Ampicillin stock solution (100 mg/mL)
Ampicillin (sodium salt [sodium ampicillin], m.w. = 371.40)
Dissolve 1 g of sodium ampicillin in sufficient H2O to make a final volume of 10 mL. If sterilization is required, prewash a 0.45- or 0.22-μm sterile filter by drawing through 50-100 mL of H2O. Then pass the ampicillin solution through the washed filter. Store the ampicillin in aliquots at -20°C for 1 yr (or at 4°C for 3 mo).
