Experimental comparisons

Here we report only a small selection of experimental results. There are few systematic studies of experimental results of new and conventional techniques for extraction from polymers. Vandenburg et al. [457] have recently compared PFE and MAE with atmospheric pressure methods for extraction of PP/(Irganox 1010, Irganox 1330). 

Vandenburg et al. [92] have also recently published accounts of laboratory methods for the extraction of 

After Vandenburg et al. [457]. From H.J. Vandenburg et al., Analyst, 124, 397-400 (1999). Reproduced by permission of The Royal Society of Chemistry. 

Wieboldt et al. [560] have described SFE-SFC-FTIR analysis of hindered phenol primary antioxidants and phosphite secondary antioxidants in PE. SFE is more selective for the lower-range low-MW polymer than Soxhlet-type extraction. This yields a chromatogram with less interference from low-MW polymer peaks in the region where the additive components elute. As a result, SFE appears to be a better choice than Soxhlet-type extraction for the selective removal of additives from flaked polymer. SFE and dissolution/precipitation methods were compared for a PVC/stabiliser system [366]. 

Kirschner et al. [358] have observed a lower percent finish-on-yarn (FOY) for SFE as compared to solvent extraction of various fibre/textile matrices. This is rationalised as organic solvents tend to extract components from a matrix more vigorously than scCC 2 and thus remove more of the oligomer and organic components present in the fibre. SFE is a potentially softer extraction technique since it removes less of the polymer from the fibre matrix than liquid solvent extraction. 

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Elliott C M, Derr D L, Matyushov D V and Newton M D 1998 Direct experimental comparison of the theories of thermal and optical electron-transfer studies of a mixed-valence dinuclear iron polypyridyl complex J. Am. Chem. 

The acid cleavage of the aryl— silicon bond (desilylation), which provides a measure of the reactivity of the aromatic carbon of the bond, has been applied to 2- and 3-thienyl trimethylsilane, It was found that the 2-isomer reacted only 43.5 times faster than the 3-isomer and 5000 times faster than the phenyl compound at 50,2°C in acetic acid containing aqueous sulfuric acid. The results so far are consistent with the relative reactivities of thiophene upon detritia-tion if a linear free-energy relationship between the substituent effect in detritiation and desilylation is assumed, as the p-methyl group activates about 240 (200-300) times in detritiation with aqueous sulfuric acid and about 18 times in desilylation. A direct experimental comparison of the difference between benzene and thiophene in detritiation has not been carried out, but it may be mentioned that even in 80.7% sulfuric acid, benzene is detritiated about 600 times slower than 2-tritiothiophene. The aforementioned consideration makes it probable that under similar conditions the ratio of the rates of detritiation of thiophene and benzene is larger than in the desilylation. A still larger difference in reactivity between the 2-position of thiophene and benzene has been found for acetoxymercuration which... 

This effect was estimated from the experimental comparison of the stress-strain properties in three sample series which were brought to different phase contents by means of heat treatment. All samples were hydrogen-alloyed to a = 0.35 at T = 1053 K, then furnace cooled. Before straining, samples of the first series were maintained at the test temperature for 0.5 h. Series 2 samples were heated to the j9-phase, T = 1163 K, for 15 min, then cooled to the test temperature and treated like series 1 samples. The phase content in the third series was equilibrated by heating to 1163 K and slow cooling to 903 K before the test temperature was fixed. 

Consider now two solute species Bi and B3, between which no direct experimental comparison by the colorimetric method is possible, because their useful concentration ranges just fail to overlap. We can find an intermediate indicator solute B2, whose useful range partly overlaps that of B, and partly overlaps that of B3. Using B2, a relation between Bi and B3 may thus be established indirectly. In dilute solution this relation will be a simple one. We do not know enough about concentrated solutions to be in a position to say whether a similar relation should be expected. In the experiments to be described, the first aim was to obtain an answer to this question. 

Stevens, G. F., Elliott, D. F., and Wood, R. W., An experimental comparison between forced convection burnout in freon-12 flowing vertically upwards through uniformly and nonuniformly heated round rubes, AEEW-R426, H. M. Stationery Office, London (1965). 

Molecular dynamics (MD) permits the nature of contact formation, indentation, and adhesion to be examined on the nanometer scale. These are computer experiments in which the equations of motion of each constituent particle are considered. The evolution of the system of interacting particles can thus be tracked with high spatial and temporal resolution. As computer speeds increase, so do the number of constituent particles that can be considered within realistic time frames. To enable experimental comparison, many MD simulations take the form of a tip-substrate geometry correspoudiug to scauniug probe methods of iuvestigatiug siugle-asperity coutacts (see Sectiou III.A). 

Normal pH of this sample was 3 2 pH adjusted from 3.2 to 1,1 for experimental comparison,... 

