Dragendorff s reagent

Most of the thiazoles studied absorb in the ultraviolet above 254 nm, and the best detection for these compounds is an ultraviolet lamp (with plates containing a fluorescent indicator). Other indicator systems also exist, among which 5% phosphomolybdic acid in ethanol, diazotized sulfanilic acid or Pauly s reagent (Dragendorff s reagent for arylthiazoles), sulfuric anisaldehyde, and vanillin sulfuric acid followed by Dragendorff s reagent develop alkylthiazoles. Iodine vapor is also a useful wide-spectrum indicator. 

FIGURE 11.4 Video scans of Fumaria officinalis chromatogram developed on alumina layer in eluent systems (a) 10% PrOH + CHjClj (b) first development with 10% PrOH + CH2CI2 on a distance of 18 cm and second development with MeOH on a distance of 10 cm. Plates scaimed after derivatization with Dragendorff s reagent. 

Lycopodium alkaloids Lycopodiaceae sp. SiOj CHClj-MeOH-NHj Dragendorff s reagent Identification 9... 

FIGURE 11.6 (a) Densitogram of PLC of Fumaria officinalis herb extract and (b) photocopy of isolated fractions (after spraying with Dragendorff s reagent). Numbers indicate isolated fractions. System silica/CHjClj + PrOH + AcOH (5 4 1). Plates double developed. 

FIGURE 11.23 Densitograms of Fumaria muralis herb extract chromatographed in system silica/PrOH + MeOH + AcOH + water + CHjClj (28 2 2 2 66). Plates double developed (a) plate scanned at 254 nm (b) plate scanned at 400 nm after spraying with Dragendorff s reagent. 

Figure 11.23a and Figure 11.23b show densitograms from the separation of Fumaria muralis extract scaimed in UV 254 mn (Figure 11.23a) and at 400 nm after spraying with Dragendorff s reagent (Figure 11.23b). It is seen that derivatization enables determination of alkaloid zones and their isolation from the nonalkaloid extract components.

Dragendorff s reagent Dissolve 0.85 g of bismuth subnitrate in a mixture of 40 mL of water and 10 mL of glacial acetic acid (,Solution A). Dissolve 8 g of potassium iodide in 20 mL of water (Solution B). Transfer 5 mL of Solution A, 5 mL of Solution B, and 20 mL of glacial acetic acid to a 100 mL volumetric flask, dilute with water to volume, and mix. 

In the procedure with mobile phase 1 and 2, the visualization is accomplished by screening under uv light (254 and 366 nm) and in addition by spraying with Dragendorff s reagent, modified by Munier and Deboeuf, followed by 30 percent hydrogen peroxide. 

Beside the modified Dragendorff s reagent/hydrogen peroxide already mentioned, a variety of spraying reagents has been used for the visualization of bromocriptine. 

Reagents for detecting hydralazine were Dragendorff s reagent, alkaline dimethylaminobenzaldehyde, anisaldehyde, and Bratton-Marshall reagent. 

There are a number of reasons for this. For example, in many of the solvent systems which are used, compounds are often not completely resolved, as exemplified by the data presented in Table 5.2. Furthermore, neither potassium iodoplatinate or Dragendorff s reagent are specific to opiates. It is therefore necessary to employ a more definitive technique. 

Staining with Dragendorff s reagent and Reifer s reagent revealed alkaloids near the outer surface of green stems of Lupinus luteus. A smaller amount of... 

Vinblastine and vincristine were detected with Dragendorff s reagent, iodine/potassium iodide, and ceruric ammonium sulfate as well as by fluorescence (6). Jaffrey reagent was applied to purified vindoline on chromatograms... 

After purification by Bondapak Cl8 Porasil B column chromatography, hyalbidone was obtained as a yellow oil, which showed a strong positive reaction to Dragendorff s reagent. Neither EI-MS nor FAB-MS gave the molecular ion peak but m/z 222 (for M -30). The H-NMR... 

Application of bis-(2-ethylhexyl) orthophosphate as a liquid ion exchanger in the complete or selective extraction of alkaloids from a buffered aqueous phase has been described. The behaviour of the salts of various alkaloids upon titration with base has been compared.Correlations have been made between the Rf of a number of alkaloids and the pH of an aqueous buffer solution which extracts half of the alkaloid from an aqueous solution. The stabilization of alkaloid solutions has been discussed. " Chromatographic separations of alkaloids by ion-exchange, adsorption, thin-layer, paper, and liquid chromatography have been reviewed. Reference lists have been compiled for methods and applications published in 1970—73 of chromatography and of electrophoresis of alkaloids on paper and thin layers. The optimum composition of Dragendorff s reagent for efficient alkaloid precipitation has been examined. ... 

Dragendorff s reagent + 1 N hydrochloric acid Brown-red precipitate... 

TLC has also been used for quantitative determinations of the tropane alkaloids. Belladonna alkaloids can be determined by quantitative TLC (Samples of Belladonna are extracted according to the method of Pharm. Helv. V (Swiss Pharmacopeia V). The alkaloids so extracted are then separated on kiesel gel G plates with the solvent acetone-aqueous ammonia (19 1). After development, the chromatograms are dried, sprayed with Dragendorff s reagent and the areas of the spots are measured. 

Dragendorff s reagent. The spots are scanned at 490 nm with a recording and integrating densitometer. 

Extraction of alkaloids was effected with warm 0.1 N H2SO4. After filtration, the filterate was adjusted to pH 9-10 with aqueous NH4CI-NH3 buffer. Purification was done through Extrelut column and eluted with CHCla. The concentrated eluate was applied to TLC plates coated with silica gel F2S4 which developed in the solvent system acetone-water-25% ammonia solution (90 7 3). After development, the plates were immersed in Dragendorff s reagent and scanned by densitometry at 520 nm. 

Dragendorff s reagent. Methaqualone forms an orange color most drugs form a brown color. Dissolve 2.2 g of bismuth subnitrate in 25 mL of glacial acetic acid and add 100 mL of water. Dissolve 50g of potassium iodide in 125 mL of water. Combine 10 raL of each of these solutions with 20 mL of glacial acetic acid and 100 mL of water. Store in dark bottle. Reagent will remain stable for 6 months. 

Silica Gel G Ethyl Ac-MeOH-NH OH (170 20 10) Iodoplatinate-Dragendorff s reagent 0.75 17... 

Silica Gel G CHClj-Isopro-T>anol-5%NH OH (74.4 25 0.6) Dragendorff s Reagent l t... 

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