After doing a PCR, the resulting DNA should be cleaned up to get rid of the primers, the enzymes and the various other reagents used in the PCR.

We used Macherey-Nagel's "Nucleospin&registered; Gel and PCR clean-up" kit. Its manual can be found here: http://www.mn-net.com/Portals/8/attachments/Redakteure_Bio/Protocols/DNA clean-up/UM_PCRcleanup_Gelex_NSGelPCR.pdf