Gel Loading Dye, Purple (6X) is the premier gel loading dye from NEB for sharp, tight bands. It is a pre-mixed loading buffer which contains a combination of two dyes, Dye 1 (pink/red) and Dye 2 (blue). The red dye serves as the tracking dye for both agarose and non-denaturing polyacrylamide gel electrophoresis. This solution contains SDS, which often results in sharper bands, as some restriction enzymes are known to remain bound to DNA following cleavage. EDTA is also included to chelate magnesium (up to 10 mM) in enzymatic reactions, thereby stopping the reaction. The dye also contains Ficoll, which creates brighter and tighter bands when compared to glycerol loading dyes. Attention SYBR Safe and GelRed dye users: Due to an increased concentration of SDS in B7024S, NEB recommends using Gel Loading Dye, Purple, No SDS (6X) (NEB# B7025S) instead.