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. 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. Highlights: ? 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