Drugs fluorescent deriv with

This type of derivatization seems promising for the detection of drugs and metabolites with phenolic groups. A recent application on the determination of chlorophenols in surface water showed that the dansyl derivatives of phenols are readily convertible to the highly fluorescent dansyl-OH and dansyl-OCHs products after postchromatographic irradiation (281). Fluorescence gain factors of up to 8000-fold were obtained for chlorophenol derivatives with a low native fluorescence. 

In contrast to the above Deveaux method, Mehta and Schulman [37] described that the native fluorescence of mefenamic, flufenamic and meclofenamic acids is more useful for determination of these drugs compared to the fluorescence of the derivatives-substituted acridones and benzoxazines of these drugs by treatment with H2S04 and HCHO, respectively. The determination of mefenamic acid at trace level by fluorescence spectrometry was also reported by Miller et al. [38]. 

It may also be necessary, especially in biological applications, for the CDA to increase the detectability of the analyte. Some CDAs have, in fact, been designed with sensitive detection in mind, for example, to produce electron-capturing derivatives for GLC or fluorescent derivatives for LC. Sensitive and selective detection is of utmost importance in applications in drug metabolism and pharmacokinetics, where drugs present at low concentrations in complex biological fluids are to be identified and quantified. 

Goto et al. (67) synthesized the sucdnimidyl ester [14] of (—)- -methoxy-a-methyl-l-naphthaleneacetic acid for the normal-phase LC resolution of chiral amines. The reagent permitted the determination of the enantiomers of an amphetamine derivative in blood plasma after administration of racemic drug to rabbits. With detection at 280 nm, the lower limit of sensitivity was 5 ng/mL for each enantiomer (67). Several chiral acids from the "profen" group of nonsteroidal antiinflammatory drugs have been adapted as CDAs. One of these, naproxen, [15], is the S enantiomer and is commercially available as the resolved acid several of these acids have the advantage of providing fluorescent derivatives (68,69). 

Except for a number of aromatic estrogens, the majority of steroids are nonfluorescent. Many steroids react with concentrated sulfuric and phosphoric acid to form fluorescent derivatives, but the lack of selectivity and the formation of a large number of uncharacterized products limit the application of this method in drug testing. 

Further interesting example of NSAIDs, whose fluorescence properties within CD are determined by the mode of inclusion, are nabumetone (10), a naphthalene derivative with a butanone side chain and naproxen (11), a parent propionic acid derivative (Fig. 2). The dominant features of the inclusion of nabumetone inside P-CD are the formation of two conformations of the drug, but the folded structure is the main one, probably due to the presence of water in the proximity of the hydroxyl groups at the gates of CD [59]. This situation... 

A more comprehensive approach was reported in 1975 by Brabander and Verbeke (612). In this method, tissue samples were extracted with methanol and the acidified extract defatted with petroleum ether to be loaded onto a Dowex 50W-X8 anion-exchange resin. Following elution with aqueous methanol, the concentrated buffered extract was further defatted with diethyl ether. The sample was derivatized with 7-chloro-4-nitrobenzo-2-oxa-l,3-diazole (NBD-Cl) to be further spotted on a silica high-performance thin-layer chromatographic plate developed in two dimensions using chloroform/ethanol and chloroform/propionic acid consecutively as eluents. Detection of the propylthiouracil, phenylthiouracil, and tapazole residues was carried out on the basis of the fluorescence induction of the NBD derivatives of the drugs with an alkaline cysteine solution. 

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