Gel Loading Dye

A Gel Loading Dye is a pre-mixed laboratory solution added to DNA or RNA samples before agarose or polyacrylamide gel electrophoresis.

Key Functions

• Density Agent: Contains a heavy compound like glycerol or Ficoll to make the sample denser than the running buffer, ensuring it sinks cleanly to the bottom of the gel well.
• Tracking Dyes: Contains visual color markers (such as Bromophenol Blue, Xylene Cyanol, or Orange G) that migrate alongside the nucleic acids to track the progress of the run.
• Sample Protection: Often includes EDTA to chelate divalent metal ions and inhibit nuclease activity.

Common Formulations

Concentration: Typically supplied as a 6x or 10x concentrated solution (mixed with the sample at a 1:5 ratio).

Common Dyes:

• Bromophenol Blue: Migrates roughly equivalent to medium-sized DNA fragments (~300 bp in standard gels).
• Orange G: Runs fast with small fragments (~50 bp) and does not obscure UV gel photography.
• Xylene Cyanol: Moves slowly with large fragments (3–5 kb).