Capillary characteristics

Measurements very sensitive to solution composition, dissolved oxygen and capillary characteristics. Impurities in background electrolyte limit sensitivity. 

Amperometric titrations are inherently more precise than polarography and are more generally applicable because the analyte need not itself be electroactive. Titrations involving the DME are not affected by changes in capillary characteristics as are conventional polarographic determinations, whilst working at a predetermined temperature is unnecessary provided that it remains reasonably constant throughout the titration. 

Our description of the DME starts with a discussion of basic concepts involved in the formation of mercury drops. These considerations are subsequently used to define the capillary characteristics required for satisfactory elec-... 

The ratio of the wave height of the unknown to that of the pilot can be assumed to be independent of capillary characteristics, viscosity of the solution, temperature, etc. Hence, a new measurement of this ratio is not needed whenever the capillary is replaced, and the temperature need not be controlled. The calibration curves are constructed by plotting the ratio of the heights of the two waves against the concentration of the substance to be determined, keeping the concentration of the pilot species constant. Such calibration curves can be used for evaluation of sample solutions (to which the same concentration of the pilot substance has been added) in the same way as the simple calibration curves mentioned above. 

The diffusion current constant Ja is used to correct polarographic diffusion currents for differences in capillary characteristics. For average currents... 

For a given electroactive substance under a given set of experimental conditions (temperature, supporting electrolyte, potential of the DME, etc.), should actually be a constant according to the Ilkovic equation it should be independent of the capillary characteristics and reproducible in different laboratories or in the same laboratory with different capillaries. Cadmium ion exhibits a reversible two-electron reduction wave at -0.64 V in 1 M HCl. A 0.50 mM Cd + solution gave a wave with average id = 3.96 fiA at the En the capillary characteristics were m = 2.50 mg/sec, t = 3.02 sec. (a) Calculate h for Cd +. (b) Calculate the diffusion coefficient for Cd in 1 M HCl. 

Surface Coating and Separation Matrix 16.2.2.1 Capillary Characteristics and EOF Suppression... 

The performed analysis shows that the system behaviour varies significantly depending on the experimental conditions. The most important factors are the type of cell (open or closed), the cell volume and the walls rigidity, the capillary characteristics and the equilibrium meniscus height. By appropriate choice of the experimental conditions one ean vary the main system parameters, such as characteristic frequency, meniscus frequency in the open cell or damping coefficient, and in this way control the system response. For a quantitative description of the dynamic behaviour of the system one should determine exactly all the system parameters. In practice, this problem can be solved via special calibration experiments. 

These equations were solved utilizing a finite difference technique similar to that developed by Appeldoorn and co-workers (15,22,23). The major difference between this analysis and that presented by Appeldoorn is that in this study the inertial terms are included in the axial momentum equation since the Reynolds numbers of the flow fields considered in this study are significantly higher than those analyzed by Appeldoorn and co-workers. In conclusion, the pressure drop required for a given volumetric flow rate for laminar flow in a capillary at high-shear rates can be theoretically determined if the capillary characteristics and the appropriate physical properties of the fluid are known. As indicated in the above boundary conditions, two oases concerning the thermal conditions at the... 

Fig. 3 Comparison of theoretical calculations with capillary viscometer data for a Newtonian oil at 37.6 C. Capillary characteristics ...

The lower viscosity adhesives (2-20 mPa-s) are often used where the adhesive needs to be post-applied as these products will tend to have good wicking and capillary characteristics. 

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