Fluorescence derivatisation

In LIF detection systems, excitation power may be increased up to six orders of magnitude compared to CF detection. Most LC-LIF detection concerns under-ivatised polynuclear aromatic hydrocarbons (PAHs) and fluorescing dyes (e.g. polymethines). Because only a limited number of analytes possess native fluorescence, derivatisation of the analyte before detection is normally required in trace analysis of organic solutes by means of LIF detection. LIF detection in HPLC was reviewed... 

Fig. 2.2.2 a Reaction of tri-n-butylphosphine as a reducing agent, b Reaction of the derivatisa-tion of Hey with ammonium 7-fluorobenzo-2-oxa-l,3-diazole-4-sulfonate (SBDF), which is a fluorescent derivatising reagent... 

Apart from 5 to 8% of all existing molecules that possess natural fluorescence, many others can be made to fluoresce by chemical modification or by association with a fluorescence molecule. By chemical reaction, a fluorophore reagent can be incorporated into the analyte (7-hydroxycoumarines can be used to this effect). This is called fluorescence derivatisation, a process analogous to that used in colorimetry. In HPLC, amines can be fluorescently labelled, permitting very low limits of detection to be achieved — in the order of attomoles (10-18 mol). 

CE separation of fluorescently derivatised microcystins and detection nsing a laser-induced fluorescent detector (Li 1999) however, an evaluation of this method is still required. 

Due to the selective nature of the most sensitive detectors, electrochemical and fluorescence, derivatisation is often required to take advantage of these. Derivatisation has also been used to improve sensitivity of methods using UV detection by adding a more strongly absorbing chromophore. Derivatisation can be combined with trace enrichment a detection level of 70ngr for aldicarb (2-methyl-2-(methylthio) propanol 0-[(methyl-amino)carbonyl] oxime), aldicarb sulphoxide and aldicarb sulphone has been quoted for 10-ml sample volumes using this technique. 

Nohta, H., Sonoda, J., Yoshida, H., Satozono, H., Ishida, J., and Yamaguchi, M., Liquid chromatographic determination of dicarboxylic acids based on intramolecular excimer-forming fluorescence derivatisation, J. Chromatogr. A, 1010, 37-44, 2003. 

In conclusion, the specific detector chosen for the quantitation of the catecholamines is very dependent on the specific apphcation for which the system is to be used. For systems requiring high sensitivity either electrochemical or fluorescence derivatisation systems are probably optimal. If sensitivity is not a problem, then clearly the choice of detector is wider and the selected system could utiUse electrochemical, native fluorescence or even UV detection. 

Lindroth, P. and K. Mopper. 1979. High performance liquid chromatographic determination of subpicomole amounts of amino acids by precolumn fluorescence derivatisation with o-phthaldialdehyde. Anal. Chem. 51 1667-1674. 

Fluorescence derivatisation reagent used in hplc of carboxylic acids. Mp 104°, Mp 139° (dimorph.). 

Fluorescent derivatisation reagent for carboxylic acids used in hplc. Yellow needles (hexane/EtOAc). Mp 161-163°. 

Fluorescence derivatisation reagent for hplc of carboxylic acids and monosialogangliosides. Yellow needles. Mp 170° dec. 

Fluorescent derivatisation reagent for amines. Cryst. (EtOH). Mp 286°. 

Fluorescent derivatisation reagent for alcohols. Pale yellow prismatic needles (CHCl3/pet. ether). Mp 143°. Me ether, fluoride [129601-67-8]. l-Methoxy-l-oxo-lW-l-benzopyran-3-car bony I fluoride. 7-Methoxycoumarin-3-carbonyl fluoride C11H7FO4 M 222.172... 

CisHioNjOS M 266.323 Reagent used for the fluorescence derivatisation of alcohols, amines and thiols. Cryst. (cyclohexane). Mp 142°. 

Fluorescent derivatisation reagent for alcohols and amines. Needles. Mp 176-177.5°. 

Fluorescence derivatisation reagent for primary amines. Plates. Mp 135-136°. 

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