For best results, all RNA samples should be suspended in RNase-free water. Alternatively, RNase-free 1 mM sodium citrate (pH 6.5) or 10 mM Tris buffer (pH 7.0) may be used. Do not use DEPC-treated water, as most DEPC preparations are contaminated with molecules that are inhibitory to reverse transcription and/or PCR. For long-term storage, RNA preps may be stored at -70 ºC in RNase-free water
, or the buffers listed above, or precipitated in ethanol or isopropanol. In order to avoid repeated freeze-thaw cycles, it is recommended that frozen RNA samples be stored as multiple, single-use aliquots.