Alkaloids, analysis

These analytical dilemmas interfere with the methods of alkaloid analysis. Each group of alkaloids has its own methods of extraction, isolation and crystallization, as well as detection in structure, molecule and dynamicity. Not all these stages are still possible in the majority of alkaloids. In recent years, many techniques have been used in alkaloid detection. There are atomic and molecular electronic spectroscopy, vibration spectroscopy and electron and nuclear spin orientation in magnetic fields, mass spectroscopy, chromatography, radioisotope and electrochemical techniques. Although important developments in methodology and... 

The first method of alkaloid analysis was developed in 1805, in the case of morphine. This method of isolation, with minor and major variations, is still used today. By this method, the first quinolizidine alkaloids were also extracted sparteine in 1851, lupinine in 1865 and lupanine 2 years later. At the beginning of the 20th century, the extraction and determination of total quinolizidine alkaloids in the same analysis (common) was carried out by Jurkowski , Nowotndwna, Trier272, ivanov °, Sengbusch , Lukaszewicz , Wuttke . Reifer and Niziolek and Wiewiorowski and Skolik initiated research in which the sum of the contents of the different and separate alkaloids is the total alkaloid content. The method of isolation of quinolizidine alkaloids was developed next by Wysocka et and Wysocka and Przybyl . ... 

The idea of calorimetry is based on the chemical reaction characteristic of molecules. The calorimetry method does not allow absolute measurements, as is the case, for example, with volumetric methods. The results given by unknown compounds must be compared with the calibration curve prepared from known amounts of pure standard compounds under the same conditions. In practical laboratory work there are very different applications of this method, because there is no general rule for reporting results of calorimetric determinations. A conventional spectrophotometry is used with a calorimeter. The limitations of many calometric procedures lie in the chemical reactions upon which these procedures are based rather than upon the instruments available . This method was first adapted for quinolizidine alkaloid analysis in 1940 by Prudhomme, and subsequently used and developed by many authors. In particular, a calorimetric microdetermination of lupine and sparteine was developed in 1957. The micromethod depends upon the reaction between the alkaloid bases and methyl range in chloroform. 

The use of electrophotometry requires a sample preparation with a coloured solution. Together with an electrophotometer for alkaloid analysis, a constant light intensity and filter, as well as an electronic installation for measurement, must be used. The electrophotometry method is an application of both calorimetry and photometry in the same analysis. 

The stationary phase may be a solid or liquid on a solid support. The mechanisms responsible for distribution between phases include surface absorption, ion exchange, relative solubilities and steric affects . High performance liquid chromatography is a useful method for quinolizidine alkaloid analysis, especially when pure standards are available". This method was recently used for alkaloid metabolite extraction and analysis . A simple reversed-phase liquid chromatographic method has been developed for the simultaneous quantitation of four anticancerous alkaloids vincristine, vinblastine, and their precursors catharanthine and vindoline using a specific HPLC column . 

Gas-liquid chromatography is a qualitative, but also quantitative, method of alkaloid analysis. It is very sensitive. The only problem concerns the distribution of the alkaloid mixture in the chromatographic process and the identification of alkaloids, which must be achieved by a different technique . A very positive characteristic is the possibility of totally computerizing this method of alkaloid detection. 

Quinolizidine alkaloid analysis also utilizes the X-ray method, which is based on the absorption of X-rays, diffraction of X-rays, wavelength, and radiant power measurements of X-rays. When an atom is excited by the removal of an electron from an inner shell, it usually returns to its normal state by transferring an electron from some outer shell to the inner with the consequent emission of energy as an X-ray. The X-ray method is applied to quinolizidine alkaloids which have a crystalline form. In this sense it is the same as the RTG methods, which can be applied only to crystalline materials. X-rays can be absorbed by material and this gives rise to X-ray absorption spectra . The spectrum provides material for the identification of compounds. 

Enzyme-linked immunosorbent assay is a heterogenous immunoassay. Reactions involve a solid phase to which components are sequentially presented and successively bound. This method is very effective in the determination of the total alkaloid content. The positive characteristics of this method are the use of non-toxic reagents and basic equipment with low costs, a small sample volume and the ability to measure alkaloids in crude sample extracts. According to the literature, compared with results obtained from GLC, the precision of ELISA for quinolizidine alkaloids is not as high as that of the gas chromatography procedure, but is adequate for plant breeding purposes. The use of enzymes in developing the methods of quinolizidine alkaloids analysis looks likely to increase in the future. 

