Primary amines tagging

Amines are another important group of analytes. Mellbin and Smith [72] compared three different fluorescent reagents, dansyl chloride, 4-chloro-7-nitrobenzo-1,2,5-oxadiazole, and o-phthaldialdehyde, for derivatization of alkylamines. The dansyl tag was found to be the most effective. Hamachi et al. [73] described the application of an HPLC-POCL method for determination of a fluorescent derivative of the synthetic peptide ebiratide. Another comparative study was done by Kwakman et al. [74], where naphthalene-2,3-dialdehyde and anthracene-2,3-dial-dehyde were evaluated as precolumn labeling agents for primary amines. The anthracene-2,3-dialdehyde derivatives were not stable, especially in the presence of hydrogen peroxide, and the POCL detection of these derivatives was therefore... 

A synthetic acridinium ester, 4-(2-succinimidyloxycarbonylethyl)phenyl-10-methylacridinium-9-carboxylate fluorosulfonate (acridinium NHS) can be used to label unhindered primary amine functionalities (Fig. 6), and using this interface for CL detection, it was later satisfactorily applied for performing trace peptide CE separation with CL detection [81]. In this case, the acridinium labeling of the peptides is done in a precolumn mode, prior to injection. The tagging reaction is run at pH 8, and is determined to reach completion in 15 min by... 

Fisher, R. J. (2003). Quantitative proteomics employing primary amine affinity tags./. Biomol. Tech. 14, 216-223. 

Sample Derivatization. For HPLC analyses, many analytes are chemically derivatized before or after chromatographic separation to increase their ability to be detected. For example, in automated amino acid analyzers, eluted amino acids are reacted with ninhydrin in a postcolumn reactor (see Chapter 20). The resulting chromogenic species are then detected with a photometer. Other examples include labeling amino acids or other primary amines with dansyl or fluorescamine tags either before or after the chromatographic step. 

Ladlow and coworkers have reported the use of fluorous-tagged aldehydes as a protecting group in the synthesis of a library of sulfonamides. The F-aldehyde was prepared via a simple alkylation of 4-hydroxy-2-meoxybanzaldehyde with a perfluo-roalkyl halide. The authors have protected various primary amines with the F-aldehyde followed by reduction, sulfonylation and Suzuki coupling and acid-mediated deprotection. Filtration via a fluorous SPE (solid phase extraction) was... 

Unlike ninhydrin, the reaction of amino acids with OPA does not destroy the amino acids, but adds the fluorescent tag to the primary amine. This allows OPA to also be used as a precolumn derivative, since the derivatization product is unique for each amino acid. 

Berthod et al. also tried copper complexation with teicoplanin and TAG CSPs [19]. Similar results were obtained. Amino acid enantiomers perfectly separated by both teicoplanin and TAG CSP could no longer be separated as soon as copper was present in the mobile phase. The copper-teicoplanin complex is also formed with the primary amine group on the peptidic teicoplanin basket (Figs. 1 and 3). However, unlike the vancomycin-copper complex which was very stable [18], the teicoplanin-copper complex was found to be reversible. Indeed, amino acid enan-tioselectivity was mostly restored after washing the chiral column with several column volumes of copper-free clean mobile phase [19]. 

---