Alkaloids Determination

Chromatograph standards and samples as described in Section 3.1.6. Likewise, obtain integrated peak areas and construct calibration curve from analyte-to-NEN peak area ratios. 

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There are no very recent papers dealing with Chincona alkaloid determination in the literature. Table 8 reports some of the most significant works in this field. 

The feeding behavior of herbivorous insects is guided by plant chemistry. There are specialists and generalists with regard to the range of plant species they attack. Nutrients such as sugars and proteins, and secondary plant compounds such as phenolics, terpenoids, or alkaloids, determine whether or not an insect will feed on a plant and to what extent. 

Possibly as a result of the social implications of the hallucinogenic j5-phenethyl-amines and simple isoquinoline alkaloids, a large number of new plant species suspected to contain these structural types have been closely scrutinized with the aid of sensitive analytical methods. Thus, extensive screening of a large variety of cactus species has been carried out. G.c. analysis has indicated the presence of trace amounts of dimers and trimers of phenethylamine and tetrahydroiso-quinoline types " while combination g.c.-mass spectrometry has enabled rapid identification of alkaloids of 120 cactus species." High voltage electrophoresis has been used for quantitative alkaloid determination.Useful structural information may be obtained from the technique of chemical ionization mass spectrometry. ... 

It is surprising that the activities of these two alkaloids, determined by the dose-activity relation for head-drop, diminish appreciably within hours and become constant only after one to two months. These alkaloids seem to change... 

Leading chemical references may be obtained from a recent review. A review of the analytical methods of purine alkaloid determination is not readily accessible. Caffeine has been isolated from Banisteriopsis inebrians, a species which also produces simple indole alkaloids. ... 

USE As acid-base indicator in 0.2% soln in alcohol. pH 4.4 red 6.4 blue. Satisfactory for titrating mineral acids, strong bases, many alkaloids determining alkalinity and temporary hardness in water analysis. Biological stain dye for wool, silk- Not adapted for carbonates, weak inorganic and organic acids, weak bases. Lacmoid is more sensitive than litmus, particularly in form of test paper. 

Several studies have been reported on the mechanism of chiral catalysis by modified solid catalysts. Both modifier and substrate structures play important roles. Refer to reviews by Fish and Ollis (1978), Izuma (1983), Sachtler (1985), Tai and Harada (1986), and Blaser et al. (1988) for details of various postulated mechanisms, but one particular conclusion is significant. For the cinchona-modified platinum catalyst, the presence of nitrogen is considered essential, and the configuration at Cg of the alkaloid determines which enantiomer of the product is formed. 

Analysis is most efficient with a Griffith Still which consists of a series of six stills connected together with a master electrical control. An experienced operator can run 40 samples/h (Griffith and Jeffery 1948 Griffith 1957). The Griffith method is an AO AC (Association of Official Analytical Chemists)-approved method for determination of total alkaloids in tobacco (Williams 1984). Steam distillation is not the method of choice for determining secondary alkaloids which include nornicotine, anabasine, anatabine, and myosmine. In cases where individual alkaloids in a sample must be analyzed, steam distillation is not dependable. However, in cases where total alkaloids determined as nicotine will suffice, steam distillation is adequate and the use of more sensitive equipment is not necessary. 

There are a wide variety of methods available for the analysis of alkaloids in tobacco. Each method is associated with certain advantages and disadvantages, but fills a certain niche for tobacco scientists. If the percent total alkaloids determined as nicotine suffices, then steam distillation or autoanalyzer are appropriate methods. When secondary alkaloids need to be quantitatively determined, then one of the chromatographic methods is more appropriate. 

Preparation of Concentrated Poppy Straw (CPS) and Alkaloid Determination. Dried poppy straw (20 g) is extracted in a Soxhlet apparatus with MeOH (12h), concentrated to a pasty mass and treated with 0.25 g Ca(OH)2 and 2.5% acetic acid solution (5 ml). The mixture is centrifuged and the supernatant separated and filtered. This process of extraction is repeated three times to obtain the CPS, which is then made up to 10ml solution in a volumetric flask with the acetic acid solution. 

A typical countercurrent chromatogram of an alkaloid extract from endophyte-infected tall fescue seed is shown in Figure 3. Two curves are superimposed the solid line represents mg of loline-t)rpe alkaloids determined by GC analysis, and the dotted line represents absorbencies at 312 nm, which is characteristic of... 

Identified peaks 1, lysergic acid amide (670 /ig) plus isolysergic acid amide (520 fig) 2, N-methylloline (61 mg) 3, N-acetylloline (305 mg) 4, ergonovine (55 /ig) 5, N-formylloline (601 mg) 6, loline (31 mg) plus N-acetylnorloline (28 mg). Loline-type alkaloids determined by GC. Ergot-type alkaloids determined by HPLC with fluorescence detection and expressed as /ig ergotamine tartrate. 

Fig. 154). In the quantitative determination, the spots were scraped off the plate [silica gel G (Merck)], eluted with methanol, the eluate made up to 5 ml and the concentration of alkaloid determined from the light absorption (wave lengths used were narcotine 312 nm, morphine 286 nm, thebaine 285 nm, papaverine 279 nm and codeine 215 nm). Steele [230 b] has recently achieved good separations of opiates in narcotic seizures, using silica gel G layers. The i /-values of 26 compounds were evaluated in eight solvents the best solvents were found to be ethyl acetate-benzene-acetonitrile-ammonium hydroxide (50 + 30+ 15 + 5) and acetonitrile-benzene-ethyl acetate-ammonium hydroxide (40 + 30 +25 + 5).. ...

The U.S.P, method of morphine assay is somewhat cumbersome but the alkaloid is finally titrated if sufficient sample (100 ml) is available the B,P. method may be followed until evaporation of the chloroform-ethanol mixture and then the alkaloids determined by solution in excess of 0 02N acid and back-titration after boiling the solution, using methyl red as indicator (1 ml 0-02N — 0 005707 g anhydrous morphine). 

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