Loading capacity/efficiency

The technique of column overloading is only feasible if more than adequate resolution is possible between the solute of interest and its nearest neighbor. Many samples require a column to be constructed that will only just separate the solutes of interest and under these circumstances the loading capacity must be increased without overloading the column. It has been shown in earlier chapters that the maximum sample (mass or volume) that can be placed on a column is proportional to the plate volume of the column and the square root of its efficiency. Thus, the maximum sample mass (M) will be given by... 

The actual loading capacity always depends on the sample composition and the separation problem. As a rule the volume of the loaded sample should not exceed 5% of the column volume. However, this recommendation is valid only for preparative runs. For analytical applications when a high resolution is needed, the volume of the injected sample should be about 1% of the total column volume or even less. For a preparative run on a 1000 X 200-mm column (bed height 60 cm), two different sample volumes were injected. If the sample volume is 0.3% of the total bed volume, the separation is more efficient... 

Standard Derricks 501. Load Capacities 506. Design Loadings 508. Design Specifications 511. Maintenance and Use of Drilling and Well Servicing Structures 515. Derrick Efficiency Factor 521. 

Worm, double-enveloping Increased load capacity Lower efficiencies... 

Working load. The efficiency drops off quickly as the load decreases. The more the load is decreased from 100% rated capacity, the steeper is the decline in the machine performance. The decline in performance depends on the machine and the control system. For example, at 70% of full load, the ratio of the part-load efficiency to the efficiency at full-load might vary typically between 0.95 and 0.85, depending on the machine and the control system. Twin-spool machines have a better part-load performance than single-shaft machines. Part-load performance depends on the size of the machine. 

Both large-pore and nonporous sorbents have been successfully applied for large biomolecule separations. The fundamental distinction between these two particle types is the balance between efficiency of mass transfer and loading capacity. Porous... 

In preparative chromatography, selectivity and efficiency no longer have the same importance they do in analytical chromatography. A certain selectivity is required in preparative chromatography as everywhere else in order to achieve the separation, but other parameters are at least as important if not more so. These include the loading capacity of the stationary phase and the maximum speed (throughput) of the process. The three main economic criteria for a large scale separation process are... 

One particular dendrimer system was reported to have increased the loading capacity 10-fold over direct coupling of the oligonucleotide to the surface. Unfortunately, the presumed improvement in hybridization efficiency was not discussed in quantitative terms. Reusability of the array was a primary objective of the work. Again, quantitative information was not provided. As the authors note, the array withstood >7 actual hybridization stripping cycles and 30 simulated (lacking target) cycles. 

Open tubular columns enable the chromatographer to effect separations impossible by other techniques, for example, separation of isomers. Their use permits a smaller inventory of columns and a smaller selection of stationary phases. Their main advantage is their high efficiency and their disadvantage is their small load capacity. 

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