RNA loading buffer is used as a tracking dye during RNA electrophoresis. The dye has a slight negative charge and will migrate the same direction as RNA, allowing the user to monitor the progress of molecules moving through the gel. The rate of migration varies with gel composition. Dilute 1:3 to 1:6 with sample, heat to 65C for ten minutes and chill on ice before loading.
RNA sample loading buffer is especially formulated for electrophoresis of RNA on formaldehyde-agarose gels with or without ethidium bromide. Ethidium bromide is not recommended for gel staining prior to Northern blot detection because the presence of ethidium bromide in agarose gels or the loading buffer can cause poor transfer efficiency.
Suitable for use with formaldehyde-agarose gels used in Northern blotting procedures.
Deionized formamide 62.5% (v/v), formaldehyde 1.14 M, bromphenol blue 200 μg/mL, xylene cyanole 200 μg/mL, MOPS-EDTA-sodium acetate at 1.25× working concentration.
RNA loading buffer contains 62.5% deionized formamide, 1.14M formaldehyde, 200 μg/ml bromphenol blue, 200 μg/ml xylene cyanole, in MOPS-EDTA-sodium acetate at 1.25x working concentration.
Recommended usage: Add 1 volume sample to 2-5 volumes of sample loading buffer and mix well. The sample should be heated to 65 °C for 10 minutes, and then chilled on ice immediately before loading on the gel.