Magnesium ions, added in the form of magnesium chloride (MgCl2), are an essential cofactor for polymerase enzyme activity during PCR. Too low a concentration will result in weak amplification or complete PCR failure, while too much can promote non-specific amplification. Although PCR Master Mixes contain enough MgCl2 for typical use, they may require an increased concentration in some circumstances, for example when compensating for PCR inhibitors present in DNA extracts that might bind to Mg2+ ions.
MgCl2 solution is used for adjusting Mg2+ concentration in PCR reactions. It can be used in combination with Master Mixes such as FIREPol® and HOT FIREPol® Master Mixes, or other commercial Master Mixes, PCR beads and polymerases. In most applications a final concentration of 1.5 mM MgCl2 is optimal for a satisfactory yield.