Chromatography bandwidth

Stewart, J. E., Spectral-bandwidth effects of variable-wavelength absorption detectors in liquid chromatography, ]. Chromatogr., 174, 283, 1979. 

However, the calculation requires different algorithms for each specific case. Hence, an explicit mathematical solution providing basing retention data (elution volumes or times, bandwidths, and resolution) is much more frequently used in analytical gradient chromatography, even at a cost of some simplifications [9-11]. 

Combining Equations 5.8 and 5.5, we obtain Equation 5.9 allowing prediction of bandwidths in RP gradient chromatography ... 

Lor a particular analytical separation, each biosolute will have an optimal k] value for maximum resolution with a designated column, flow rate, and mobile phase composition. Similar criteria apply in preparative (overload) chromatography with multicomponent mixtures, where resolution is similarly enhanced following optimization of chromatographic selectivity and zone bandwidth. The conventional approach to process purification with low molecular weight solutes has frequently been based on linear scale-up of the performance of an analytical column system. In these cases, high-resolution separations can be achieved often without the burden of conformational or... 

The efficiency of separation in all types of column chromatography depends on the extent to which the sample bandwidth broadens during development of the chromatogram. Three factors determine this broadening (1) axial diffusion of solutes within the mobile phase, which is... 

Jandera, P. Churacek, J. Gradient elution in liquid chromatography II. Retention characteristics (retention volume, bandwidth, resolution, plate number) in solvent-programmed chromatography—Theoretical considerations. J. Chromatogr. 1974, 91, 223-235. 

Figure 6-6 Schematic diagram of a chromatogram obtained from a column and open-bed chromatograph (planar). In open-bed chromatography (bottom), strongly retained compounds (B) move more slowly than less strongly retained compounds. In column chromatography (top), compound B is eluted later than compound A, again because of stronger retention, Rj, Resolution Vr A), retention volume for solute A V,(B), retention volume for solute B w A), bandwidth (units of volume) measured at base for solute A w(B), bandwidth (units of volume) measured at base for solute B V , volume between Injector and detectors d(A), distance traveled by solute A A, solute A B, solute B.

The apparent plate munber can be calculated from the experimental profiles [27]. However, this number depends on the fractional height at which the bandwidth is measured. The value of Nth is calculated from the profiles predicted, under the same experimental conditions, by the ideal model. Finally, Nion is derived from the band profiles recorded in linear chromatography, e.g., with a very small sample size, using the relationships valid for Gaussian profiles. From Eqs. 7.24 and 7.26, we can derive the band width at half height, Wi/2, and the retention time of the band profile, ty, obtained with an infinitely efficient column. In the case of a Langmuir isotherm, we obtain [31]... 

Numerical calculations involving the Error curve are certainly made very easy by means of the spreadsheet. This applies not only to statistical considerations, but to simulation of chromatograms as well. Explanation of band shapes is elucidated by attributing their characteristics to those of the Gaussian curve. Thus, bandwidth is related to a, the standard deviation, V., the retention volume to p, the mean, as is well known in contemporary discussion of chromatography. Similarly, one can... 

Cryogenic traps are convenient accumulation and injection devices for fast gas chromatography and interfaces for coupled-column gas chromatography, where a heartcut sample is collected and focused from the first column, and reinjected into the second column. The main requirement for a cryogenic trap used in these applications is efficient accumulation over time with rapid injection of the collected analytes as a narrow pulse in both time and space. Commercially available systems using a capacitance discharge for heating provide injection bandwidths of 5-20 ms. 

Gritti, F. Guiochon, G. The bandwidth in gradient elution chromatography with a retained organic modifier. J. Chromatogr. A, 2007,1145, 67-82. 

Nomenclature from distillation carried over to chromatography. We speak of a chromatography column as if it were divided into discrete sections (called theoretical plates) in which a solute molecule equilibrates between the mobile and stationary phases. Retention of a compound on a column can be described by the number of theoretical equilibration steps between injection and elution. The more equilibration steps (the more theoretical plates), the narrower the bandwidth when the compound emerges. 

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