Overview

Sodium Phosphate Buffer, 1 M, pH 7.4 - Sodium Phosphate Buffer provides a pure phosphate buffering system at pH 7.4 without the NaCl and KCl load of PBS. It is intended for users who need to control ionic strength independently while retaining the stability of phosphate buffering near neutral pH.

The formulation uses the audited Henderson-Hasselbalch acid/base ratio for pH 7.4, then final pH verification by meter before filtration and release.

Use and Applications

  • IMAC binding and wash buffers where Tris would interfere with downstream assays
  • Enzyme-activity assays and protein-folding studies near neutral pH
  • Dialysis and chromatography buffers where the user adds NaCl separately
  • General biochemical buffering where temperature stability is more important than Tris compatibility

Specifications

ItemSpecification
Bottle500 mL sterile borosilicate bottle
Concentration1 M total sodium phosphate, pH 7.4
Sterility0.2 um sterile-filtered
DocumentationCoA with pH, conductivity, and lot traceability

Composition

ComponentAmount / concentrationFunction
Na2HPO40.608 M; CAS 7558-79-4Base form of phosphate
NaH2PO4.H2O0.392 M; CAS 10049-21-5Acid form of phosphate
NaOH / HClminor trim onlyFinal pH adjustment
Ultrapure waterq.s. to final volumeASTM Type I solvent

Instruction

1Dissolve the phosphate salts sequentially in approximately 70% of the final water volume.
2Verify pH at 25 deg C and fine-trim with minimal 1 M NaOH or 1 M HCl.
3Bring to final volume, mix thoroughly, and sterile-filter through 0.2 um PES.
4Dilute as required for working buffers; common final concentrations are 10-100 mM phosphate.

Note

  • This product is not PBS. It intentionally contains no NaCl, KCl, CaCl2, or MgCl2.

Cautions

Caution. Phosphate buffers can precipitate divalent metal ions. Avoid use with Ca2+, Mg2+, Mn2+, Zn2+, or Ni2+ when soluble metal availability is critical.
Caution. Do not use phosphate buffer for phosphatase assays unless the assay has been explicitly validated with phosphate present.

Storage and Expiry · Safety

  • Store at room temperature or 2-8 deg C.
  • Unopened shelf life: 24 months from manufacture after QC validation.
  • Transport. Ships at ambient temperature; no cold chain required. Protect from freezing and from temperatures above 40 deg C.
  • Handling and PPE. Wear a laboratory coat, nitrile gloves, and safety glasses for routine handling. The formulated buffer presents no significant hazard under normal use; avoid ingestion and eye contact. Consult the Safety Data Sheet before use.

References

  1. CRC Handbook of Chemistry and Physics, phosphate pKa data.
  2. GMExpression Buffer & pH Indicator Navigator V1.0.

Frequently Asked Questions

Q1. How is this different from PBS?
PBS is an isotonic saline wash buffer. This product is a salt-free 1 M phosphate stock for assays and chromatography.
Q2. Can customers request another pH?
Yes. pH 6.8-8.0 variants are feasible using the same phosphate pair and final meter adjustment.