Columns packing techniques

This is an example for a case where we have to increase the inlet pressure to reduce analysis time, but we also have to explore ways to improve the column packing technique. A comparison of the results shows that the very well-packed column generates ten times more plates per unit time than the poorly packed column. In Eq. (2 ) r is multiplied by 4 and li is di vided by 2.5. Thus, analysis time and column length are divided by 10 and... 

The same factor is used for the scale-up of the sample load. The translation of an analytical method to a preparative system is obviously dependent on the sorbent characteristics of the preparative column. Several reviews on preparative methods, column-packing techniques, theory, and equipment design have been published [132-135,145]. Specific examples of the application of preparative procedures are listed in Table 5.3. 

A decrease in h. This is achieved by using good column packing techniques. 

Appendix A2.2 gives a detailed description of different column packing techniques and their standard operating procedures. 

Thixotropic and dilatant behavior of the suspension can be monitored by viscosi-metric measurements as a function of shear rate and the duration of the experiments. Studies with a 25 wt.% suspension of LiChrospher 100, 7 gm in a mixture of dioxane-cyclohexane-n-octanol (45/45/10, v/v/v) have shown that the suspension has rather low thixotropic and pseudo-elastic behavior (Hallmann, 1992). The packing pressure of the axial dynamic column packing technique has a significant influence on the column performance (Tab. 3.13). 

Generally, the expert chromatographer relies on his own column packing techniques, because comnercial packed columns for HPLC do not always provide optimum efficiency, but are less vulnerable to the treatment of less experienced chromatographers. 

It should be noted that variables other than particle size and column length may influence the net transition toward hi er efficiencies. These factors include physical advantages such as better particle size distribution and more efficient column-packing techniques, as well as more fundamental chemical... 

This sounds too good to be true. . . and to some extent it is. As we reduce particle size, other problems arise and must be addressed. Table XVin summarizes the application of the above analysis to the question of Optimum particle size for different compounds. First, we see that an optimum particle size for proteins with M 10,000 is 1 itm or less. While such particles have been made (772, 774), procures for packing them into efficient columns have not yet been reported. So new column packing techniques will have to be learned, possibly combined with change in the derign of the column blank, frits, fittings, etc. 

Microscopic nonuniformities originate on one hand from the bare fact that particles are used to form the bed. On the other hand, the pattern in which the particles are arranged relative to each other is also important. As a consequence, the A term of the van Deemter equation is proportional to the particle size and can be influenced by the column packing technique. 

The Preparation of the Pirkle Stationary Phases The Preparation of Cellulose and Amylose Stationary Phases The Preparation of the Macrocyclic Glycopeptides Phases The Preparation of the Cyclodextrin Based Stationary Phases Column Packing Techniques... 

The suspension is pressed into the empty column. which is fitted with a frit on its far side, by means of a constant-pressure pump (pressure filtration). The usual packing pressure for a standard analytical column (250x4 mm i.d.) is between 40 and 60 MPa. In this case. l.7-2.0g of stationary phase has to be suspended in ca. 30-50mL of suspension fluid. Detailed discussion of column packing techniques is given in [73], [19], [76]. 

COLUMN CARE AND SUPPLY 6.1 Column packing techniques... 

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