Eluent reservoir

Figure 6.27c, this procedure is illustrated by showing the band of the mixture throughout the whole width of the chromatographic plate [26,27]. In the next stage, the development of the chromatogram proceeds. It is performed by the introduction of an appropriate developing solvent into the eluent reservoir. It is recommended that at hrst a small quantity of the eluent be introduced into the reservoir to wash the reservoir walls and eliminate remnants of the sample solution. An example of separation of the sample mixture using this procedure is shown in Figure 6.28. Even a few milliliters of the sample solution can be applied with this mode. However, it depends on the sample mixture.

Figure 3. Set-up of a correlation HPLC system. The constant water flow is controlled by a PRBS pattern which directs the flow to either the sample or the eluent reservoir driving the appropriate plunger forward. A 6-way rotary valve is placed at the outlet of the eluent reservoir to allow single injection experiments.

Analyses were done on a Dionex Model 14 Ion Chromatograph (IC), equipped with a Waters WISP 7 autosampler, Linear recorder, and interfaced with a Hewlett-Packard 3354 Laboratory Automated System. The principal components of the IC, shown in Figure 2, are (A) eluent reservoir, (B) pump, (C) injection valve, (D) separator column, (E) suppressor column, (F) conductivity cell, and (G) conductance meter with a recorder (integrator). 

Figure 4.2 A schematic diagram of an integrated polymer monolith NCE with ESI-MS detection, (a) 1, separation channel 2, double-T injector 3, ESI source 4, eluent reservoir 5, sample inlet reservoir 6, sample waste reservoir 7, eluent waste reservoir that houses a porous glass gate 8, side channel for flushing the monolithic channel and 9, ESI emitter, (b) Cross-sectional view of reservoir 7, showing the position of the semipermeable glass gate, (c) Image of on-chip junction between the separation channel and the ESI emitter [25].

Despite such measures, LLC columns with insoluble stationary phases are not very stable, for instance due to a disturbance of the system every time a sample is injected. The reproducibility of retention data on these LLC columns is generally unsatisfactory, and aging of the column tends to occur rapidly. Apparently, the stationary phase is not merely dissolved from the column because of its solubility in the mobile phase, but it may also be eroded from the column because of mechanical processes (shear forces) or by a solution-precipitation mechanism, which causes the stationary phase to be redistributed within the column. These effects may be enhanced by temperature changes within the column, due to viscous heat dissipation and inadequate temperature control. Indeed, thermostatting of the column (and the eluent reservoir) is vital for the proper operation of LLC systems. 

Cavitation is a general operation problem, which can be solved by the use of tubings with a higher internal diameter or by increasing the pressure at the suction side of the pump. The easiest way to increase the pressure is to lift the eluent reservoir to a higher level than the pump inlet. If this is not sufficient the pressure in the solvent... 

Solvents and eluents must not be stored in plastic bottles because plasticizers and other low-molecular compounds may diffuse into the liquid. Eluent reservoirs should always be capped, either gas-tight or not depending on whether the solvents are stored or in use. Figure 4.1 shows a solvent supply vessel with aU possible accessories heating (for thermostating), reflux condenser, magnetic stirrer, vacuum pump, inert gas line and excess temperature control. 

Column 2. Spectrophotometer 3. Recorder 4. Eluent reservoir 5. Pump. 

A radionuclide generator consists of a glass coluiim filled with an adsorbent material such as aluminum oxide or an ion-exchange resin to which the parent nuclide is bound (Richards 1966). The column is fitted with a filter at the outlet to retain particulate matter. On top is the elution platform, where an evacuated sterile vial is connected with the outlet of the column through which saline or another suitable eluent is drawn from the eluent reservoir. 

Turn the compressed air valve on and adjust the main pressure gauge to 80 psi. This provides a head pressure to the eluent reservoir. 

Eluent reservoir. Electrical generation of eluent ions is used in some cases. 

As expected, the addition of barium hydroxide results in a somewhat higher retention of all components this effect is more pronounced with lactose and cellobiose. The retention increase is attributed to the complete removal of carbonate, which precipitates in the eluent reservoir as low-soluble barium carbonate. The improved peak shape for ribose that Angyal [225] attributes to the complexation of sugar molecules by alkaline-earth metals, especially by Sr(II) and Ba(II), is remarkable. Sugar molecules with a six-membered ring and a sequence of an axial (ax), an equatorial (eq), and an axial (ax) hydroxide group bind alkaline-earth metals very strongly. Ribose has such a structure as shown here ... 

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