Solvent expanded

Coupling HPLC to a mass spectrometer is far more complicated than in a GC system because of the large amount of mobile phase solvent expanding into the system (see Table 1 for expansion volumes). Typical mobile phase flow rates for HPLC are 0.5-2 mL min which translates into gas flow rates of 100-3000 mL min . ... 

Tab. 1.1 Comparison of chlorom lethylated styi renic gel-type resins and solvent expanded analogs.

The volume of many liquid solvents expands with increasing temperature. What happens to the concentration of a solution made with such a solvent as the temperature of the solution is increased ... 

Step a Solvent Expanded solute solvent Step c... 

In SEE, instead of a liquid solvent a supercritical fluid is used for extracting specific compounds from a solid or liquid matrix. A simple schematic of this process by Reverchon [20] is shown in Eig. 13. In the left-hand side of each of the figures, the pressurized supercritical fluid is introduced into the reactor El Its pressure and temperature are chosen so as to dissolve as much of the desired compound as feasible. The pressure is quenched at the entrance to a vessel Se that receives the reaction product. The solvent expands and releases the solute, which collects at the bottom of the receptacle, while the gas is released from the top, repressurized and recirculated. 

Excluded Volume Effects.—Because of intramolecular segment-segment interactions, a polymer chain in a thermodynamically good solvent expands by a factor defined by... 

HYNES - I do not understand why you say that intermolecular streching motions of the solvent, expanding or compressing the first solvation shell, occur on the same time scale (20 fs) as the reactive process. We see no evidence for this. The success of the frozen solvent, non-adiabatic solvation model, which ignores all solvent motions, indicates that all solvent dynamics can be ignored for the standard Cl + CH3CI case. 

The size of random chain coils, predominantly in solutions of polymers, can be obtained by several experimental techniques. The size of the molecular coil of a particular polymer is dependent on the solvent (Fig. 2.7). A good solvent expands the coil. A poor solvent, on the other hand, causes shrinkage. In between these two extremes, so-called theta solvents are found (see Chapter 4). Typical of these... 

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