Peaks width, optimizing

Rather than the separation function, resolution between individual peak pairs is used in most automated optimization procedures because it is easier to calculate, although non-Gaussian pe2dcs and overlapping peaks can present problems due to the difficulty of estimating peak widths. A simple objective function would be to consider only the separation between the worst separated peak pair, ignoring all others. If a set of... 

These parameters are determined by non-linear least-squares optimization of the fit of the function to both the experimental storage and loss moduli curves. As emphasized, the two determiners of temperature-scan peak width referred to above (i.e., in terms of equation (2), activation energy AH of x0 and a ) have features that allow distinguishing... 

Total theoretical peak capacity for the ID and 2D LC/MS analyses of the yeast ribosomal protein sample was calculated as 240 and 700, respectively. Individual separation peak capacities were calculated by dividing the total separation time by the average peak width at baseline, and the 2D peak capacity determined as the product of the peak capacity of the two dimensions. These theoretical calculations rely on optimal use of the two-dimensional separation space, which in turn is dependent upon the lack of correlation between the component retention times in the two separation modes. Thus, the maximum use of the theoretical peak capacity is not only dependent on the selection of chromatographic modes based on different physicochemical... 

If the LC part is optimized to deliver peaks in a shorter time or more peaks in the same time when compared to a conventional method, we must consider the system s ability to handle data. Because the speed optimization described above will produce much narrower peaks, widths below 1 sec can be achieved easily. However, the data acquisition rate and data filtering steps must be considered. 

One reason for lower sensitivity is the lack of flexibility to optimize the positions of the sprayers on the MUX interface another may be the lower electrospray desolvation efficiency on the MUX. The longer total cycle time on a MUX interface with a quadrupole MS in comparison to a single sprayer interface adds another concern. Assuming typical chromatographic peak widths appeared on average at 15 sec, 17 data points could be easily detected across the peak for each transition with a total cycle time of 0.88 sec on a conventional single sprayer set-up. With the MUX, only 12 data points could be detected across the same peak even with a total cycle time of 1.24 sec because of the introduction of additional interspray time on top of dwell time. Hence, when MUX is used with a quadrupole mass analyzer, it is important to consider dwell time and chromatographic peak width... 

Injection voltage is varied between +500 and + 2000 V and maintained for 5, 10, and 20 s. Separation is carried out by applying a voltage of +2000 V using a detection potential of +0.7 V and 50 mM Tris-based buffer pH 9.0. Choose optimal injection time/voltage taking into account of peak current (7P) and half-peak width (1U1/2). 

Optimal detection potential, separation voltage, and injection time/ voltage are used to determine parameters such as electroosmotic velocity (ueo = Leff/tm) and mobility (/[Pg.1282]

The important aspect of programmed elution techniques with respect to optimization criteria is that the peak width does not increase with the retention time in a manner corresponding to eqn.(1.16). In programmed analysis a constant peak width is wanted throughout the chromatogram (see section 6.1). 

Toon and Rowland [557] used a similar method for the optimization of the composition of a binary mobile phase in RPLC. However, they did not use eqns.(5.16) and (5.17), but plotted lines for the observed front and back of the peak. Since these quantities are affected not only by the capacity factor and the peak width of the solute, but also by the sensitivity of the detection, the method of Colin et al. is to be preferred. 

As shown by Eq. (1), the resolution of components in a liquid chromatographic separation is dependent on (1) their relative retention on a particular chromatographic system and (2) their peak widths. To optimize these parameters for maximum resolution, a clear understanding of their nature and the factors that affect them is necessary. Although the retention time of a component adequately describes the amount of time a particular solute takes to elute from a chromatographic system, a more useful parameter describ-... 

Finally, it must be said that in most of the practical cases, retention ratio and peak width are satisfactorily predicted by the 2D models. The role of the 3D models was to estimate the contributions of the 3D effects and to determine the optimal conditions when these... 

DST methods are particularly competitive for organic compounds, which are more resistant to the traditional approaches and whose structural models can be easily guessed. At present, the complexity of crystal structures solved by direct-space methods is essentially limited by the number of DOFs that can be handled by the global optimization algorithms within a reasonable amount of time. In prospect, improvement of both search algorithms and computer power may overcome this limitation. The major pitfalls for the use of DST are (a) they are time consuming (b) they are dependent on the existence of reliable prior structural information. Partially incorrect models may compromise the success of the procedure independent of the computer time spent (c) they are sensitive to the accuracy of the peak profile parameterization through peak-shape and peak-width functions. ... 

ED (BGE optimization). Three-level full factorial design. Factors pH, sodium octanesuHonate concentration. Response migration time, peak width, resolntion. 

Injection effects may be minimized by dissolving the sample in a weak solvent however, even in the absence of injection solvent effects, the volume of injection should be optimized depending on the goals and objectives of the assay. Bristow (10) recommends an injection volume less than one-tenth of the peak volume to maintain resolution and injection volume up to one-fourth of the peak volume if sensitivity concerns override resolution concerns. The peak volume is the volume of mobile phase that contains the peak at the detector (product of flow rate in volume per minute and peak width in minutes). If the solute s retention is increased, the peak is broadened, then the injection volume may be increased (10). This is consistant with the model developed by Ng and Ng (4). 

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