ConfirmationColumnSelection
Previouswork indicated that theUltraAqueousC18 stationary phase provided
enhanced selectivity for the target herbicides. Many different types of HPLC
stationary phaseswere evaluated as possible confirmation columns; such as the
UltraPFP (pentafluorophenyl), and IBD (intrinsically base deactivated), aswell as
thePinnacle II
TM
PAH andPhenyl phases. Thesewere all tested to establish if they
provided adequate separation, rapid analysis times and sufficient elution order
changes to qualify as a reliable confirmation column. Results of these studies
indicated that theAllure
TM
Basix phasemet all the necessary requirements.
Figure 1 demonstrates the problemswhen using either a standardC18 or even a
basedeactivatedC18 phase for theanalysis of these acidic herbicides. Figure 2
shows the significant analytical improvement whenusing theUltraAqueousC18
and theHPLC conditions listed inTable II. The chromatograms forMixA andB are
overlayed for clarity. Figure 3 chromatogramsweregenerated using these same
analytical conditions and theAllureBasix column. All of the runswere completed in
less than 17minutes and still provided adequate separations. TheUltraAqueous
stationary phase contains a polar embedded group inaddition to theC18
functionality, while theAllure’s highly retentive propyl cyano phase demonstrates a
very different selectivity for the target herbicides under the same analytical
conditions. Table III highlights both the differences in elution order and the shift in
retention times that are critical to obtaininggood confirmationof the identified
underivatizedanalytes.
