Agarose Gel Containing 2.2 m Formaldehyde
To prepare 100 mL of a 1.5% agarose gel containing 2.2 m formaldehyde, add 1.5 g of agarose to 72 mL of sterile H2O. Dissolve the agarose by boiling in a microwave oven. Cool the solution to 55°C, and add 10 mL of 10× MOPS electrophoresis buffer <R> and 18 mL of deionized formaldehyde. In a chemical fume hood, cast an agarose gel with slots formed by a 3-mm comb with at least four more teeth than the number of RNA samples under test. These extra lanes are used for RNA size markers and running dyes. Allow the gel to set for at least 1 h at room temperature. As soon as the agarose has set, cover the gel with clear plastic wrap until the samples are ready to be loaded.
