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Analysis through activation

SCFs are widely used in small-scale laboratory extraction and analysis and are already established for large-scale extraction of caffeine from coffee, flavors from hops, and many other such uses with plant sizes up to 50,000 tons per year throughput. A Philip Morris semicontinuous denicotinization plant is said to employ pressure chambers of 1.5-m diameter and 5-m height. The outlet gas is passed through activated carbon and recycled. ... [Pg.35]

Biblical Studies through Activation Analysis of Ancient Pottery... [Pg.55]

Another case for concurrent validation is that effort that requires statistical (and possibly trend) analysis. It is appropriate to digress and explain what is meant by trend analysis. This activity really consists of product auditing, which is described in more detail elsewhere [32], Product auditing is a QA (management) technique in which each batch s analytical data provide a running score-board of product performance. The quality standards would be measured periodically (monthly, quarterly, or semiannually), which would depend entirely on the number of batches made per time interval. At least six batches would be made in the same manner per chosen time interval. The data would be measured, and then it would be determined (through charting the data) if the data fell between predetermined specification limits. Each new period s data would be... [Pg.811]

After 30 min equilibration at room temperature, the measurement run started. An air flow (room air filtered through active carbon) was conveyed over the sensors at a constant rate (lcm3/s) for 10 s to stabilize the baseline. An automatic syringe then suckled Asiago cheese head-space and conveyed it over the sensor surfaces for 60s. The sensors were exposed again to the reference air flow to eventually recover the baseline. The total cycle time for each measurement was 5 min. No sensor drift was experienced during the measurement period. Each sample was evaluated three times and the average of the results was used for subsequent statistical analysis (principal component analysis (PCA)). [Pg.1085]

The criticisms in the previous paragraphs lead to a question If Hansch analysis is of such questionable value, then why has an entire chapter of this textbook been devoted to the subject Despite the fading utility of classical QSAR methods such as Hansch analysis, the logic behind Hansch analysis is invaluable to medicinal chemistry. Synthetic chemists in the pharmaceutical industry intuitively consider the ideas used to construct Hansch equations. Ideas such as electronics, sterics, and lipophilicity underlie traditional SAR approaches in the laboratory. Critical analysis of activity data and emphasis on seeking holes in R-group selection are also fundamental to successful SAR on a lead. Through the study of Hansch analysis, all these crucial ideas are presented in a rational framework that helps demonstrate their relevance. Just as importantly, Hansch analysis provides the foundation for the next generation of QSAR comparative molecular field analysis. [Pg.315]

The National Committee for Sugar Analysis, through the activities of its subcommittee on color evaluation, has recommended the above definitions of absorbancy and attenuancy. General adoption of these terms by the sugar industry would be a contribution to uniform reporting of their results. [Pg.251]

In this research we have attempted to obtain evidence of the origin of the sherds found in the New World through neutron activation analysis, x-ray diflFraction, and petrographic analysis. Neutron activation analysis provided the concentrations of 15 constituent oxides for 178 sherds. These analyses were carried out in the Chemistry Department at Brook-haven National Laboratory using the standard procedures developed there which are reported by Abascal et al. (3). Six U.S. Geological Survey standard rocks designated AGVl, DTS-1, PCC-1, GSP-1, and G-2 were used as standards (4), The specific standards used for each element are reported by Bieber et al. (5). [Pg.204]

Thermal Desorption Thermal desorption is an alternative GC inlet system particularly used for VOC analysis. However, the analytes subjected to thermal desorption must be thermally stable to achieve successful analysis. Otherwise, decomposition occurs. This technique is mainly used for determination of volatiles in the air. Such a methodology requires sample collection onto sohd sorbents, then desorption of analytes and GC analysis. Traditionally, activated charcoal was used as a sorbent followed by extraction with carbon disulfide. However, solvent desorption involves re-dilution of the VOCs, thus partially negating the enrichment effect. Therefore, the sampling method is to pump a sample of gas (air) through the sorbent tube containing certain sorbents in order to concentrate the VOC. Afterwards, the sample tube is placed in thermal desorber oven and the analytes are released from the sorbent by application of high temperature and a flow of carrier gas. Additionally, desorbed compounds are refocused in a cold trap and then released into the GC column. Such a two-step thermal desorption process provides a narrow chromatographic band at the head of the column. [Pg.410]

Tautomerization is a relatively common feature of drug molecules that is amenable to analysis through the use of chemical shifts or coupling constants as probes. This was recently demonstrated in a study of some nonpeptide endothelin analogs (49). Starting from the modestly active compound (1) (Table... [Pg.526]


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See also in sourсe #XX -- [ Pg.48 ]




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