complex of the binding matrix used in step (a) after the elution of the matrix in step (c) and the nucleic acid eluted in step (c) (the amount of nucleic acid being in excess of the binding capacity of the binding matrix), by combining the binding matrix, a second formulation, and the nucleic acid and the medium, under a second set of binding conditions, wherein the amount of nucleic acid bound to the definable amount of binding matrix is essentially dependent on the amount of surface area of the definable amount of the binding matrix; (e) removing the complex formed in step (d) with the nucleic acid bound thereto from the medium, and (f) separating the nucleic acid of step (e) from the complex, whereby a defined quantity of nucleic acid is obtained.