Continuous Monitoring Approach

A second approach to gravimetry is to thermally or chemically decompose a solid sample. The volatile products of the decomposition reaction may be trapped and weighed to provide quantitative information. Alternatively, the residue remaining when decomposition is complete may be weighed. In thermogravimetry, which is one form of volatilization gravimetry, the sample s mass is continuously monitored while the applied temperature is slowly increased. 

Infrared (IR) investigations can be made on a sample of reactant previously heated to a known extent of reaction (a) and studied in the form of a mull or in an alkali halide disc. An alternative approach is to incorporate the reactant substance in a compact alkali halide disc [287] which is intermittently withdrawn from the reaction vessel for infrared measurements at appropriate intervals. Heated sample holders [288,289] permit repetitive scanning of the spectrum or continuous monitoring of a peak of interest during decomposition. 

From the above, derives the fundamental concept that the newborn infant must be maintained in an adequate degree of hydration and in electrolyte balance in order for the infant to thrive. In some cases, where for one reason or other, the infant is not able to take fluids by mouth in the normal manner, one may need to resort to supplementary fluid therapy by vein. For a rational approach to this problem one needs to have available from the clinical chemical laboratory> rapid response in order to continuously monitor changes in electrolyte levels so that fluids can be modified so as to correct these abnormal-ities. 

A patient with acute pancreatitis may develop many severe local and systemic complications. Local complications involve fluid collection, necrosis, or abscess in the pancreas. A pancreatic fluid collection (or pancreatic pseudocyst) is a collection of tissue, pancreatic enzymes, and blood that forms weeks after acute pancreatitis. Many pancreatic pseudocysts resolve spontaneously, but some require surgical drainage.5 Rupture of a pancreatic pseudocyst with associated erosion and hemorrhage of major abdominal blood vessels can have a mortality approaching 60% thus, continued monitoring of a pseudocyst is prudent.6... 

As the maturity of the process increases, only these key parameters would require continued monitoring. Ultimately, the data collected on these properties would permit the generation of appropriate material specifications. If the work had been performed properly, then it would be possible to specify limits for raw-material properties that would ensure the final product will be satisfactory. These guidelines would naturally apply only to the specific formulation, but through continued use of the systematic Materials Science approach the more general trends would become apparent. 

Lan and Mottola [14] have presented two continuous-flow-sensing strategies for the determination of C02 in gas mixtures using a special reaction cell. Both approaches are based on the effect of the complex of Co(II) with phthalocyanine as a rate modifier of the CL emission generated by luminol in the absence of an added oxidant agent, which is enhanced by the presence of C02 in the system. This enhancement allows the fast and simple determination of carbon dioxide at ppm levels (v/v) in atmospheric air and in human breath. In the first case, a continuous monitoring system was applied however, because the flow of expired gas is not constant, a discrete sample introduction approach was used in the analysis of C02 in breath. 

Polarographic probes that respond specifically to concentrations of Oj, CO2 or SOj are very useful. They have decided advantages over the more clumsy manometric monitoring. Their use is limited to slow reactions or the continuous-flow approach, because of the relatively long response time of the probe. An 02-eleetrode system for incorporation in a spectrophotometer cuvette, for simultaneous monitoring of [Oj] and spectral changes, has been deseribed. 

Major categories of process Raman applications include reaction monitoring, in-process quality checks, and mobile or field point measurements. Quality control laboratory applications often are converted to a continuous process monitoring approach, or could simply be viewed as part of a larger production process. 

Continuous monitoring of organ function displays in real-time the clearance profile or concentration of an organ function-specific marker in a pre-deter-mined body compartment. This approach allows the early intervention by clinicians since instantaneous deviation from the established baseline reading may indicate the onset of an anomaly. However, it may not be useful for measuring dynamic functional reserve of the organ because subsequent activities after marker elimination from plasma may not be reflected in the clearance profile. 

One approach which does not utilize a confining fluid has been developed by Saylak (83). This technique involves an optical system which continuously monitors the lateral strain in a uniaxial specimen. The specimen must be circular in cross section, and the volume change computation requires uniform dewetting throughout the sample. This method is not rate and temperature limited since no mechanical attachments or fluids are in contact with the sample. A schematic of the lateral strain device is shown in Figure 13. Surland and Givan (104) also describe an... 

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