Method choice

Polymerization inhibitors miscellaneous, 23 383 in styrene manufacture, 23 338 Polymerization initiators alkyllithiums as, 74 251 cerium application, 5 687 peroxydicarbonates as, 74 290 Polymerization kinetics, in PVC polymerization, 25 666-667 Polymerization mechanism, for low density polyethylene, 20 218 Polymerization methods, choice of,... 

Sample size and matrix Your choice of analytical method will also be dependent on the amount of sample you have, especially if the amount is limited and some of the methods under consideration are destructive to the sample. In the Bulging Drum Problem, sample size was not an issue. However, sampling the gas in the drum was challenging, since loss and contamination were quite likely. Getting the samples to the lab presented other challenges. Sample matrix is another important factor in method choice. As you know, some methods and instrumental techniques are not suitable for analysis of solids, without sample preparation. Table 21.8 lists some of the issues that must be considered for different sample matrices. 

Kawai T, Mizunuma K, Yasugi T. 1990. The method choice for the determination of 2,5-hexanedione as an indicator of occupational exposure to -hexane. Int Arch Occup Environ Health 62 403-408. 

Laboratory personnel are as intimately involved in TQM as any other employee and aspects of their work touch on all of these ten points. The manner in which TQM principles specifically apply to laboratory personnel, however, is unique to them. They are concerned about analysis methods, choice of laboratory equipment, error analysis, statistics, acquisition of laboratory samples, etc. 

It is noteworthy that comparisons of existing assessment schemes reveal dissimilarities in the use of extrapolation methods and their input data between different jurisdictions and between prospective and retrospective assessment schemes. This is clearly apparent from, for example, a set of scientific comparisons of 5% hazardous concentration (HC5) values for different substances. Absolute HC5 values and their lower confidence values were different among the different statistical models that can be used to describe a species sensitivity distribution (SSD Wheeler et al. 2002a). As different countries have made different choices in the prescribed modeling by SSDs (regarding data quality, preferred model, etc.), it is clear that different jurisdictions may have different environmental quality criteria for the same substance. Considering the science, the absolute values could be the same in view of the fact that the assessment problem, the available extrapolation methods, and the possible set of input data are (scientifically) similar across jurisdictions. When it is possible, however, to look at the confidence intervals, the numerical differences resulting from different details in method choice become smaller because confidence intervals show overlap. 

Booksh, K.S. and Kowalski, B.R., Calibration method choice by comparison of model basis functions to the theoretical instrument response function, Anal. Chim. Acta, 348, 1-9, 1997. 

Analytical method, choice of, 293 Analytical results, interpretation, 301-305... 

The polyclonal antibodies obtained by immunizing experimental animals have been and will continue to be satisfactory reagents for many immunoassay methods. Choices can be made among adjuvants, routes of injection, dosage and immunization schedules, species of animal to be immunized, etc. (2-6, 28-31). 

The addition of diazomethane to cyclopentene is very slow but it produces 2,3-di-azabicyclo[3.3.0]oct-2-ene in moderate yield (31% in 20 days). Addition of diazoethane is a little quicker and a mixture of endo- and exo-products 12 results which can be separated by preparative GC. Studies of the deazetization of these dienes shows that, as is often the case in the diazabicycloheptene series, sensitized photolysis is the method choice. Regardless of the method of deazetization, there is scrambling and some crossover of stereochemistry in the products. Similar results were reported for the vinyldiazomethane adducts of cyclopentene and cyclopentadiene. ... 

R0yne, F., Penaloza, D., Sandin, G., Svanstrom, M., Berlin, J. Climate impact assessment in life cycle assessments of forest products Implications of method choice for results and decision-making. Journal of Cleaner Production, in press. 

As shown in the table the traffic risk is scaled between 0 to 100 by applying formula (5.2). The normalisation techniques can be tested to show whether the results are highly influenced by any of the methods used in this normalisation. For this empirical sample (11 countries), aU countries did not show any change by using any of the techniques. I prove this by comparing the correlation between each pair of methods as illustrated in Figure 5.2. The correlations are perfect (R-sq=100%) and we can therefore generalise that the results obtained in this study are not influenced by any normalisation method choices. 

Questions frequently arise, especially during the development phase of analytical methods, about how to optimize parameters, such as reaction time, concentration of reagents, etc. and how to optimize analysis procedure, e.g. extraction method, choice of reagent, etc. Questions constantly crop up, e.g. "What effect do pH and EDTA level have on the extraction of a metal ion by means of a chelating agent " - or "What significance do pH and redox potential have in the desorption of heavy metals from sands "... 

TABLE 1-4 Other Characteristics to Be Considered in Method Choice ... 

In Ref [62], the studied object was an epoxy polymer on the basis of resin UP5-181, cured by iso-methyltetrahydrophthalic anhydride in the ratio by mass 1 0.56. Testing specimens were obtained by the hydrostatic extrusion method. The indicated method choice is due to the fact, that high hydrostatic pressure imposition in deformation process prevents the defects formation and growth, resulting to the material failure [64]. The extrusion strain was calculated according to the Eqs. (14.10) and (4.39) and makes up 0.14, 0.25, 0.36, 0.43 and 0.52. The obtained by hydrostatic extrusion specimens were annealed at maximum temperature 353 K during 15 min. 

Translate molecularly based modehng into education, expert systems for method choices (precision in context of time and cost)... 

Bone samples may have bar, flakes, wire or powder form. After physical size, the form of the sample ranks second among the parameters that influence the thermal analysis curves. For most thermal analysis methods, dense powders or small-sized disks are preferred as testing samples. Samples to be analyzed are often cut into thin disks with sizes adapted to the measurement holder. The cutting method choice is also important the avoidance of inducing plastic deformation of the sample is always recommended. 

Depending on the desired materials properties and structure, these approaches have been explored for sol-gel processing of alkoxide-based precursors and further developed in combination with many experimental parameters that can also be adjusted to control the sol composition and particle size, including alkoxide/ water ratio, concentration of the precursors, reaction temperature, reaction time, drying methods, choice and concentration of the catalyst, and the solvent used [42]. Besides the well-known hydrolytic sol-gel processes, even nonhydro-lytic approaches have been reported as a powerful method in the synthesis of mixed oxide materials and will be discussed in more detail subsequently [43]. Another processing option to tailor the material properties is the application of soft or hard templates [44]. In addition to the chemical parameters, drying and thermal treatments or firing processes determine the final architecture, chemical... 

The petroleum analyst is a problem solver and, as such, is constantly required to make method choices. In the past, two questions were most frequently associated with the method selection process. 

Now the analyst is faced with additional complications. These include the need to produce results faster, in more detail, at lower concentration levels to reduce costs (usually in the form of analyst labor) and to provide higher-quality results. In addition, federal and state regulations, particularly on spark-ignition engine fuels, influence method choice. Thus, method choice is now even more difficult. 

---