Control peak resolution

The previously discus.sed thermodynamically controlled molecular recognition processes are the basis for a successful enantioseparation. However, from a separation methodological point of view, also the performance of the separation system has to be considered, which in addition to the thermodynamically controlled enantioselectivity determines the peak resolution () which is a measure for the quality of a separation. 

Capillary-column dimensions and the average carrier-gas linear velocity exert a strong influence on peak resolution and the speed of analysis. Chromatogra-phers can control a separation s characteristics by choosing these parameters as required to meet specific performance goals. In order to simplify the discussion and to provide a clear separation of the variables inflnences, we will hold the column temperature constant when considering the effects of changing the physical column parameters. The influence of colunm temperature is addressed later in this chapter. 

In summary, the ATP example shown here describes critical method performance requirements, that is, those characteristics that have a direct impact on the ability of a method to quantitate an analyte. LC-method attributes such as peak resolution, linearity, and efficiency, are not included. Although they are important features of an LC method and should be evaluated and incorporated into the control strategy as required, they do not provide a direct measiu-ement of the ability of a method to accurately quantitate an analyte and should not appear in the ATP. 

The nozzle rapidly evaporates the mobile phase while depositing a tightly focused track of the solute. When a chromatogram has been collected on the sample collector disc, the disc is transferred to the optics module in the FTIR instrument for analysis of the deposited sample track. A control module defines the sample collection disc position and rotation rate in order to be compatible with the run time and peak resolution of the chromatographic separation. The sample collection disc is made from germanium which is optically transparent in the range 6,000 50 cm The lower surface of the disc is covered with a reflecting aluminium layer [115]. 

The number of discrete points of /cicc( ) determines the resolution of the chirality code is a smoothing factor which in practice controls the width of the peaks obtained by a graphical representation versus u. An example of a chir-... 

To reiterate the definition of chromatographic resolution a separation is achieved in a chromatographic system by moving the peaks apart and by constraining the peak dispersion so that the individual peaks can be eluted discretely. Thus, even if the column succeeds in meeting this criterion, the separation can still be destroyed if the peaks are dispersed in parts of the apparatus other than the column. It follows that extra-column dispersion must be controlled and minimized to ensure that the full performance of the column is realized. 

The two types of overload have quite different effects on the separation process, i.e., the resolution that is obtained from the column and the shape of the resulting peaks. Both sampling techniques can be very effective, but need to be carefully controlled and the procedure well understood if sample purity is to be maintained. 

According to Equation 3, the resolution of two peaks in column separation is controlled by three major variables retention defined in terms of the retention factor k column efficiency expressed as the number of theoretical plates N and selectivity characterized by the selectivity factor a [48] ... 

Analytical Techniques. Sessile drop contact angles were measured with a NRL C.A. Goniometer (Rame -Hart, Inc.) using triply distilled water. The contact angles reported are averages of 2-8 identically treated samples with at least three measurements taken on each sample. ESCA spectra were obtained on a Kratos ES-300 X-ray Photoelectron Spectrometer under the control of a DS-300 Data System. Peak area measurements and band resolutions were performed with a DuPont 310 Curve Resolver. 

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