Abstract: A composition for reducing the inhibitory effects of contaminants on nucleic acid amplification is provided. The composition includes a plurality of zirconium oxide particles, a non-ionic surfactant, and an organic iron-chelating reagent. The organic iron-chelating reagent has a first affmity constant greater than or equal to 104.2 with respect to ferric iron and a second affinity constant less than 103.8 with respect to magnesium, wherein the first affmity constant and the second affinity constant are determined in deionized water at pH 8.45 and 20° C. Optionally, the composition includes polyvinylpyrrolidone. Optionally, the composition comprises water. The composition has a pH of about 8.45 to 8.85. Methods of using the composition to prepare a sample for nucleic acid amplification are also provided.