Sodium phosphate

1 M sodium phosphate buffer (pH 6.0–7.2)

Mixing 1 M NaH₂PO₄ (monobasic) and 1 M Na₂HPO₄ (dibasic) stock solutions in the volumes designated in the table below results in 1 L of 1 M sodium phosphate buffer of the desired pH. To prepare the stock solutions, dissolve 138 g of NaH₂PO₄•H₂O (monobasic; m.w. = 138) in sufficient H₂O to make a final volume of 1 L and dissolve 142 g of Na₂HPO₄ (dibasic; m.w. = 142) in sufficient H₂O to make a final volume of 1 L.

0.1 M sodium phosphate buffer (pH 7.4)

Add 3.1 g of NaH₂PO₄•H₂O and 10.9 g of Na₂HPO₄ (anhydrous) to distilled H₂O to make a volume of 1 L. The pH of the final solution will be 7.4. This buffer can be stored for up to 1 mo at 4°C.

0.1 M sodium phosphate buffer (from 1 M stocks) at 25°C

To prepare 1 L of 0.1 M sodium phosphate buffer of the desired pH, the following mixtures should be diluted to 1 L (final volume) with H₂O.

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