Why are samples centrifuged at 4°C after addition of chloroform to the QIAzol lysates in following kits: RNeasy Lipid Tissue Mini/Midi kits, RNeasy Microarray Tissue Mini kit, RNeasy Plus Universal Mini/Midi kit, RNeasy 96 Universal Tissue kit, miRNeasy Mini kit, miRNeasy Micro kit, miRNeasy 96 kit and miRNeasy Serum/Plasma kit?

Phase separation by centrifugation at 4°C, after adding chloroform and gDNA Elimiator solution to the samples, minimizes genomic DNA contamination. Subsequent centrifugation steps with RNeasy spin columns have to be carried out at room temperature to prevent buffer salt precipitation and to guarantee optimal binding of RNA to the columns.  This then ensures the highest RNA yields possible.