High-performance liquid data processing

The resolution of a multicomponent system involves the description of the variation of measurements as an additive model of the contributions of their pure constituents [1-10]. To do so, relevant and sufficiently informative experimental data are needed. These data can be obtained by analyzing a sample with a hyphenated technique (e.g., HPLC-DAD [diode array detection], high-performance liquid chromatography-DAD) or by monitoring a process in a multivariate fashion. In these and similar examples, all of the measurements performed can be organized in a table or data matrix where one direction (the elution or the process direction) is related to the compositional variation of the system, and the other direction refers to the variation in the response collected. The existence of these two directions of variation helps to differentiate among components (Figure 11.1). 

Based on the quantity of data and the complexity of the process, an enterprise operational informatics system must be robust and scalable. It should also integrate with analytical instrumentation such as high performance liquid chromatography (HPLC) MS to verify compound identity. A recent review of HTS informatics provides a compact overview of the key informatics elements of HTS operations and data handling (Ling, 2008). 

High-performance liquid chromatography (HPLC) provides an excellent platform to carry out these measurements. The computer-controlled HPLC with automated sample handling, injection and computerised data acquisition and processing makes possible the measurement of hundreds of samples per week without too much manual work. The measurements are made by running overnight and at weekends so this requires... 

Willson et al. (13) note that most analytical techniques (e.g., high-performance liquid chromatography [HPLC]) look specifically for the arrival of a single product of the reaction (or loss of a reactant), and they are therefore not necessarily of value in investigations of intermediates in the reaction process, but that isothermal microcalorimetry follows the entire process (see earlier text). By comparison of calorimetric data and analytical data, it was possible to propose a sequential reaction mechanism for ascorbic acid oxidation that could not be determined simply from analytical data. 

Figure 21.6 shows the kinetic profile under the actual process conditions. The reaction profile (combination of the anion and free acid of 3 versus time) obtained by high-performance liquid chromatography (HPLC) analysis also matched the onfine IR data. Again, the use of online IR coupled with principal component analysis provided the means to profile HA and A during the reaction. Formation of the free acid form 3 (HA) was immediately observed upon addition of a catalytic amount of TFA. This clearly shows that constant liberation of the free acid form HA... 

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