SM buffer

Recipe

Reagent	Amount	Final concentration
NaCl	5.8 g	100 mM
MgSO₄•7H₂O	2 g	8 mM
Tris-Cl (1 M, pH 7.5)	50 ml	50 mM
H₂O	to 1 liter
To prepare 1 liter of SM buffer, dissolve the NaCl and MgSO₄•7H₂O in 800 ml of H₂O; add the Tris-Cl; and adjust the volume to 1 liter with H₂O. Sterilize the buffer by autoclaving for 20 minutes at 15 psi (1.05 kg/cm²) on liquid cycle. After the solution has cooled, dispense 50-ml aliquots into sterile containers. SM buffer may be stored indefinitely at room temperature. Discard each aliquot after use to minimize the chance of contamination. SM buffer may also be prepared with 0.002% (w/v) gelatin; see the recipe forSM buffer with gelatin.