Data Acquisition Multiple measures

With this focus on CYP and fiver metabolism, most companies have established high throughput assays to measure compound stability in the presence of human (or preclinical species) fiver microsomes [49]. Disappearance of starting compound from an incubation with microsomes is monitored. Measurement at a single time point enables a rank-ordering of compounds for stability based on percent of parent compound remaining acquisition of data at multiple time points allows determination of half-life, intrinsic clearance, and extrapolation to a predicted in vivo clearance [50]. 

Selected entries from Methods in Enzymology [vol, page(s)] Analysis, software for, 207, 717 barrier models, 207, 818 closed and open time estimation, 207, 755 data acquisition, 207, 747 modal behavior analysis, 207, 757 multiple channel problem, 207, 756 single-channel [extraction of kinetic information, 207, 765 measurement in tissue slices, 207, 220] synaptic, resolution improvement in patch clamp recording, 207, 216 whole-cell recording in calcium channel, 207, 181 fluctuation analysis, 207, 192. 

The available data from emulsion polymerization systems have been obtained almost exclusively through manual, off-line analysis of monomer conversion, emulsifier concentration, particle size, molecular weight, etc. For batch systems this results in a large expenditure of time in order to sample with sufficient frequency to accurately observe the system kinetics. In continuous systems a large number of samples are required to observe interesting system dynamics such as multiple steady states or limit cycles. In addition, feedback control of any process variable other than temperature or pressure is impossible without specialized on-line sensors. This note describes the initial stages of development of two such sensors, (one for the monitoring of reactor conversion and the other for the continuous measurement of surface tension), and their implementation as part of a computer data acquisition system for the emulsion polymerization of methyl methacrylate. 

The use of multiple detectors with size-exclusion chromatography (SEC) can greatly increase the information content available from a typical SEC analysis. This multidetector approach permits more accurate measurement of polymer properties than conventional SEC. The additional information, however, is obtained at the expense of an increase in the complexity of the instrumentation and data handling. In particular, a number of concerns arise in data acquisition and processing that are not present in conventional SEC. Some of these difficulties are outlined, and possible solutions are discussed. 

Regardless of the selection of the scan mode (see sections 3.6.8 and 3.6.9), the intensity recorded at each Bragg angle is measured during a certain period of time - counting time - which is one of the multiple user-specified parameters in the data acquisition process. As clearly seen in Figure 3.47, the importance of the counting time parameter is difficult to overestimate since it directly influences the accuracy of the measured diffracted intensity, and the overall quality of diffraction data. 

With respect to mass spectral matching, the criteria for identification vary depending on the technique used for mass spectral data acquisition (see summary of requirements in Table 8). It is interesting to note that while the FDA does not rule out the use of exact mass measurements, it views these data as problematical as there are no generally accepted specific standards for their use. The problem here is that it is difficult to be definitive about the resolving power required, particularly, when analytes have masses greater than m/z 500. Clearly the resolving power and accuracy must be sufficient to exclude all reasonable alternative elemental compositions and they recommend that if exact mass measurements are to be used then multiple structurally specific ions should be measured. 

Data from the analyses are collected by a PC running "Mercury MD-1" data analysis software. This software can store multiple calibration curves and raw data finm the samples. The mercury response can be measured using either peak height or integration over time. The PC software is strictly for data acquisition and does not control the instrument start or any operating parameters. 

Figure 16.6 Multiple-wheel electrode half-cell potential measuring instrument with computer-assisted data acquisition. Note the slight wetting of the concrete surface at the wheels in order to achieve a good electrolytic contact between reference electrode and concrete...

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