The impact of continuous processing

1 Context - a brief history of drug impurity analysis 

The pharmaceutical industry has traditionally been one of the major drivers for innovation in organic chemistry analysis. There are several reasons for this need for careful characterisation of the products of the industry, which will be explored briefly in this section. 

Technique Property measured Comments Suitability for on-line analysis 

Microwave Molecular rotation More often used for putting energy into a reaction than for measurement Sensitive not diagnostic requires engineering of waveguides 

IR Bond vibrations (change in dipole moment) In principle contains wealth of structural infonnation, but difficult to extract in practice Fairly sensitive and specific broadly applicable new fibre optics wiU increase suitabdity 

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It is anticipated that micro-instrumentation will allow for effective evaluation and eventual use of continuous processes in areas where batch approaches have been traditional. The expected impact of this will be significant on energy savings and in environmental and productivity aspects of commercial processing. The areas where this will show early benefits are in pharmaceuticals, but it is envisioned that biotechnology will incorporate the advantages of continuous processing. This will have a broad impact on medicinal bio-products as well as biochemical and biofuel production. 

During the EFA s Rebuttable Presumption Against Registration (RPAR) process (now called Special Review), it became apparent that if uses of certain pesticides with identified potentials for causing adverse effects were to be continued, user exposure data would be needed that demonstrated minimal exposure hazards when certain use procedures were followed. Scientists of both the EPA and the Scientific Advisory Panel (SAP) to EPA then realized that they could not make satisfactory risk assessments and evaluate the impact of continued use without actual workplace exposure data. 

Specific reactor characteristics depend on the particular use of the reactor as a laboratory, pilot plant, or industrial unit. AH reactors have in common selected characteristics of four basic reactor types the weH-stirred batch reactor, the semibatch reactor, the continuous-flow stirred-tank reactor, and the tubular reactor (Fig. 1). A reactor may be represented by or modeled after one or a combination of these. SuitabHity of a model depends on the extent to which the impacts of the reactions, and thermal and transport processes, are predicted for conditions outside of the database used in developing the model (1-4). 

In order to understand the impact of pollution on Earth, we must realize that the planet itself is not stagnant, but continually moving material around the system naturally. Any human (anthropogenic) redistribution in the elements is superimposed on these continuous natural events. Energy from the sun and radioactive decay from the Earth s interior drive these processes, which are often cyclic in nature. As a result, almost all of the rocks composing the continents have been processed at least once through a chemical and physical cycle involving... 

Calculations of economic profitability can only be predictive in the phase of process development, before a plant is on stream for a long time. Therefore, individual components of costs and market evaluations will bear some uncertainty. This uncertainty is relatively high for pharmaceuticals and agrochemicals. The impact of these uncertainties on the profitability of a process may be quantified by a sensitivity analysis. This analysis provides information about the sensitivity of the process economics to changes in parameters relevant for the profitability (investment costs, price and consumption of raw materials, utility unit costs, product value and demand, etc.), and therefore on the reliability of the result of the economic evaluation. In the early stages of process development, a high sensitivity indicates the areas requiring attention for continued R D work. 

Later developments which have had more impact on copper smelting relate to an approach which combines roasting, smelting and converting steps in one reactor, thereby making the copper production process continuous. The three unique continuous processes tried in operation are (i) the Worcra process, (ii) the Noranda process and (iii) the Mitsubishi process. The principles of the processes are respectively shown in Figures 4.5 to 4.7. 

In view of the different manifestations of psychopathological behaviors found in diverse groups that cannot be adequately accounted for by factors concerning race, ethnic group or the acculturation process, Agbayani-Siewert et al. (1999) put forward a model that allows direct examination of the impact of cultural factors on psychopathological manifestations, while continuing to include structural social factors. 

Copper production is quite a complex process to plan and to schedule due to the many process interdependencies (shared continuous casters and cranes, emission level restrictions, limited material availability, to name a few). This makes it very difficult to foresee the overall consequences of a local decision. The variability of the raw material has alone a significant impact on the process, various disturbances and equipment breakdowns are common, daily maintenance operations are needed and material bottlenecks occur from time to time. The solution that is presented here considers simultaneously, and in a rigorous and optimal way, the above mentioned aspects that affect the copper production process. As a consequence, this scheduling solution supports reducing the impact of various disturbance factors. It enables a more efficient production, better overall coordination and visualization of the process, faster recovery from disturbances and supports optimal... 

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