Formaldehyde (3%)

• 1. Prepare monobasic sodium phosphate buffer by dissolving 4.22 g of sodium dihydrogen orthophosphate hydrate (NaH₂PO₄ · H₂O) in 250 mL of ddH₂O. Adjust the pH to ∼7.4.

• 2. In a hood, immediately before use, prepare 3% (v/v) formaldehyde by adding 1.5 mL of 37% (w/v) formaldehyde solution to 48.5 mL of monobasic sodium phosphate buffer.

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