Efficiency chromatographic column

Column Efficiency. Under ideal conditions the profile of a solute band resembles that given by a Gaussian distribution curve (Fig. 11.1). The efficiency of a chromatographic system is expressed by the effective plate number defined from the chromatogram of a single band. 

Two methods for improving chromatographic resolution (a) Original separation showing a pair of poorly resolved solutes (b) Improvement in resolution due to an increase in column efficiency ... 

In their original theoretical model of chromatography, Martin and Synge treated the chromatographic column as though it consists of discrete sections at which partitioning of the solute between the stationary and mobile phases occurs. They called each section a theoretical plate and defined column efficiency in terms of the number of theoretical plates, N, or the height of a theoretical plate, H where... 

Now that we have defined capacity factor, selectivity, and column efficiency we consider their relationship to chromatographic resolution. Since we are only interested in the resolution between solutes eluting with similar retention times, it is safe to assume that the peak widths for the two solutes are approximately the same. Equation 12.1, therefore, is written as... 

Quantitative Calculations In a quantitative analysis, the height or area of an analyte s chromatographic peak is used to determine its concentration. Although peak height is easy to measure, its utility is limited by the inverse relationship between the height and width of a chromatographic peak. Unless chromatographic conditions are carefully controlled to maintain a constant column efficiency, variations in... 

With highly efficient chromatographic columns, very small amounts of complex mixtures can be separated in the liquid phase. Generally, the separated components cannot be positively identified by LC alone. 

The curves show that the peak capacity increases with the column efficiency, which is much as one would expect, however the major factor that influences peak capacity is clearly the capacity ratio of the last eluted peak. It follows that any aspect of the chromatographic system that might limit the value of (k ) for the last peak will also limit the peak capacity. Davis and Giddings [15] have pointed out that the theoretical peak capacity is an exaggerated value of the true peak capacity. They claim that the individual (k ) values for each solute in a realistic multi-component mixture will have a statistically irregular distribution. As they very adroitly point out, the solutes in a real sample do not array themselves conveniently along the chromatogram four standard deviations apart to provide the maximum peak capacity. 

This novel manifestation of the gas chromatographic separation demands that Our fundamental understanding of the GC method-invariably of single-dimensional scope-is challenged as follows concepts of column efficiency and separation are now Supplanted by a need to compare the performances of two columns operating... 

Purification of aequorin. The purification method of aequorin reported by Shimomura et al. (1962) was essentially the repetition of column chromatography on DEAE-cellulose, the only usable, efficient chromatographic adsorbent available at the time. Since then, various different types of chromatographic media have been developed, and the purification method has been steadily improved. 

Xt is very difficult to provide an optimum set of conditions for operation of a liquid chromatograph under overload conditions due to the coiq>lex interactions among a large number of parameters [591,592,595,608,620,625]. The following general observations seem to be applicable in most cases. The column efficiency should be as high as possible and separatimis should be carried out using concentration overload conditions. The production rate of a... 

Figure 1.9 illustrates the relationship between resolution, the separation factor, the average capacity factor and the column efficiency for some real chromatographic peaks [lOS]. The central portion of the figure illustrates how resolution increases with the capacity factor for a fixed separation factor and column efficiency. At first the resolution increases quickly as the... 

The physical properties of the mobile phase, mainly viscosity, diffusivity and solubility, affect the flow characteristics, column efficiency (kinetics), and retention (thermodynamics) in the chromatographic process. These physical properties are affected by temperature. Chromatographic techniques, although basically simple in... 

It is difficult to compare separation techniques in any general way. Comparison may be based on the traditional figures of merit, such as resolution Rs (including column efficiency N, selectivity, retention, and peak capacity), chromatographic speed, sample capacity, sensitivity, detection and column impedance, as well as breadth of application. Usually a tradeoff between these attributes is found. Berger [26] has compared GC, pSFC, cSFC, LC and CE on the basis... 

Tanaka, N., Kobayashi, H., Ishizuka, N., Minakuchi, H., Nakanishi, K., Hosoya, K., Ikegami, T. (2002). Monolithic silica columns for high-efficiency chromatographic separations. J. Chromatogr. A 965, 35-49. 

The strategy employed for choosing a particular chromatographic separation generally entails maximizing the column efficiency and, at... 

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