The invention provides methods for removing a contaminant or inhibitor from a nucleic acid-comprising sample, wherein the contaminant or inhibitor inhibits the amplification or hybridization of the nucleic acid in the sample, or inhibits an enzymatic reaction utilizing the nucleic acid in the sample, the method comprising the steps of: (a) providing a reaction mixture comprising the sample, a chaotropic agent, ammonium acetate or an equivalent, and a detergent, (b) isolating the nucleic acid and remaining contaminants and inhibitors from the reaction mixture in a supernatant; and (c) contacting the nucleic acid supernantant with a flocculant resulting in the further removal of the contaminant or the inhibitor from the supernatant. The invention also provides kits that comprise the components necessary to carry out the method.