Alkaloids quantitative determination

Note Under the conditions employed emetine and cephaeline were not well separated but there was good resolution of the subsidiary alkaloids of the ipecacuanha tincture (Fig. 1). The separation and quantitative determination of the main alkaloids (Fig. 2) can be carried out under the following conditions Ascending, one-dimensional development in a trough chamber with chamber saturation layer HPTLC plates Silica gel 60 (Merck) mobile phase dichloromethane — methanol — ammonia solution (25%) (34+6+1) migration distance 6 cm running time 13 min h/ f cephaeline 65-70 emetine 75-80. 

Methylated phenols very often form part of the molecule of natural products, in particular, of alkaloids. In the elucidation of their constitution the quantitative determination of the methoxyl groups is of great importance. This determination is carried out by the excellent method of Zeisel, in which the methyl group is removed as methyl iodide by the action of concentrated hydriodic acid. This method (directions, p. 80) should be practised with the anisole already prepared. 

Schnitzius, J. M., Hill, N. S., Thompson, C. S. and Craig, A. M. 2001. Semi-quantitative determination of ergot alkaloids in seed, straw, and digested samples using a competitive enzyme-linked immunosorbent assay. Journal of Veterinary Diagnostic Investigation, 13 230-237. 

HPLC has found considerable application within the pharmaceutical laboratory. For example, Roos [248] described a HPLC method for the separation, identification and quantitative determination of barbiturates in pharmaceutical dosage forms. The separation of 16 barbiturates was described and the effects of varying experimental parameters discussed. The successful separation of two cinchona alkaloids, four opium alkaloids, and heroin-related narcotics with measurements at nanogram to microgram levels has been achieved [249]. Quantitation and identification of morphine in opium in three samples was described by Wittwer [250]. 

A new method for the quantitative determination of the conformational equilibrium of bisquinolizidine alkaloids in solution, by H and NMR, was developed by Wysocka and Brukwicki [199]. Using sparteine and 5,6-dehydromultiflorine. Fig. (30), as model compounds for a C ring in boat and chair conformation, respectively, the authors showed that the percentage of conformers with the C ring in boat conformation can be determined on the basis of the experimental chemical shifts of C-12 and C-14 and of the J coupling value of H-7/H-17P, by the formula Fb = (5-6c) /(6b-6c), where 5 is the experimentel value, and 5b and 5c represent the 5 or J coupling values of the model compoimds in boat and chair conformation, respectively. 

Micropropagation of ipecac through shoot-tip culture is described in the section 1.1. However it is important to investigate the characteristics of growth and alkaloid content of the regenerated plants that are cultivated in the field to evaluate the tissue culture method. In this section, field-cultivation trial of the regenerated plants in two districts in Japan is described [25]. Alkaloids were quantitatively determined by the HPLC method in section 1.2. 

The alkaloids collected at cathode were washed, dried and their melting points were determined for identification. Additional of NaCl to the electrolyzed solution hastened the separation of alkaloids. Some alkaloids were quantitatively determined (68). 

A photometric method for the quantitative determination of tropane alkaloids has been described (81). 

The application of IR spectrophotometry to the quantitative determinations of tropine alkaloids has been reported (101). The pressed KBr pellet technique was applied in these determinations. Recoveries from standard... 

Paper chromatography has been used for quantitative determinations of the tropane alkaloids or for their separation from crude drugs prior to determination. ... 

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. 

Owing to the low volatility and thermal instability of many alkaloids, derivatization is performed to give them better gas chromatographic properties. Derivatization is, however, also done to give alkaloids better detection properties and for quantitative determinations. 

In a number of investigations the methyl phenyl silicone OV-17 has successfully been used for separation and also for quantitative determinations of tropane alkaloids in pharmaceutical preparations9 10 11 12 13 14 15. 

Other stationary phases have also proved to be useful for gas chromatography o tropane alkaloids. For simultaneous quantitative determination of atropine and scopolamine, Solomon et al.1 applied an SE-30 column (2.5 ). During studies on the metabolism of tropane alkaloids, whereby quantitative determinations of minor alkaloids were carried out, Achari and Newcombe4 used columns with SE-30 (2 %), XE-60 (2 %), Versamid (5 %), QF-1 (2.5 %) and PEGS... 

Santoro et al. 1 worked out a similar method for the quantitative determination of scopolamine in pharmaceutical preparations containing i.a. phenylpropanolamine and chlorpheniramine after extraction of the free base and using homatropine as an internal standard. The scopolamine content was less than 9 % of the total belladonna alkaloids present in the preparation. 

Windheuser et al. prepared the trimethyl silyl derivatives of the alkaloids by means of N,0-bis(trimethylsilyl)acetamide in an N,N-dimethylformamide solution of the alkaloids. In this way they carried out quantitative determinations of scopolamine and its acidic and basic... 

