IPRs Added Only to Sample Solution and Ghost Peaks

3 IPRs ADDED ONLY TO SAMPLE SOLUTION AND GHOST PEAKS 

The use of pennanently coated columns was not the only strategy to eliminate IPRs in eluents. The possibility of adding an IPR only to the solution of sample to be injected was successfully explored. It was suggested that ion-pairing in a sample is sufficient to provide improved reversed phase retention. The effectiveness of this stratagem has both theoretical and practical value. 

It definitively d onstrates that ion-pairing among hydrqthobic ions occurs in water—at variance with the Bjerrum s electrostatic modeling of ion-pairing (see Chjpto 

3 for further details) impairs the foundations of electrostatic retention models that neglect the importance of ion-pairing in the eluent [19,20] and confirms the need to treat the ion-pair formation at a thermodynamic level [21,22]. 

FIGURE 11.1 Split peak (1.380-1.436) of interconverting free and paired analytes if the rate of the process is slow compared to chromatographic retention timescale. 

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