A method of preparing a DNA library in a multi-purpose buffer, comprising: a) combining a genomic DNA sample with a multi-purpose buffer, wherein said multi-purpose buffer comprises dNTPs and random primers suitable for use in whole genome amplification; b) contacting said multi-purpose buffer with a plurality of substantially purified enzymes, wherein said enzymes have polymerase activity, kinase activity, and phosphatase activity, wherein said plurality of substantially purified enzymes comprises phi 29 polymerase, Klenow exo-polymerase, polynucleotide kinase, and a pyrophosphatase enzyme, and wherein said contacting is under conditions such that amplified nucleic acid is generated from the genomic DNA sample by whole genome amplification; c) treating said multi-purpose buffer such that sheared amplified nucleic acid is generated from the amplified nucleic acid; d) treating said multi-purpose buffer to inactivate said polymerase activity; and e) contacting said multi-purpose buffer with a ligase and nucleic acid adapters under conditions such that an adapter-linked DNA library is generated from the sheared amplified nucleic acid, wherein said ligase is T4 ligase, wherein said multi-purpose buffer further comprises: (i) a buffering agent, wherein said buffering agent is tris(hydroxymethyl)aminomethane (TRIS); (ii) an emulsifier, wherein said emulsifier is a polysorbate; (iii) a divalent metal cation; (iv) an inorganic salt, wherein said inorganic salt is ammonium sulfate; (v) polyadenylic acid; (vi) an alpha-linked disaccharide, wherein said alpha-linked disaccharide comprises Trehalose; (vii) a reducing agent, wherein said reducing agent comprises dithiothreitol; and (viii) albumin or an albumin-like protein, and wherein all of the above steps are completed in said multi-purpose buffer without nucleic acid purification and in a single container. a) combining a genomic DNA sample with a multi-purpose buffer, wherein said multi-purpose buffer comprises dNTPs and random primers suitable for use in whole genome amplification; b) contacting said multi-purpose buffer with a plurality of substantially purified enzymes, wherein said enzymes have polymerase activity, kinase activity, and phosphatase activity, wherein said plurality of substantially purified enzymes comprises phi 29 polymerase, Klenow exo-polymerase, polynucleotide kinase, and a pyrophosphatase enzyme, and wherein said contacting is under conditions such that amplified nucleic acid is generated from the genomic DNA sample by whole genome amplification; c) treating said multi-purpose buffer such that sheared amplified nucleic acid is generated from the amplified nucleic acid; d) treating said multi-purpose buffer to inactivate said polymerase activity; and e) contacting said multi-purpose buffer with a ligase and nucleic acid adapters under conditions such that an adapter-linked DNA library is generated from the sheared amplified nucleic acid, wherein said ligase is T4 ligase, wherein said multi-purpose buffer further comprises: (i) a buffering agent, wherein said buffering agent is tris(hydroxymethyl)aminomethane (TRIS); (ii) an emulsifier, wherein said emulsifier is a polysorbate; (iii) a divalent metal cation; (iv) an inorganic salt, wherein said inorganic salt is ammonium sulfate; (v) polyadenylic acid; (vi) an alpha-linked disaccharide, wherein said alpha-linked disaccharide comprises Trehalose; (vii) a reducing agent, wherein said reducing agent comprises dithiothreitol; and (viii) albumin or an albumin-like protein, (i) a buffering agent, wherein said buffering agent is tris(hydroxymethyl)aminomethane (TRIS); (ii) an emulsifier, wherein said emulsifier is a polysorbate; (iii) a divalent metal cation; (iv) an inorganic salt, wherein said inorganic salt is ammonium sulfate; (v) polyadenylic acid; (vi) an alpha-linked disaccharide, wherein said alpha-linked disaccharide comprises Trehalose; (vii) a reducing agent, wherein said reducing agent comprises dithiothreitol; and (viii) albumin or an albumin-like protein,