Capacity factor correction term

Once the appropriate detector is chosen and the hardware system is operating correctly, the next ingredient for a successful chromatogram is retention of the components in the mixture. The measure of the retention of a compound on a column is referred to as the capacity factor and is a measure of retardation of the compound in terms of the number of column void volumes it takes to elute the apex (center) of the peak. This measure is called k (pronounced kay prime) and is simply the ratio of the elution volume of the component (V/) to the void volume of the column (Vo), which is expressed as... 

Retention factor, k lUPAC 1993 term for capacity factor. Capacity of a stationary phase to retain a component, measured as the ratio of corrected retention time (Ir) and column dead time (/m),... 

The overall calorimeter equation of the Calvet calorimeter is finally given by Eq. (4). The overall heat effect, AH, is equal to the time integral over the Peltier compensation, the major effect to be measured, corrected for two factors the time-integral over the just-discussed losses, 4>, and, if the temperature does not stay exactly constant during the experiment, a correction term which involves the heat capacity of the calorimeter and the sample, C. All three terms can be evaluated by the measurement of the Peltier current i, the measurement of the emf of the measuring thermocouples, and a measurement of the change of the emf with time. The last term is needed for the calculation of the heat capacity correction which is written in Eq. (4). The last two terms in Eq. (4) are relatively small as long as the operation is close to isothermal. 

The BCFs obtained for 13 phenols ranged from 1.4 for DNOC to 980 for PCP BCFs as well as concentrations of phenols in water (Cy ), partition coefficients (P), a term correcting for the degree of dissociation of phenols with respect to a certain pH of the test water (log(10P P +1)), and an indicator parameter representing the Structure element 2,4-dinitro-substitution (IN) are compiled in TABLE 3. Log P values listed in TABLE 3 were calculated from capacity factors (log k°) on the basis of the regression equation reported earlier (Butte et al. 1981) ... 

The Ft correction factor is usually correlated in terms of two dimensionless ratios, the ratio of the two heat capacity flow rates R and the thermal effectiveness P of the exchanger ... 

For example, Marshall and Slusher (1966) made a detailed evaluation of the solubility of ealeium sulphate in aqueous sodium chloride solution, and suggested that variations in the ion solubility product could be described, for ionic strengths up to around 2 M at temperatures from 0 to 100 °C, by adding another term in an extended Debye Hiickel expression. Above 2 M and below 25 °C, however, further correction factors had to be applied, the abnormal behaviour being attributed to an increase in the complexity of the structure of water under these circumstances. Enthalpies and entropies of solution and specific heat capacity were also reported as functions of ionic strength and temperature. 

The cost of electric power was estimated as the sum of four terms. The first is the cost to provide the steam flow (in pph) noted in Table 4.11. That value was converted to a requirement for energy as 945 BTU/lb steam, and the conversion factor of 3415 BTU/kilowatt (kW). The second term was the power cost to continually operate the air amplifier, taken to be a 6 HP motor. The third term was the power cost to operate a 3 HP water pump for condensed water and solvent vapor fed to the decanter. The fourth term is a general allocation of 52 kW for miscellaneous and unspecified needs. This value was taken from the reference of Appendix A2, Footnote 12, page 34. Both the third and fourth terms were corrected for the actual capacity of activated carbon using the six-tenth power rule used to estimate capital investment. The sum has the units of kW hours. 

The first term in Eq. (14) is only the approximate heat capacity in a differential thermal analysis experiment. It is derived already in part in Fig. 4.16 as the steady-state difference between block and sample temperatures. The second term is made up of two factors. The factor in the first set of parentheses represents (close to) the overall sample and sample holder heat capacity. The factor in the second set of parentheses contains a correction factor accounting for the different heating rates of reference and sample. For steady-state a horizontal base line is expected, or dAT/dTj. = 0 the heat capacity of the sample is simply represented by the first term, as suggested in Fig. 4.16. When, however, AT is not constant, the first term must be corrected by the second. 

---