of preheated te buffer for samples prepared from larger i e full thickness tissues the elution process is repeated two additional times after the rna is eluted rna concentration is quantified using a ribogreen assay rna quality is assessed via gel electrophoresis ribogreen reagent nanodrop technologies wilmington del is provided as a stock solution in dmso prior to use the reagent is diluted 2000 fold in te buffer the rna assay requires 200 ml of diluted ribogreen reagent per sample to be tested and 1 ml of reagent as a standard once prepared the diluted reagent is stored protected from light a series of rna standards are prepared by diluting purified ribosomal rna derived from e coli to the following concentrations 2 mg ml 1 mg ml 200 ng ml 40 ng ml and 0 ng ml blank prior to assaying the rna samples prepared above are diluted 1000 fold in te buffer for the rna assay 100 ml of the diluted samples or standards are transferred to the wells of a black 96 well plate the samples and standards are assayed in duplicate after the samples standards are added to the plate 100 ml of diluted ribogreen assay reagent is added to the wells and the plate is gently mixed and allowed to incubate for 5 10 minutes protected from the light.