Gel loading solution is used as a tracking dye during electrophoresis. The dyes have a slight negative charge and will migrate the same direction as DNA, allowing the user to monitor the progress of molecules moving through the gel. The rate of migration varies with gel composition. Dilute 1:6 with sample before loading.

Suitable for use with agarose or non-denaturing polyacrylamide gel electrophoresis (PAGE), which may be part of Northern and Southern blot hybridization procedures.

Gel loading buffer contains 0.25% bromophenol blue, 0.25% xylene cyanol, and 40% sucrose.

Band migration can be expected as follows:
On polyacrylamide gels, xylene cyanole comigrates with approximately 450-460 bp DNA, while bromophenol blue comigrates with 15-100 bp DNA. On 0.5 – 1.4% agarose gels, xylene cyanole comigrates with 4 kb dsDNA, while bromophenol blue comigrates with 300 bp dsDNA.