Living in the Microbial World

How to make 10x Phosphate Buffered Saline, pH 7.4

(0.2 M phosphate, 1.5 M NaCl)

• 2.28 g NaH₂PO₄ (mw=120; 0.038M) or 2.62g NaH₂PO₄(H₂O) (mw=137.99; 0.038M)
  (Note: monobasic!!!)
• 11.5g Na₂HPO₄ (mw=141.96; 0.162M)
  (Note: dibasic!!!)
• 43.84g NaCl

• Add NaH₂PO₄ and Na₂HPO₄ and NaCl to 450 ml dH₂O.
• Adjust pH to 7.4 by adding dilute (1N) HCl if necessary.
• Bring the final volume to 500 ml with water.
• Dilute 1:10 for final concentration.

• Cook in regular oven 275F for 1 hour, wrapped in tin foil!