There exists a long list of different methods of quinolizidine alkaloid analysis (Table 21). These methods are of a chemical and biological nature. The development of methods of alkaloid analysis has been a long and difficult process. 

A further problem which must be resolved is the resistance of quinolizidine alkaloids to other amines and nitrogen compounds during the analysis. The general conclusion is that a perfect method of alkaloid analysis does not exist. Therefore, the explanation of results in the light of the above-mentioned factors is vital in each case. 

The history of the use and development of methods of analysing quinolizidine alkaloids shows a move away from the deployment of iodine towards the use of complicated biological processes, such as antialkaloid antibody and enzymatic processes. It seems to be necessary to incorporate biological methods of alkaloid analysis into the system of analytic-chemical monitoring used in modern laboratories. 

Aniszewski, T. 1994. From iodine to enzyme A critical review of chemical and biological methods of lupine alkaloids analysis. Science of Legumes, 1 25-36. 

Table 5 Tropane alkaloid analysis in plasma or serum by LC-MS and LC-MS/MS for pharmacokinetic studies... 

Fig. 2 Simultaneous LC-MS/MS analysis of diverse tropane alkaloids. Analysis of plasma samples was performed according to John et al. [50] using an Atlantis T3 C18 column (150 mmx4.6 mm I.D., 5 pm) in gradient mode (as indicated) with solvent A (0.1 %v/v FA) and solvent B (ACN/water 80 20 v/v 0.1% v/v FA) at 1 ml/min and 30 °C. Detection was done by positive ESI MS/MS in MRM mode...

Aehle E, Drager B (2010) Tropane alkaloid analysis by chromatographic and electrophoretic techniques an update. J Chromatogr B 878 1391-1406... 

Current methods for tropane alkaloids analysis have been well covered in the literature. An excellent comprehensive review written by B. Drager [45] appeared in 2002, describing the analysis of tropane and related alkaloids in plant material. Sample preparation procedures were reviewed, as well as the analytical methods used for performing the separation and detection of tropane alkaloids, such as gas chromatography (GC), liquid chromatography (LC), and capillary electrophoresis (CE). Therefore, this chapter will not describe in detail these well-known analytical methods but discuss some recently developed applications for the analysis of tropane alkaloids in plant material and biological matrices. 

PRECISION OF QUANTITATIVE ALKALOID ANALYSIS ON TOBACCO SAMPLES OF DIFFERENT ALKALOID COMPOSITION15... 

A quantitative comparison of alkaloid analysis using gas chromatography and steam distillation is given in Table 5.7. 

QUANTITATIVE COMPARISON OF ALKALOID ANALYSIS USING GAS CHROMATOGRAPHY AND STEAM DISTILLATION15... 

So far HPLC analysis of alkaloids has been performed by means of ion-exchange, reversed-phase, ion-pair and straight-phase chromatography. Also, some general aspects of the alkaloid analysis by means of these types of chromatography will be dealt with in this chapter. 

Reversed-phase chromatoqraphy has most widely been used in HPLC alkaloid analysis - particularly on microparticulate silica qel with chemically bonded alkyl qroups, i.e. octyl and... 

To overcome the problem of tailing in reversed-phase HPLC, salts can also be added to the mobile phase - so-called ion-suppression. Ammonium carbonate, sodium acetate and sodium phosphate have been used for this purpose in the analysis of alkaloids. Also, ion-pairing has proved to be successful in alkaloid analysis. It allows analysis of alkaloids under acidic conditions, thus avoiding the problem of chemisorption of the basic compounds on the acidic silanol groups. 

A number of papers have been published on the HPLC analysis of alkaloids in order to study the possibilities for such analyses in general. The papers comprise a wide variety of alkaloids and HPLC systems for their separation. The data published in these papers may be useful in connection with many separation and other HPLC problems in the analysis of alkaloids. Therefore some of the data of general interest are summarized in the present chapter. However, in other chapters of this book, HPLC systems that may be useful for alkaloid analysis in general, have also been dealt with (see Table 2.1). 

Coc,23 other alkaloids Analysis alkaloids Merckosorb Si60,5um 300x2 CHCl,-MeOH(9 l),(8 2),(7 3) Et20 Me0H(8 2),(7 3),(6 4) 5... 

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