The RNeasy UCP Micro Kit is designed for purification of up to 45 μg RNA from small or low biomass samples. The spin columns and buffers are treated to remove exogenous nucleic acids. RNeasy UCP Micro technology combines the selective binding properties of an ultra-clean, silica-based membrane with the speed of microspin technology. Ultra-clean guanidine-thiocyanate–containing lysis buffer RULT and ethanol are added to the sample to create conditions that promote selective binding of RNA to the RNeasy UCP MinElute membrane. The sample is then applied to the RNeasy UCP MinElute spin column and RNA binds to the silica membrane. Traces of DNA that may copurify are removed by DNase treatment on the RNeasy UCP MinElute spin column. DNase and any contaminants are washed away with ultra-clean wash buffers RUWT and RUPE, and high-quality total RNA is eluted in ultra-clean water (see figure RNeasy UCP Micro Kit Procedure). With the RNeasy UCP Micro procedure, all RNA molecules longer than 200 nucleotides are purified. The procedure enriches for mRNA, since most RNAs <200 nucleotides are selectively excluded. Tissue samples can be conveniently stabilized using RNAprotect Tissue Reagent or Allprotect Tissue Reagent, and efficiently disrupted using a TissueRuptor or TissueLyser system.