Dansylamino acid

Dansylamides 104,106 — 108 Dansylamino acids 73,107,108 Dansylation 72 ff amines (prim, and sec.) 73 amino acids 73 -, phenols 73 prechromatographic 72 ff with dansyl semicadaveride 73, 53... 

The most commonplace substrates in energy-transfer analytical CL methods are aryl oxalates such as to(2,4,6-trichlorophenyl) oxalate (TCPO) and z s(2,4-dinitrophenyl) oxalate (DNPO), which are oxidized with hydrogen peroxide [7, 8], In this process, which is known as the peroxyoxalate-CL (PO-CL) reaction, the fluorophore analyte is a native or derivatized fluorescent organic substance such as a polynuclear aromatic hydrocarbon, dansylamino acid, carboxylic acid, phenothiazine, or catecholamines, for example. The mechanism of the reaction between aryl oxalates and hydrogen peroxide is believed to generate dioxetane-l,2-dione, which may itself decompose to yield an excited-state species. Its interaction with a suitable fluorophore results in energy transfer to the fluorophore, and the subsequent emission can be exploited to develop analytical CL-based determinations. 

Likewise, the luminescence properties of many analytes can be altered in the presenoe of surfactant aggregates (4,7.,8.). Consequently, addition of micelle-forming surfactants (present either in the LC mobile phase or added post-column) can improve the sensitivity of fluorimetric LC detectors (49,482). Micellar spray reagents have been utilized to enhance the fluorescence densitometric detection of dansylamino acids or polycyclic aromatic hydrocarbons (483). The effect was observed for TLC performed on cellulose or polyamide stationary phases with the micellar spray reagent being either CTAC, SB-12, or NaC (483). More recently, use of nonionic Triton X-100 has been found to improve the HPLC detection of morphine by fluorescence determination after post-column derivatization (486) as well as improve the N-chlorination procedure for the detection of amines, amides, and related compounds on thin-layer chromatograms (488). 

Figure 16-la. Dependence of the selectivity on the temperature within chiral separations of DL-dansylamino acids. 

Figure 16-3. Chiral separation of DL-dansylamino acids on an L-proline stationary phase at 25 °C (eluent 75/25 w/w acetonitrile/acetate buffer).

DANS-NH-CH-CO2H + amino acids DANSylamino acid... 

Thin layer chromatography of the dansylamino acid obtained from the hydrolysate together with a series of samples of authentic dansylamino acids and... 

Bhushan and Ali (1987) tested amino acid separations on silica gel layers impregnated with various metal salts. Bhushan and Reddy (1989) reported the separation of phenylthiohydantoin (PTH) amino acids on silica gel with new mobile phases. Laskar and Basak (1988) de.scribed a new ninhydrin-based procedure that produced different colors and good sensitivity for amino acid detection. Bhushan and Reddy (1987) reviewed the TLC of PTH amino acids. Gankina et al. (1989) described a unidimensional multistep silica gel HPTLC method for the separation and identification of PTH and dansylamino acids. Bhushan et al. (1987) developed numerous solvent systems for effective separations of 2,4-dini-trophenyl-(DNP) amino acids. Bhushan (1988) reviewed the TLC resolution of enantiomeric amino acids and their derivatives. Kuhn et al. (1989) reported the amino acid enantiomer separation by TLC on cellulose of d- and L-tryptophan and methyltryptophan. Guenther (1988) determined TLC-separated enantiomers by densitometry. 

Armstrong (142) published a work focusing on the use of the macrocyclic antibiotic vancomycin as a chiral mobile phase additive. In this work the separations of carbamates, derivatized amino acids, racemic drugs and dansylamino acids were performed on diphenyl modified stationary phases with the eluent systems acetonitrile-0.6 M NaCl-1% triethylammonium acetate buffer (pH 4.1). 

Sinibaldi, M., Messina, A. and Girelli, A.M., Separation of dansylamino acid enantiomers by thin-layer chromatography, Ana/jif, 113, 1245-1247,1988. 

Bhushan, R. and Parshad, V., Thin-layer chromatographic separation of enantiomeric dansylamino acids using a macrocyclic antibiotic as a chiral selector, J. Chromatogr. A, 736, 235-238,1996. 

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