Blundy JD, Dalton JA (2000) Experimental comparison of trace element partitioning between clinopyroxene and melt in carbonate and silicate systems and implications for mantle metasomatism. Contrib Mineral Petrol 139 356-371... 

The above result was used as a ground-stone of the well known kinetic method of detection which was initially proposed by Myasnikov [75] more than 30 years ago. Above paper dealt with experimental comparison of the change of relative concentration of CH3 radicals in gaseous phase using the stationary values of electric conductivity and initial rate of its change. The experiment yielded perfect coincidence of the measured values. Using methyl radicals as example of adsorption it was established that the resolution of this method was better than 10 particles per cubic centimeter of the ambient volume [75, 76]. 

Experimental comparisons may suffer from a lack of optimal conditions for all methods considered or may be based on biased evaluation. It is frequently noticed that results quoted by the preferred extraction technique compare extremely favourably with existing extraction technology. Also, lack of prospects of using CRMs is not helpful for comparisons. However, it appears that for a given infrastructure (R D vs. plant laboratory) and need (routine vs. occasional operations), and depending on the mix of polymeric matrices to be handled, some preferences may clearly be expressed. 

Legon AC (2007) The Interaction of Dihalogens and Hydrogen Halides with Lewis Bases in the Gas Phase An Experimental Comparison of the Halogen Bond and the Hydrogen Bond. 126 17-64... 

Jani, M.A., Toda, K., Takaki, K. el al. (2000) An experimental comparison between electrode shapes for NOx treatment using a dielectric barrier discharge, J. Phys. D Appl. Phys. 33, 3078-82. 

The effectiveness of a combined reduction-biological treatment system for the decolorization of nonbiodegradable textile dyeing wastewater has been investigated. The bench-scale experimental comparison of this technique with other reported combined chemical-biological methods showed higher efficiency and lower cost for the new technique [35]. 

Havens, K.E. 1994. An experimental comparison of the effects of two chemical stressors on a freshwater zooplankton assemblage. Environ. Pollut. 84 245-251. 

N. Delaunay, V. Pichon and M.C. Hennion, Experimental comparison of three monoclonal antibodies for the class-selective immunoextraction of triazines. Correlation with molecular modeling and principal component analysis studies. J. Chromatogr.A 999 (2003) 3-15. 

Wilson-Lingardso, L., Davis, P.W., Ecker, D.J., Hebert, N., Acevedo, O., Sprankle, K., Brennan, T., Schwarcz, L., Freier, S.M., and Wyatt, J.R., Deconvolution of combinatorial libraries for drug discovery experimental comparison of pooling strategies, J. Med. Chem., 1996, 39, 2720-2726. 

Slusarz, K. R., Thompson, M. R., and Christiano, J. P., An Experimental Comparison of the Improved Mixing Obtained from a New Barrier Screw Design, SPE ANTEC Tech. Papers, A7, 262 (2001)... 

The preceding sections have demonstrated that dendrimers of lower generation are akin to branched polymeric structures. It is therefore to be expected that their flow behavior in dilute solution may be described in terms of the well-known concepts of dilute polymer solutions [14, 15]. Hence, dissolved dendrimers should behave like non-draining spheres. From an experimental comparison of and the immobilization of solvent inside the den-drimer can be compared directly since in this case the dendrimer may be approximated by a homogeneous sphere. Therefore R = 3/5 Rl where Ry, denotes the hydrodynamic radius of the dendrimer. This has been found experimentally [19]. 

For future experimental comparisons, we calculated a vibrational frequency shift for the hydrogen molecule moieties of 216cm TZ 2>d f, p) CCSD(T), scaled by 0.95] relative to free hydrogen (Table 13). This frequency corresponds to the asymmetric H-4I stretching mode because the symmetric motion has zero oscillator... 

The overall barrier to ring inversion is well established experimentally, and is believed to correspond to the energy difference between chair and half-chair structures. Less certain are the relative energies of chair and twist-boat conformers and the energy of the boat transition structure, although a small range of values for each of these quantities has been established experimentally. Comparison of the experimental data with the results of calculations is provided in Table 8-5. The... 

Dr. MargerumrAn experimental comparison with the aquo ion was not made in this series because nickel hydroxide would precipitate. However, the Niglycine+ data provides a reference point which suggests all the ku values can be multiplied by a factor of about 10 to give the first-order constant for water dissociation. 

SOURCE J. Vial and A. Jardy, Experimental Comparison of Different Approaches to Estimate LOD and LOQ (fan HPLC Method Anal. Chem. 1999, 71, 2672 and J. M. Green, A Practical Guide to Analytical Method Validation, Anal. Chem. 1996, 68, 305A. 

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