Packings average pore-diameter

The physical properties of silica are determined by its specific surface area, pore volume, average pore diameter, porosity, and the particle diameter and shape [8]. The latter two are responsible for the efficiency, the physical stability and the pressure drop of the packed columns and do not contribute to retention and selectivity. 

In porous packing materials with 10-nm average pore diameter, 99% of the available surface area is inside the pores. Conversion of highly polar silica with high sUanol density (4.8 groups/nm ) [7] into the hydrophobic surface requires dense bonding of relatively thick organic layer which can effectively shield the surface of base silica material. 

Multipoint BET analysis showed that the surface area and average pore diameter of quartz are about two times higher than that of dolomite. These results are important especially in the random packing on the filtration and the compaction behavior of the cakes in shear strength measurements. 

Figure 9 Elution profiles for sperm whale myoglobin (SWMYO) chromatographed on Bakerbond C g and C4 sorbents, monitored at 215 and 400 nm. The mobile phase consisted of a linear 60 min gradient of 0.1% trifluoroacetic acid-H2O to 90% acetonitrile-H20 containing 0.1% trifluoroacetic add (buffer B), at a flow rate of 1 mL/min. In this study, the SPMYO sample was chromatographed on the C,g and C4 sorbents (nominal 5 pm particle size and 30 nm average pore diameter) pack into columns of dimensions of 250 x 4.6 mm ID. at 25 C. On-line photodiode array detection (DAD) was achieved using an LKB 21440 Rapid Spectral Detector, and the spectra were analyzed using the Wavescan software. The later eluting peak, with absorption at 400 nm, corresponds to the heme moiety. (Data from Ref. 106.)...

The gel-filtration medium is normally packed into a stainless steel column characterized by an i.d. between 4 and 25 mm and a length between 300 and 600 mm. Four important factors in characterizing SEC packings are the average particle size, the particle size distribution, the average pore diameter, and the pore size distribution. The particle size and the particle size distribution have a significant influence on the column efficiency, which is most decisive in SEC, because the biopolymers are eluted isocraticaUy in a small elution window with... 

Stickler s Equation—In Chapter 6 we have given a rather extensive account of Slichter s (1899) analysis of the packing of spheres, and we discussed the average pore-area in a unit-cell and the mean length of path. The former was expressed in terms of the diameter of the spheres,... 

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