RNA quality is perhaps the most important factor in generating reliable and reproducible Real-Time PCR data. Traditionally, RNA quality was assessed using gel electrophoresis and comparing the 28S and 18S ribosomal RNA bands. Gel electrophoresis is a laborious, time consuming, and low-throughput method that requires fairly large amounts of RNA.
Automated lab-on-chip capillary electrophoresis systems such as the Bioanalyzer (Agilent) and Experion (BioRad) have become popular tools for determining RNA quality. These systems use microfluidic technology to perform electrophoresis on glass chips at a miniaturized scale that overcome some of the issues of traditional electrophoresis. Data are presented as an electrophoretic trace of the RNA sample. The Agilent Bioanalyzer provides a quantitative measure of RNA integrity known as the RNA Integrity Number (RIN). A proprietary software algorithm examines the entire electrophoretic trace to determine RNA degradation and gives a numerical value between 1 and 10 to indicate RNA quality. An RNA sample with a RIN value of 10 is considered a highly intact sample where as a sample with a RIN value of 1 is considered a highly degraded sample.