Theoretical plate void volume

Virial coefficients (GC) 5 Viscosity detector (SEC) 452 Viscous fingering (SEC) 447 Visualization techniques (TLC) (see derivatization (TLC)] Void volume, column (LC) 371 measurement 372 Volman trap (GC) 211 Volume of a theoretical plate 49... 

The effective number of theoretical plates is the number of usable theoretical plates and is calculated after elimination of the void volume ... 

Improved separation of natural oil TGs using short columns packed with 3-//m alkyl bonded-phase particles was reported by Dong and DiCesare (88). The HPLC columns used were HS-3 high-speed columns packed with 3-/um C18 bonded-phase particle (100 X 4.6-mm ID) with a column void volume of ca. 0.8 ml and efficiencies in the range of 13,000-15,000 theoretical plates (measured under optimized conditions) and HS5 C,8 columns (125 X 4.6-mm ID packed with 5-yttm particles). Two detectors were used a modified refractive index detector having an 8-/rl flow cell and 0.007-in. ID inlet tubing and a variable-wavelength UV/visible detector. 

The column void volume was slightly less than 0.53 D Morphine was used as standard, retention time 3.5 min. Absorbance of a 10-vl injection of a 1.0 mg/ml solution 0 Number of theoretical plates... 

A diluted solution contains component A, which is required to be isolated by preparative HPLC amongst accompanying impurities. The separation factor of A to the nearest adjacent peak is 1.5 and its retention factor is 4. The analytical column used has a theoretical plate number of 6400 and a void volume of 2 ml. Calculate the maximum allowed injection volume at which peak A actually touches its nearest neighbour. 

The effective plate number corrects theoretical plates for dead (void) volume and hence is a measure of the true number useful of plates in a column ... 

Column effects. In order to establish optimal operating conditions, it is useful to consider the effects of system parameters on the resolution characteristics of an HDC system. HDC has been described as a chromatographic method with very low capacity but very high efiBciency. For example, the calibration curves show that the spectrum of sizes from less than 100 nm to greater than 300 nm is encompassed in less than about 5% of the column void volume. On the other hand, the theoretical plate count corresponding to the marker peak is typically in the range of several thousand per foot. Comparisons in terms of the specific resolution factor, enable a more precise analysis, since both the separation factor and peak dispersion are included in its definition. A simple form for the specific resolution between two particle populations of diameter Dpi and Dp2 is [11]. 

The chromatographic column length L essentially consists of N theoretical plates, on each of which the adsorbent particles are always in equilibrium with the eluent vis-a-vis any solute species. Further, each plate contains V Ncaft of adsorbent, where Vj is the total volume of adsorbent similarly, each plate contains Vm/1V volume of mobile phase, where LeSc = Vm. The distance between two consecutive plates is Le/N, where e is the void volume in the column occupied by the eluent. 

Third, the conditions for scale-up from lab to process plant are constant figures for the dimensionless parameters. But in practice it is not certain that the packing of the columns is always identical. Slight variations of the void fraction and HETP may occur. Additionally, differences in the fluid dynamics, especially at the column inlet and outlet, have to be taken into account. The theoretical scale-up strategy ignores these deviations. But in order to make sure that real numbers of plates of both plants are really the same, it is recommended to determine the Van Deemter plot, void fraction, and friction number for the new packing and to correct the interstitial velocity, the flow rate, and the injection volume. 

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