For analysis of the alkaloids present in cuboisia species, Griffin et al. converted the alkaloids after extraction and purification into their trimethylsilyl derivatives to prevent dehydration to the apo-form. Quantitative determinations were carried out on a 1.5 % SE-30... 

The gas chromatography of cocaine has mainly been dealt with in connection with investigations to develop selective and sensitive methods for its detection and quantitative determination in pharmacological and toxicological analysis. One study has so far been done on naturally occurring alkaloidal mixtures present in the coca plant (Erythroxyion coca Lam.). ... 

Midha and Charette carried out quantitative determinations of quinidine in plasma and whole blood. Cinchonidine was added to the plasma sample to be analyzed as an internal standard. The alkaloids were extracted with benzene at pH 12.0. The residue from the extract was mixed with 25 yl of trimethylanilinium hydroxide in methanol, and aliquots (1-2 ul) were injected into the gas chromatograph in which the injection port was held at 350°C. The methyl derivatives of quinidine and the internal standard gave well separated symmetrical peaks. Detection by flame ionization gave a linear response over the range 0.2-12.0 vg quinidine/ml plasma. The limit of detectability was 0.05 ug/ml and the method was adequate for following blood profiles of 200 mg quinidine sulphate doses in humans. The recovery of quinidine... 

Doetsch et al. used gas chromatography for the separation of the non-phenolic alkaloids and for the quantitative determination of mescaline in Pereskia, Pereskiopsis and isiaya species. A packed 1.5 t 0V-101 on Chromosorb G column and a column temperature of 150°C was used for the analysis. 

Yamasaki et al. applied gas chromatography to the separation and quantitative analysis of the alkaloids in some Ephedra species collected around the Himalayas. A satisfactory separation of the alkaloids and quantitative determination of L-ephedrine and D-pseudoephedrine was achieved using oxazolidine formation with acetone. ... 

The opium alkaloids have engaged the interest of scientists since the isolation of morphine by Sertlirner in 1806. The Isolation, characterization and quantification of these alkaloids have been a continuing challenge. Gas chromatography of opium alkaloids has been performed i.a. for the analysis of the alkaloids present in the crude drug itself, especially for the quantitative determination of morphine, as well as for the analysis of opium alkaloids, mainly morphine - and heroin - in biological materials. Most studies have so far been carried out with packed columns, only a limited number with capillary columns. 

A number of various derivatization reactions have been used, as shown in Table 14.25. The derivatization has been carried out as off-column or on-column derivatization, mostly in order to give morphine and related alkaloids with phenolic or alcoholic hydroxyl groups better gas chromatographic properties. Especially for quantitative determination of morphine in opium or biological material such derivatization was necessary. Street et al. found, however, that the problem of adsorption of a phenolic alkaloid, such as morphine, because of "active sites" on the solid support could be solved by deactivation of the solid support by treatment of it (diatomaceous earth) with benzoyl chloride in pyridine before coating it with the stationary phase. 

For quantitative determination of heroin in illicit samples in the presence of alkaloids... 

Forni described a method for quantitative determination of ajmaline in bark and root samples of Rauwoifia vomitoria. Because of the presence of many products in the raw methanoltc extract of the crude drug, an extraction of the acidified extract was performed with chloroform prior to extraction of the alkaloids with the same solvent after adjustment of the pH to 8.5. Because of the polarity of the alkaloids, they were silanized before gas chromatography on a 3 % 0V-17 on Chromosorb U column. A gas chromatogram showing the good separation of ajmaline from other alkaloids with similar structures and arbutin, which was used as an internal standard, is found in Figure 17.6. 

Sondack and Koch carried out quantitative determinations of strychnine and brucine in pharmaceutical preparations using OV-I and a glass column. Papaverine was used as an internal standard. The alkaloidal bases were extracted with chloroform after adding sodium hydrox-... 

Vincent and Engelke carried out an isocratic HPLC separation of the five major opium alkaloids in Papaver sornniferum and of thebaine in P. braeteatum on microparticulate silica gel for a quantitative determination of the alkaloids. A mobile phase consisting of four components n-hexane - dichloromethane - ethanol - diethylamine (300 30 40 0.5) separated the five major opium alkaloids (TABLE 7.7, Fig. 7.12). By altering the ratio dichloromethane - ethanol, the retention of the alkaloids could be varied. Capsular tissue extracts could be analyzed directly. 

For quantitative determinations of ergot alkaloids, Wurst el al. made use of several... 

Using a 1/8", 5, 5 SE-30 Chromosorb W column operated at 230°C. and at 2 0°C., Parker, Fontan and Kirk77 separated meperidine from other alkaloids, barbiturates, sympathomimetic amines and tranquilizers. This work was directed towards development of a screening process rather than quantitative determination. 

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