Alkaloids dansylation

Cyclodextrins as chemically banded layers [102] or mobile phase additives [103-105] have been used successfully to resolve a wide variety of alkaloids, steroids and dansyl- and naphthylamide-amino acid derivatives. The low solubility in aqueous solution and f high cost of cyclodextrins restricted the use of these additives > initially. These limitations were overcome by the availability of ... 

Recently the continuous-addition-of-reagent (CAR) technique [182] was applied for the determination of fluorophores by POCL chemistry [95-99], The applicability of this technique was demonstrated by the determination of natively fluorescent acepromazine in horse plasma [95], the alkaloid harmaline in plasma [96], and other dansylated alkaloids [97], A separation step has also been included and applied to postcolumn detection of PAHs [98] and dansylated P-carboline alkaloids [99],... 

Table 4 illustrates the use of the CAR technique to develop CL kinetic-based determinations for various analytes in different fields. As can be seen, the dynamic range, limit of detection, precision, and throughput (—80-100 samples/ h) are all quite good. All determinations are based on the use of the TCPO/ hydrogen peroxide system by exception, that for p-carboline alkaloids uses TCPO and DNPO. A comparison of the analytical figures of merit for these alkaloids reveals that DNPO results in better sensitivity and lower detection limits. However, it also leads to poorer precision as a result of its extremely fast reactions with the analytes. Finally, psychotropic indole derivatives with a chemical structure derived from tryptamines have also been determined, at very low concentrations, by CAR-CLS albeit following derivatization with dansyl chloride. 

Carboxylic acids, dansyl derivates of amino acids Aminopropyl derivate of the ergot alkaloid (+ )-terguride Methanol—acetate, 205 pH range 3.8—5.5... 

The approach of CMPAs has also been used in thin-layer chromatography (TLC) for the chiral resolution of a variety of racemic compounds [100-110]. Lepri et al. [104,105] used BSA as a mobile phase additive for the chiral resolution of dansyl amino acids and other drugs by TLC. Armstrong et al. [101,102] used unde-rivatized and hydroxyethyl and hydroxypropyl /I-cyclodextrins for the chiral resolution of dansyl amino acids, alkaloids, and other compounds. Aboul-Enein... 

Analytical Properties (i-Cyclodextrin (cycloheptamylose) normal phase separation of positional isomers of substituted benzoic acids reverse phase separation of dansyl and napthyl amino acids, several aromatic drugs, steroids, alkaloids, metallocenes, binapthyl crown ethers, aromatics acids, aromatic amines, and aromatic sulfoxides this substrate has seven glucose units and has a relative molecular mass of 1135 the inside cavity has a diameter of 0.78 nm, and the substrate has a water solubility of 1.85 g/ml, although this can be increased by derivatization Reference 13-28... 

Fluorescence detection is highly specific and often extremely sensitive.However, its use is limited to fluorescent alkaloids - eventually to alkaloids made fluorescent by derivati-zation. Various chemical reactions can be used for this purpose, such as oxidation to give fluorescent oxidation products, coupling with fluorescent groups, i.e. dansyl groups, and ion-pairing with fluorescent ions, i.e. picrate, B-naphtalenesulfonate, 9,10-dimethoxyanthra-... 

Fig. 7.15. Analysis of alkaloids in cough syrup after derivatization with dansyl-chloride2 Column Lichrosorb SilOO 10 wm (250x2.8 mm ID), mobile phase diisopropyl ether - isopropanol -cone, ammonia (48 2 0.3), detection UV 254 nm. Peaks 1, Dns-ephedrine 2, noscapine 3, Dns--cephaeline 4, Dns-emetine 5, codeine t, dodecylbenzene. Fluorescence detection witn excitation 360 nm and emission 500-510 nm.

Miscellaneous alkaloid separations Dansyl derivatives of cephaeline, emetine, ephedrine and morphine obtained by direct deriva-tization of syrups and aqueous slurries of capsules having a complex excipient and drug composition Adsorption Silica gel Di-isopropyl ether/isopropanol/ cone, ammonia (48 2 0.3)... 

Substances that lead to the adjustment of pH values. In general, acidified carriers are very useful for the separation of acids and phenols (217), aromatic compounds (218), and dansyl amino acids (219). Sorbents with alkaline pH values can be used particularly for amines, amino acids, and alkaloids (220-222). 

Lepri et al. (114-117) investigated the chromatographic behavior of dansyl-, dinitrophenyl and P-naphthyl-substituted amino acids, and alkaloids on layers of partially CIS-modified silica with aqueous-organic solutions containing P-cyclodextrin as chiral agent. Also the influence of the concentration of urea in the eluent was studied. 

Unfortunately, the hydrolysis product, dansylic acid is strongly fluorescent and can cause interferences with water-soluble derivatives. These derivatives, however, are often removed by the subsequent chromatographic process. The detection limits of the dansyl derivatives are often in the low nanogram range (ca. 1 x 10" g/ml) and the excitation and emission maxima can vary between 350-370 nm excitation and 490-540 nra emission. Some examples of the application of this reagent are in the analysis of amino acids (13), alkaloids (14), barbiturates (15) and pesticides (16). 

Fluorescence detectors are based on filter-fluorimeters or spectrofluori-meters. They are more selective and can be up to three orders of magnitude more sensitive than UV absorbance detectors. The detector responds selectively to naturally fluorescing solutes such as polynuclear aromatics, quinolines, steroids and alkaloids, and to fluorescing derivatives of amines, amino acids and phenols with fluorogenic reagents such as dansyl chloride (5-(dimethylamino)-l-naphthalene sulfonic acid). 

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