Reversed‐phase LC‐GC with a nitrogen‐phosphorus detector using a loop‐type interface combined with a sandwich‐type phase separator

Abstract

Abstract Reversed phase LC is coupled to capillary GC by means of an on‐line extraction of the LC eluent. The extract is transferred to a loop‐type LC‐GC interface equipped with an early vapor exit. Using a phase switch from an aqueous reversed‐phase (RP)LC solvent to an organic solvent facilitates the introduction of the analyte in the GC system, since organic solvents such as hexane, pentane, and dichloromethane are more appropriate for the GC‐injection technique used in this study. As the partition coefficient of an organic solvent/aqueous system is correlated to the retention mechanism of reversed phase LC, the method has a general potential in LC/GC interfacing, viz. the extractability a component from the LC mobile phase eluting above a certain capacity factor from a RPLC column can be expected to be efficient. The method is applied to the determination of residues of the fungicide fenpropimorph in barley, oats, rye, and wheat. Another application of the interface which is feasible is the on‐line extraction of aqueous samples prior to large volume injection on GC‐NPD. The potential of the interface for the determination of residues nitrogen containing herbicides is estimated.