Other practical considerations

Before attempting to make electrode measurements, it is necessary to test the instrumentation that is to be used. It is very useful to do this by making measurements on a known system. In view of all the data that are now available for the protonation of diphenylethylene anion radical in DMF by methanol, this should be a good standard system [55—57]. 

Calibration of the linear sweep voltammetry measurement procedure on a reversible electrode process  

The kinetic zone most suitable for heterogeneous charge transfer studies is the QR zone (Fig. 4). Studies are also possible in the IR zone, but these are less productive since there is no reverse peak during CV and it is necessary to know Eiev, which is usually not available for irreversible processes, in order to apply LSV studies. Theoretical relationships for CV and LSV will be presented in the following sections and some practical examples are presented later. 

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In addition to the cost-benefit aspects of appraisal activities, there are frequently other practical considerations which affect appraisal planning, such as... 

Discussed below are various modes of separations in HPLC. Included here is brief coverage of mobile-phase selection for various modes of chromatography and elementary information on mechanism, choice of solvents and columns, and other practical considerations. It should come as no surprise that reversed-phase HPLC is discussed at greater length in this section because it is the most commonly used technique in HPLC (more detailed discussion is provided in Section 15.8). Clearly,... 

Other Practical Considerations. FILTRATION. Filtration of the sample is important to separate the dissolved compounds of interest from suspended organic carbon from biological organisms such as bacteria, algae, and microcrustaceans and from clay minerals, all of which could interfere with subsequent analyses. Filtration through a 0.45-/xm or smaller filter is the accepted practice, but this step can become prohibitive both in time and expense in a procedure of this magnitude. 

The size of the adsorbent beds is limited by factors such as the physical strength of the adsorbent materials, vessel transportation, efficiency of flow distribution and other practical considerations. As a result of recovery and bed size limitations, the production rate of 2.-, 3-, or 4-bed systems generally has an upper limit of 12-13 MMSCFD. 

When faced with a choice between two assays you may compare either their SDs, or their standard errors for any fixed n, to determine which assay is most useful. The more precise assay is generally preferred if biases are similar, assuming costs and other practical considerations are comparable as well. In such circumstances, an assay with SD = v = 0.09 is much preferable to one with r = 0.36 similarly, a triplicate assay procedure with SE = 0.02 is greatly preferable to another triplicate procedure with SE = 0.07. 

Some authorities favor carrying roll crushing down to H 5 of an in. but the limit for these machines is today owing to other practical considerations about K in. At one time there was and there is still an active school which advocates taking material directly from large crushers and feeding it to ball mills for reduction to sand sizes. This practice led to some disastrous deficiencies in expected tonnages. The tendency today is to consider material 1 in. in size and smaller as the maximum in point of size which should be fed to ball mills. As to whether coarser material can be fed with satisfactory capacities will depend upon its hardness. 

With such a system, one must slowly develop the chromatographic distribution pattern through the different zones. It may take from 8 to 36 hours for the pattern to be established. Other practical considerations are that the recirculation system must represent a small (< 10%) portion of a single... 

Other practical considerations are attrition of particles caking of catalyst from malfunctioning of the reactor due to formation of tarry products (resulting sometimes in cakes as large as the reactor diameter) and the need to avoid premixing of reactants (particularly when they can form explosive mixtures) and fix their relative locations within the bed (e.g., in the chlorination of methane and ammoxidation of propylene). Refer to Doraiswamy and Sharma (1984) for further details. 

A general list of coat function and release mechanisms commonly employed is provided in Table 7.8. In addition to coat material concerns noted in the previous section on coating ingredients, there are other practical considerations that should be taken into account when formulating. 

The lower enantioselectivity achieved by phosphine sulfides and other practical considerations (like product crystallinity or ease of purification) have made phosphine boranes the reagents of choice in enantioselective deprotonation. Recently, however, it has been showed that in certain cases phosphine sulfides outperform the borane counterparts. O Brien and co-workers developed a strategy to prepare both enantiomers of phosphine derivatives using enantioselective deprotonation with (-)-sparteine (Scheme 5.44). 

Material may be deemed to be unsuitable for reticle because of the associated radiation doses, difficulty in conducting verification surveys, decontamination cost, economic worth, or other practical considerations. In these circumstances, the material may be recycled under controlled conditions, or sent for disposal to normal landfills or to controlled sites as low level radioactive wastes. 

An option that may be considered in some situations is the controlled use of equipment, parts, tools, or even basic metals. In this option, the material in question may not meet the appropriate criteria for unconditional release, but because of economic or other practical considerations, recycle or reuse may be prescribed for a limited (controlled) pxupose. Such materials may be recycled within the nuclear industry if controls can ensure that the radiation exposure of workers within the nuclear industry can be kept to acceptable levels. An example is the potential recycle of contaminated steel for use as canisters for waste disposal. 

Other practical considerations Washing the microsyringe several times with the solvent used in SDME is recommended to remove the air. Elat-bottom vials allow a set location for the stir bar, so that the water flow pattern is quite similar. 

Noise, Detection Limits, and Linearity Other Practical Considerations... 

The optimum choice of a steel for a particular application should be made in the light of expressions such as Eq. (5.2), which reflects the corrosivity of the environment as a function of the metallurgical composition and structure. But other practical considerations such as availability of the materials, maintainability, and economical requirements inevitably dictate the use of an alloy out of its safe envelope, in which case the application of coatings, cathodic protection, and/or some other protection scheme, appropriate for the operating conditions, have to be considered. Another important consideration is the accidental damage that can locally modify the pattern of stresses imposed on a metallic component or can destroy some of the protective barriers. 

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