PAGE/Urea Solution (19:1 Acrylamide/Bis + 6 M Urea) (6%) - FAQs

There are many sample buffer formulations used, however we have found a distinct difference in the band appearance depending on the sample buffer composition. After evaluating urea, formamide, and various buffer systems, we found that the sharpest, flattest bands were obtained with a urea, Ficoll, and TBE buffer solution. Sample buffers made with formamide resulted in fuzzy, indistinct bands.

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(1) Ethidium bromide: Soak gel in a 2 µg/mL solution of ethidium bromide in ultrapure water for 20 min. Destain by rinsing with three successive 10-min rinses of ultrapure water. Visualize bands under UV light. The gel must be removed from the cassette prior to visualization of the DNA under a UV light. Because polyacrylamide quenches the fluorescence of ethidium bromide, it is not possible to detect bands that contain less than about 10 ng of DNA by this method. SilverXpress and SYBR stains will provide greater detection sensitivity.

(2) Invitrogen SilverXpress Stain: Follow the standard procedure from the instruction booklet for staining TBE or TBE-Urea gels.

(3) SYBR Green I/II Nucleic Acid Gel Stain: See the SYBR Green Staining Manual for protocol details.

Find additional tips, troubleshooting help, and resources within our Nucleic Acid Purification and Analysis Support Center.