Offline LC‐GC×GC in combination with rapid‐scanning quadrupole mass spectrometry

The present research is focused on the offline combination of normal‐phase LC to double‐oven GC×GC‐quadrupole MS. Initially, a diesel sample was subjected to automated LC×GC in order to define the elution windows of four fractions, viz. , saturated hydrocarbons, monocyclic aromatics, dicyclic aromatics, tri‐ + tetracyclic aromatics; each fraction was collected exploiting the LC system in a further analysis and subjected to large‐volume‐injection‐GC×GC analysis using an apolar–polar column combination. The GC×GC operational conditions were tuned in relation to the specific separation requirements of each heart‐cut. The main benefits of what can be defined as offline LC‐GC×GC were: (i) the high first‐dimension LC selectivity; (ii) the injection of high sample amounts in the GC×GC system, enabling the detection and quantification of a series of low‐amount diesel constituents; (iii) improved GC×GC operational conditions for each heart‐cut with respect to direct GC×GC.