Dansyl chloride DNS

Dansyl chloride Dns-Cl Primary and secondary amines, phenols, euaino acids and imidazoles 550, 617-619... 

Dansyl chloride (DNS-Cl) (l-dimethylaminonaphthalene-5-sulphonyl-chloride). This reagent was originally introduced into protein chemistry for end-group analysis over twenty years ago (Gray and Hartley, 1963) and has been widely used because of the simplicity of the reaction and its ability to react with both primary and secondary amines, unlike OPA and fluram. Furthermore, in contrast to other fluorescent reagents, the dansyl derivatives are stable to acid hydrolysis, and can therefore be used in N-group labelling before hydrolysis. HPLC separations of dansyl derivatives have recently been published (Tapuhi et al., 1981). Sensitivity of detection is at the low picomole level. The sensitivity is limited because of the side-reactions which can occur with lysine and, to a lesser extent, histidine and tyrosine. 

Dansyl chloride (DNS-Cl 5-dimethylaminonaphtha-lene-l-sulfonyl chloride) is used in analytical chemistry to fluorescently label substances. This process of dansyla-tion creates fluorescent derivatives, which can be detected with great sensitivity. The method for the dansylation of hydroxyl (-OH) and carboxylic acid (-COOH) functional groups has been described. Fluorescent labeling by dansyl chloride has applications in LC, HPLC, TLC, and MS. Fast TLC was accomplished using acetone as the resolving solvent, and resulted in good differentiation of analytes. 

An excellent and detailed discussion of pre-column and post column derivatization has been given by Lawrence (11) and includes a comprehensive list of available reagents, procedures and application examples. One of the more popular procedures is fluorescence derivatization and probably the most popular fluorescent reagent is dansyl chloride (12). 5-Dimethylamino-naphthalene-l-sulphonyl chloride (dansyl chloride, DNS-chloride or DNS-Cl) reacts with phenols and primary and secondary amines under slightly basic conditions to form a fluorescent sulphonate ester or sulphonamide. The quantum efficiency of dansyl derivatives is high whereas the reagent itself does not fluoresce. 

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