Thermo Scientific™

TNBSA Solution (2,4,6-trinitrobenzene sulfonic acid) (5% w/v)

Catalog number:  28997

 Related applications:

Protein Assays and Analysis

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Thermo Scientific Pierce TNBSA Solution is a 5% solution of trinitrobenzene sulfonic acid in methanol that reacts with primary amines (peptides or amino acids) to yield a soluble colored product, a property useful for various assay methods.

Features of Thermo Scientific Pierce TNBSA Solution:

• TNBSA component reacts readily with primary amino groups of amino acids in aqueous format at pH 8 to form yellow adducts
• Colored derivatives are monitored at 345nm and have extinction coefficients of 10,000 to 15,000
• Supplied as 5% solution (w/v) of TNBSA in methanol, which is easily diluted approximately 1000-fold in assay buffer for typical protein and peptide applications
• No colored derivatives are formed with secondary amino acids proline and hydroxyproline
• Applicable to solution or solid phase analysis

Properties of TNBSA:
• Alternative names: 2,4,6-trinitrobenzenesulfonic acid (TNBSA), picrylsulfonic acid, trinitrophenylsulfonic acid, trinitrobenzene sulfonate (TNBS)
• Chemical name: 2,4,6-trinitrobenzenesulfonic acid
• Reactive toward: Primary amines (—NH2)
• Chemical formula: C6H3N3O9S
• CAS number: 2508-19-2; 5400-70-4; 85600-65-3
• Molecular weight: 293.17

Example procedure for measuring protein primary amines (Hermanson, 2008, p. 127-128):
• Dissolve or dialyze protein (20-200 µg/mL) in 0.1M sodium bicarbonate buffer (pH 8.5). Avoid Tris or other amine-containing buffers.
• Dilute supplied 5% TNBSA solution 500-fold in 0.1M sodium bicarbonate buffer (pH 8.5).
• Add 0.5 mL diluted TNBSA solution to 1 mL of protein solution. Mix well.
• Incubate at 37°C for 2 hours.
• Add 0.5 mL of 10% SDS and 0.25 mL of 1N HCl to each sample to stop and stabilize reaction.
• Measure absorbance of solution at 335nm. Determine concentration of primary amines by calculation from the extinction coefficient or by comparison to amino acid standards.

This Pierce Reagent solution contains trinitrobenzene sulfonic acid (TNBSA), which reacts readily with the primary amino groups of amino acids in aqueous solution at pH 8 to form yellow adducts. No colored derivatives are formed with the secondary amino acids praline and hydroxyproline. The colored derivatives are monitored at 335 to 345nm and have extinction coefficients in the range of 10,000-15,000. TNBSA has been used as a hydrophilic modifying reagent for the detection of primary amines in samples containing amino acids, peptides or proteins. It is an excellent reagent for rapid qualitative and quantitative estimation of these biomolecules.
For Research Use Only. Not for use in diagnostic procedures.


Chemical Reactivity: Amine
Product Size: 100 mL

Contents & storage

Storage: Upon receipt store at -20°C. Product is shipped at ambient temperature.


Manuals & protocols