Because high affinity nucleic acid binding dyes can affect DNA migration during electrophoresis, post-staining of gels with SYBR and GelRed dyes is highly recommended. Post-electrophoresis staining results in superior sensitivity and eliminates the possibility of dye interference with DNA migration.
While agarose gels can be precast with these dyes, the migration and/or resolution of some DNA ladders may be affected. Therefore, some DNA ladders may require optimization/diution when run on gels precast with these dyes. For optimum results, please follow the dye manufacturer’s recommendations and protocols carefully, specifically concerning the loading amounts.
We recommend using our 1 kb Plus DNA Ladder for Safe Stains (NEB #N0559) when using SYBR or GelRed as precast dyes, as this DNA ladder was specifically optimized for this application.
Additionally, avoid using loading dyes that contain SDS, as SDS might cause an abnormal band pattern in precast gels. We recommend using Gel Loading Dye, Purple (6X), no SDS (NEB #B7025) for this application.”