Rtx-440&Rtx-XLB: LowBleedand
Excellent Resolution inLessThan
12Minutes (Figures 1a& 1b).
Decachlorobiphenyl elutes off of the “XLB” phase in 11.5minutes, while the target
compounds listed inEPAMethod 8080 are 80% resolved onboth columns. Optimization of
the expanded list of compounds found inEPAMethod 8081A resulted in 80% resolution of
the 32 target compounds (plus the surrogates) on theRtx-440, with the exception of
kepone and endrin aldehyde. TheRtx-XLB phase under the same conditions has two
poorly resolved pairs: endrin/2,4’-DDT& endosulfan II & kepone. The clear advantage of
this column pair is the rapid analysis and low bleedwithout a sacrifice in resolution. These
columns have the same elution order for theEPA 8080 pesticides, which is a disadvantage
of this application. Although there are elution order differences for the expanded list and the
retention times are different for all of the chlorinated pesticides there is still a need to find a
more dissimilar stationary phase as a confirmation column.
