Phosphate Buffered Saline (PBS)
Laboratory Supplies
Available sizes: 3 ml, 10 ml
A buffered physiological salt solution
PBS is an aqueous solution of sodium chloride and phosphate salts, formulated to roughly pH 7.4 at an osmolarity and ionic strength approximating extracellular fluid. Potassium salts are included in many formulations.
The phosphate is the functional part. A buffer resists pH change when acid or base is introduced, so a preparation made up in PBS holds its conditions in a way that one made up in plain water does not.
What it is used for
Washing steps in cell culture and immunoassay work, where osmolarity must not shock the cells
Diluting proteins and peptides where a held pH and physiological ionic strength are required
Carrier and vehicle preparation in biological assays
Control conditions, where PBS is the standard vehicle against which a treatment is compared
Choosing it over water
PBS is the right choice when the preparation will meet something that cares about pH or ionic strength — living cells, an enzyme, a binding assay. For simple reconstitution of a lyophilised peptide that is stable at neutral pH and will be diluted further, bacteriostatic water is usually the simpler option and adds no salts to the preparation.
Related supplies
Bacteriostatic Water for general reconstitution, and Acetic Acid Water for peptides requiring acidic conditions.
Documentation and verification
Certificates of Analysis are published for tested products and batches. A certificate is a batch-specific record: it reports what was measured, by which method, on a stated date, against a batch identifier. It is evidence about the sample analysed at the time of analysis, and it is silent on attributes it does not list and on what has happened to the material since.
The batch number is the field that connects the document to a physical vial. Where the identifier on a vial does not appear on a certificate, the certificate does not describe that vial, however thorough the analysis behind it was. Batch records can be searched directly, and the guides below explain what each field establishes and what it does not.
- Verify a batchSearch a batch number for the certificate records published against it.
- How to read a certificate of analysisWhat each field reports, and the limits of what a certificate can establish.
- Certificate, specification and safety data sheetThree documents that answer three different questions.
- Storage and handlingWhat defined storage conditions mean, and why cold slows degradation.
- Batch numbers and traceabilityHow an identifier ties material to the analysis describing it.
Supplied for laboratory research use only. Not for human or veterinary use.