Simultaneous isolation and quantitation of DNA

A method of isolating a defined quantity of a DNA target material from other materials in a medium comprising the steps of:

• a. providing a medium containing the DNA target material;
• b. providing a discrete quantity of porous silica magnetic particles with the capacity to reversibly bind a definable quantity of the DNA target material per milligram of particle, the particles having an average particle diameter of about 5.0 to 8.5 microns, a nitrogen BET surface area of about 18 to 55 microns gm and an acid leach resistance of less than about 7 ppm Fe2O3, the amount of DNA target material provided in step (a) being in excess of the binding capacity of the particles;
• c. forming a mixture comprising the medium, the silica magnetic particles, and a chaotropic salt, wherein the chaotropic salt concentration in the mixture is sufficient to cause the DNA target material to adhere to the particles;
• d. incubating the mixture until at least some of the DNA target material is adhered to the silica magnetic particles;
• e. removing the silica magnetic particles and the adhered DNA target material from the mixture using an external magnetic force;
• and
• f. eluting the DNA target material of step (e) from the silica magnetic particles by exposing the particles to an elution solution, whereby a defined quantity of the DNA target material is obtained.

A method of determining a calibration model for quantitating a DNA target material in a sample type of interest, the method comprising:

• a. providing a first medium, wherein the first medium includes a first quantity of the sample type of interest;
• b. providing a second medium, wherein the second medium includes a second quantity of the sample type of interest, wherein the second quantity is greater than the first quantity of the sample type of interest;
• c. mixing a first discrete quantity of silica magnetic particles with the first medium, wherein the silica magnetic particles are capable of reversibly binding a first defined quantity of the DNA target material, thereby forming a first complex of the silica magnetic particles and the DNA target material from the first medium, the discrete quantity of the sample type of interest in the first medium containing DNA target material in excess of the binding capacity of the particles mixed with the first medium;
• d. mixing a second discrete quantity of silica magnetic particles with the second medium, wherein the silica magnetic particles are capable of reversibly binding a second defined quantity of the DNA target material, thereby forming a second complex of the silica magnetic particles and the DNA target material from the second medium, the discrete quantity of the sample type of interest in the second medium containing DNA target material in excess of the binding capacity of the particles mixed with the second medium;
• e. removing the first complex from the first medium and the second complex from the second medium by application of an external magnetic field;
• f. separately eluting the DNA target material from the first complex and second complex, producing a first eluent of isolated DNA target material from the first complex and a second eluent of isolated DNA target material from the second complex;
• g. determining the amount of DNA target material in the first and in the second eluent;
• and
• h. repeating steps a-g with at least one additional discrete quantity of silica magnetic particles until the amount of DNA target material isolated from two different media is determined to be about the same, thereby identifying conditions wherein the DNA binding capacity of the silica magnetic particles is exceeded.

A method of isolating DNA target material from a solid support, the method comprising:

• contacting the solid support containing the DNA target material with a chaotropic salt solution at a temperature of about 60° C. to about 100° C. thereby isolating at least a portion of the DNA target material from the solid support;
• isolating a defined quantity of DNA target material by adding a discrete quantity of silica magnetic particles to the isolated DNA target material to form a complex, the amount of DNA target material isolated from the solid support being in excess of the binding capacity of the particles;
• removing the complex with the DNA target material from the solution by application of an external magnetic field;
• and separating the DNA target material from the complex by eluting the DNA target material, whereby a defined quantity of the DNA target material is obtained.