Please select from the following list:

• 0.1 M NaCl
• 0.2 M NaCl
• 0.1 M Potassium Phosphate, pH 6.5
• 0.1 M Potassium Phosphate, pH 6.5, + 0.65 M NaCl
• Tris/EDTA, 20 mM, pH 8.0
• Tris-Acetate/EDTA, 40 mM, pH 8.0
• Tris/EDTA, 20 mM, pH 8.0 + 0.1 M NaCl