Analytical dilemmas

Chemical, biochemical and biological models of alkaloid biogenesis can only be constructed according to scientific research on the small chains of the synthesis of each alkaloid, and enzyme and gene involved in these chains. Models are constructed from the experimental data on synthesis and degradation of alkaloids. 

Another analytical dilemma is the problem of in vitro and in vivo conditions. Alkaloids should be studied in their physiological conditions in organisms. This is not possible in many cases. In vitro experiments give compromised data. Theoretical conclusions and hypotheses in analysis, although they are in many cases indicators of a new breakthrough, also have some problems and some risks. 

Analytical dilemmas are one reason why continuous novelization of structural, biochemical and molbiological results is necessary. These dilemmas merit attention nowadays, more than 200 years after the first alkaloid was isolated. 

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 .  

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This analytical dilemma and the non-conformity of test results obtained for complex, heterogeneous measurands stimulated a movement towards standardization implemented by various international organizations such as the IFCC (Table 6). All these efforts tried to follow metrologically established rules according to the International Vocabulary of Basic and General Terms in Metrology (VIM) [38] and ISO-CEN standards (Table 7)... 

The understanding of foam persistence, or stability, and bubble coalescence is an analytic dilemma. Unquestionably, this is a dynamic... 

Ions at m/z 55, 60, 214 and 236 are observed but do some or all of these arise from the background and are present throughout the analysis, or are they present in only a few scans, i.e. are they from a component with insufficient overall intensity to appear as a discrete peak in the TIC trace An examination of reconstructed ion chromatograms (RICs) from these ions generated by the data system may enable the analyst to resolve this dilemma. The TIC shows the variation, with time, of the total number of ions being detected by the mass spectrometer, while an RIC shows the variation, with time, of a single ion with a chosen m/z value. The RICs for the four ions noted above are shown in Figure 3.15. These ions have similar profiles and show a reduction in intensity as analytes elute from the column. The reduction in intensity is a suppression effect. 

The last approximating step leading to Equation 8.56 illustrates the dilemma that one faces in the application of perturbation theory. The resulting equations are analytical, which in principle provides insight by inspection into the physical causes... 

The writing of an analytical profile of aspirin, this drug of drugs, poses two major dilemmas. The first is in the name itself. There are many countries where Aspirin is still a trade-name of the German firm Bayer AG, and Acetylsali-cylic Acid is used as the generic. Yet, I decided to use the former because it is the U.S.P. and B.P., the better known worldwide and the more elegant name. 

An important consideration for quality control in industry and commerce relates to the trend of developing faster analytical methods than those described in official sfandards the question in such cases is whether a proposed method is acceptable as replacement for the standard. This problem relates to the concepts fitness for purpose and measurement uncertainty, the latter serving for the estimation of the LOD and LOQ parameters of analytical quality. An example of this dilemma relating to the peroxide value is discussed in Section IV.B.5. 

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