Separative capacity three-component

As was reported by Soczewinski, a three-component mixture containing 5 mg of each of the ingredients can be completely separated using a 90 X 100 X 0.5 mm layer of silica [26]. This indicates that the capacity of the chromatographic system can be considerably increased by the apphcation of wider and thicker layers of adsorbent on the chromatoplate [44]. 

Xanthines. It was found that the capacity factors and the separation ratios were both functions of the identity of the modifier as well as of the quantity of the modifier in the carbon dioxide. In Figure 6, it can be seen that with 9-5% 2-methoxyethanol in carbon dioxide the first two components of a xanthine mixture, caffeine and theophylline, are not well-separated but the elution order is caffeine, theophylline, theobromine, and xanthine. At 6.5f 2-methoxyethanol in carbon dioxide, there is essentially baseline resolution of the first three components in less than one minute xanthine (not very soluble in liquid 2-methoxyethanol and not at the usual 1 mg/mL sample concentration but at some undetermined saturation concentration) at a k of over 5 has begun to tail and to disappear into the baseline. While it is obvious that the capacity factors, k, increase with a decrease in modifier concentration from 9-5 to 6.5% 2-methoxyethanol in C02, less obviously the separation ratios (for example, with respect to caf-... 

The effect of the modifier identity can be seen in Figure 7 which shows the separation of the xanthines with 9.5% 2-propanol in carbon dioxide. Compared to 9.5% 2-methoxyethanol, the capacity factors of the first three components are significantly larger (by a factor of 1.6 to 2.5) the elution order is also... 

Figure 3.67a-c shows the single chromatograms of a three-component mixture on three different stationary phases a highly unpolar RP-18e phase, a combined reversed phase/weak anion exchange phase (RP/WAX), and a cyano-modified phase. All three stationary phases have been prepared on the same base silica, a 12 pm, 100 A LiChrospher . While on the RP-18e-phase the mixture can be separated, the retention on the other two phases is shorter and insufficient for complete resolution. Through the combination of the different stationary phases the retention time of a single run with sufficient resolution can be reduced from 5 to 3 min which is equivalent to a capacity increase of the system of 40%. This can be achieved by a selection of RP-18e and RP/WAX-phases in a 2 3-combination (Figure 3.67d) (Horn, 2004).

Factors Which Influence Resolution. In order to effectively apply SMGPC to separation problems, the influence of three factors on the resolution of sample components must be considered. Solvent effects play a minor role, but choice of eluent can alter selectivity in some cases. Column efficiency, as noted, has a major impact on the quality of separation. The number of peaks which can be resolved within the pore volume of a given column (i.e. peak capacity) is related to the square root of the number of theoretical plates (13). Finally, the nature of the calibration curve will influence resolution. Each... 

Once the design equations were developed and ap proved, the constant-level skim tank was put together quickly as a result of its simplicity and the availability of component parts. No moving parts are involved, and corrosion resistance was built in, giving it the reliability that was sought. Initial outlay was less than the price of a freewater knockout with comparable capacity. In addition. operating expenses are nil. I hus. this separator met the three secondary design criteria. 

Preparative-scale chromatography relies on a compromise between three variables (cf. Figure 1) (i) component resolution (determined by selectivity, efficiency and retention factor), (ii) speed of analysis and (iii) column sample capacity (Pescar, 1971). Any two of the desired goals may be realized only at the expense of the third. If a large amount of sample is required in a short time, resolution must be high. If resolution is insufficient, either the column load is limited or the time required for separation is long. 

Lithion s low rate 7Ah cells. The cells were fabricated with Setella E20 separator, 1M LiPF6 in EC DMC DEC (1 1 1) electrolyte and standard cathode components. The charge capacity of each cell is designated at 9 Ah during the C/20 formation cycle. This value is based on a cathode specific capacity of 190 mAh/g at the C/20 rate. The 8 Ah designation for each cell during the initial two C/10 charge cycles is based on a specific cathode capacity value of 170 mAh/g. After a preliminary evaluation of the three formation cycles, the cells were sealed and cycled for additional 7 cycles to stabilize data for the C/10 rate. A 72 h stand test was performed on cells after completion of the ten formation cycles. 

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