Analysis strategies parallel processing

A second strategy relies on parallel experimentation. In this case, the same experimental step is performed over n samples in n separated vessels at the same time. Robotic equipment such as automated liquid-handlers, multi-well reactors and auto-samplers for the analysis are used to perform the repetitive tasks in parallel. This automated equipment often works in a serial fashion as, for example, a liquid handler with a single dispensing syringe filling the wells of a microtiter plate, one after another. However, the chemical formation of the catalyst or the catalytic reaction are run at the same time, assuming that their rate is slow compared to the time needed to add all the components. The whole process appears parallel for the human user whose intervention is reduced. 

However, problems associated with the reproducibility between electrodes derived from the screen-printing process and the partial electrode fouling have compromised the sensitivity of the biosensors. Work is in progress to improve both the reproducibility and the limits of detection by the use of new types of electrodes. The toxin overestimation observed with the amperometric biosensor, in the case of the microcystin analysis, suggests the use in parallel to other analytical techniques in order to minimise the risk of false-positive results. Nevertheless, the electrochemical strategy is appropriate to discriminate between toxic/non-toxic samples. 

In this chapter we will discuss current approaches for analytical characterization of combinatorial libraries in a pharmaceutical industry environment. Recently, several analytical groups have presented very similar strategies for analysis of libraries [7-9]. As will be shown later, the key to successful analytical characterization of a combinatorial library is to perform analytical and chemical work in parallel with the library development. The accumulation of data and analytical experience during this process results in an assessment of library quality with a high level of confidence, even if as little as 5-10% of the library components are analyzed. Utilization of the strategy will be demonstrated using two examples analysis of a library synthesized on a robotic station in spatially addressed format and analysis of a library synthesized in accordance with split-and-mix technology. 

A strategy to develop new catalysts or to improve existing ones must encompass at least three aspects (i) an analysis of the catalyst structure and composition, (ii) an analysis of the interactions of reactants and products with the catalyst surface, and (iii) characterizations that should be performed under conditions as close as possible to those of the technological process, ideally as the catalyst is working and rates are measured simultaneously. It is difficult to meet all of these requirements in a single experiment, but the necessary information can be obtained in parallel investigations, and spectroscopy of the working catalytic surfaces and molecules adsorbed on them is thus the focus of much current research (7). 

The synthetic throughput achievable by the medicinal chemist (having adopted parallel synthesis strategies) has rendered analysis and purification one of the key (and possibly rate-limiting) steps in the discovery process. Although advances in sample analysis throughput have been clearly demonstrated, there is a limit as to how fast a separation and analysis can be achieved... 

Unfortunately, automated parallel analytical separation systems were commercially not available at this time. However, in seeking to create the parallel strategy, we initiated studies on a manual-based injection system to validate the approach. It was thus possible to develop a manual parallel analytical separation system that allowed two columns to be used for the analysis of two samples concurrently. If this process could be automated and a greater number of analytes could be examined simultaneously by the same methodology, a quantal leap in productivity could be achieved. As previously discussed, the sample presentation typically occurs in an MTP format and so the simultaneous parallel analysis of a column or row from such a plate would seem a logical approach. 

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