How to Prepare 1x PBS (Phosphate Buffered Saline, pH 7.4)

1. 1Step 1: Prepare stock solutions - For 1M NaCl: dissolve 5.844g NaCl in 100mL water. For 1M KCl: dissolve 7.455g KCl in 100mL water. For 100mM Na2HPO4: dissolve 1.420g Na2HPO4 in 100mL water. For 100mM KH2PO4: dissolve 1.361g KH2PO4 in 100mL water
2. 2Step 2: In a 100mL volumetric flask, add approximately 80mL of sterile distilled water
3. 3Step 3: Add 13.7mL of 1M NaCl stock solution using a pipette
4. 4Step 4: Add 0.27mL of 1M KCl stock solution using a micropipette
5. 5Step 5: Add 10mL of 100mM Na2HPO4 stock solution using a pipette
6. 6Step 6: Add 1.8mL of 100mM KH2PO4 stock solution using a pipette
7. 7Step 7: Mix gently by inversion several times
8. 8Step 8: Adjust volume to exactly 100mL with sterile distilled water
9. 9Step 9: Mix thoroughly by inversion 10-15 times until homogeneous

PBS naturally buffers to pH 7.4 ± 0.1. No adjustment typically needed. If pH adjustment is required, use small amounts of 1M HCl or 1M NaOH

Autoclave at 121°C, 15 psi for 15 minutes. Allow to cool before use. Alternatively, filter sterilize through 0.22μm filter if heat-sensitive components will be added later

Level 1 safety: Standard laboratory gloves, safety glasses, and lab coat. All components are non-hazardous. Ensure good ventilation when handling powders to avoid inhalation

Store at room temperature in sterile container. Stable for 6 months. Check for cloudiness or precipitate before use - discard if present. Can be stored at 4°C to extend shelf life

Cold Spring Harbor Protocols

Phosphate-Buffered Saline (PBS)