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NORMAL-PHASE HPLC. Among the various modes of HPLC, reversed-phase and normal-phase chromatography (NPC) are employed most commonly in separation. Normal-phase chromatography was the first liquid chromatography mode, discovered by M. In this chapter we describe a simplified overview of the theory and practice of normal-phase chromatography.. 5.2 THEORY OF RETENTION IN NORMAL-PHASE CHROMATOGRAPHY. As the polarity of the mobile phase...
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6.1 SEPARATION OF THE ANALYTE MOLECULES BY THEIR SIZE. The separation process in simplified form is based on the ability of sample molecules to penetrate inside the pores of packing material and is dependent on the relative size of analyte molecules and the respective pore size of the absorbent. The process also relies on the absence of any interactions with...
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Specific require- ments or methodologies for validation depending on the life cycle of the potential drug candidate in each specific area in the drug development process will be addressed in the corresponding chapter.. Quantitative measurements of the content of related substances*. As development of the project progresses and as more analytical and product-specific information is acquired, the analytical methods evolve...
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This includes standard analytical procedures of peak integration, calibration and quantitation, and more complex correlation of the retention dependencies with variation of selected parameters.. Selection of the starting conditions for method development by using information of similar separations. Optimization of the existing method, to speed up the analysis, increase ruggedness of the chromatographic method, and so on. With the present...
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Focus within the pharmaceutical industry has been to increase the likeli- hood of successfully developing clinical candidates by optimizing the compo- nents of the discovery process (i.e., spanning target identification → chemical. Once considered primarily an enabling tool for medicinal chemists, HPLC and LC/MS are now key technologies incorpo- rated at just about every stage of the drug discovery process....
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Lipinski has referred to this analysis as “rule of five” because the cutoffs for each of the four parameters were all close to five or a multiple of five. The absorption of drug molecules in the gastrointestinal tract is dependent upon the pK a of the compound and the pH of the gastrointestinal region (Figure 12-2). Almost 63% of all...
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Herein, we present an overview of the above techniques accompanied with several examples of the use of liquid chromatography–. (ii) the isolation and purification of the active ingredients of medicinal plants or microorganisms to screen their spectrum of. or (iii) the serendipitous discovery of a com- pound with a novel pharmacological action (e.g., the accidental discovery of antidepressants). Today, one...
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14.1 RESPONSIBILITIES OF THE ANALYTICAL CHEMIST DURING PROCESS DEVELOPMENT. Economic factors will dictate minimization of the synthe- tic steps, maximization of yield, and choice of raw materials. To this end, HPLC is a critical tool to perform many of the above tasks. In-depth discussion of the theory and method development of RPLC, ion exchange, and NPLC are highlighted in the...
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The formula, in the current case, is a pharmaceutical dosage form. The entire process starts early in the preformulation stage (covered in Chapter 12) and continues until the final market image is devel- oped and launched (after approval from health authorities). Generally due to limitations in the availability of an API and to minimize development time, this formulation is not...
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16.1 INTRODUCTION. One of the most important analytical technology transfers is high-performance liquid chromatography (HPLC) methods. Depending on the structure of the pharmaceutical organization, trans- fer of analytical technology and manufacturing may occur at the end of the phase II clinical studies or during the transition from phase II to phase III.. A prerequisite for the transfer of analytical technology...
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To understand how to optimize a separation for speed, it is worth revisiting some of the theoretical concepts developed earlier in this text. where L is the column length, u is the linear flow velocity of the mobile phase, and k is the retention factor of the latest-eluting peak. Notice here some obvious ways to increase the speed of analysis:...
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18.1 THE INFLUENCE OF TEMPERATURE ON CHROMATOGRAPHY. For much of the early development of liquid chromatography, separations were carried out at ambient temperature and many laboratories did not attempt to regulate or control the temperature of the column. Frequently, the column would be mounted on the side of the pump or detector and thus would be subjected to changes in...
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For example, INTRON A (interferon α-2b) is one of the first recombinant protein drugs introduced on the market. TNF is one of the chemical messengers that are involved in the inflammatory process. The therapeutic proteins and the drug target proteins are usually asso- ciated with post-translational modifications, such as phosphorylation [4], glycosylation [5], aggregation, and disulfide bond formation [6], with...
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LC-NMR OVERVIEW AND. However, conventional detectors used to monitor the separation, such as UV, refractive index, fluorescence, and radioactive detectors, provide limited infor- mation on the molecular structure of the components of the mixture. NMR is widely recognized as one of the most important methods of structural elucidation, but it becomes cumbersome for the analysis of complex mixtures that require...
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“the separation technique of the 20th century” [4]. This situation changed dramatically in the 1960s with the theoretical understanding of the chromatographic process, the development of high-performance liquid chromatography, and the synthesis of highly selec- tive stationary phases. Since chromatography scales up linearly and independently from the selected technology (rationales when making a choice will be given later on), the...
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In the late 1950s/early 1960s, many of the drugs were synthesized and used in a racemic form. Furthermore, unequal detector response of the diastereomers must be corrected via stan- dard procedures [7]. In the adsorbed state, a parallel alignment of the planar amide group and the surface of silica gel is preferred.. Extra valida- tion is required to establish the...