Enthalpy-controlled polymer HPLC

In this case, enthalpic interactions within the HPLC system exceed the exclusion effects (Eigure 16.3b). The retention volumes of polymer species as a rule exponentially increase with their molar masses. The limitations of the resulting procedures were elucidated in Section 16.3 the retention of (high)polymers is usually so large that these do not elute from the column (Section 16.6). Therefore, the majority of enthalpy controlled HPLC procedures is applicable only to oligomers—up to... 

In this case, the enthalpic interactions within the HPLC system exceed the exclusion effects (see Figure 3(e)). The retention volumes of polymer species as a rale exponentially increase with their molar masses. The important limitation of the resulting procedures was presented in section 11.5.2.3. The retention of (high) polymers is usually so intense that the latter do not elute from the column any more. Therefore, the majority of enthalpy controlled HPLC procedures is applicable only to ohgomers - up to molar mass of few thousands g.mol. Still, the reduced sample recovery may affect results of separation even in case of oligomers. The selectivity of enthalpy driven HPLC separation is much higher than in the case of SEC but, naturally, the sequence of molar masses eluted from the column is reversed. If the effect of enthalpy is reduced, problems with sample recovery are mitigated - but at the same time the separation selectivity is reduced. 

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