Nucleic acid quality is of great importance for microarray analysis. DNA and RNA should have an A 260 to A 280 ratio ∼1.8 and >1.9, respectively and an A 260 to A 320 ≥ 1.7. The A 260 to A 320 ratio is most important in determining microarray success (Ning et al., 2009) . Some environmental samples, especially those with high humics, can be difficult to purify up to the necessary level. A gel purification strategy followed by a phenol-chloroform-butanol extraction (Xie et al., 2007; Liang et al., 2011) has been successful with a wide range of soil and sediment samples.