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

Abstract

The present research is focused on the offline combination of normal-phase LC to double-oven GC x GC-quadrupole MS. Initially, a diesel sample was subjected to automated LC x 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 x GC analysis using an apolar-polar column combination. The GC x 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 x GC were: (i) the high first-dimension LC selectivity; (ii) the injection of high sample amounts in the GC x GC system, enabling the detection and quantification of a series of low-amount diesel constituents; (iii) improved GC x GC operational conditions for each heart-cut with respect to direct GC x GC.

Comprehensive Liquid Chromatography and Other Liquid-Based Comprehensive Techniques Coupled to Mass Spectrometry in Food Analysis

“…Among the chromatographic combinations, the hyphenation of liquid chromatography to gas chromatography in a comprehensive way (LC × GC) or, more recently, to comprehensive two-dimensional gas chromatography (LC-GC × GC) has proven to be worthy of attention. − The reason for this attractiveness, in the first case, is related to the fact that a complete separation of complex mixtures using 1D-GC is often difficult to achieve. With real-world samples usually being characterized by a heterogeneous nature, which comprises a variety of chemical families and constituents, and present in a wide range of concentrations, the LC preseparation allows one to isolate more homogeneous groups of compounds prior to GC analysis in order to avoid exceeding the capability of a monodimensional GC system.…”

“…From an instrumental point of view, the introduction of a large volume of liquid effluent into a GC injector represents one of the most important issues. Nowadays, the advent of commercially available fully automated online LC-GC interfaces has greatly reduced issues deriving from a high degree of manual operations, as loss of sample during the transfer and evaporative steps, as well as contamination during the transfer of the LC fraction to the GC injector. , When LC and GC are coupled, the resulting analytical method is greatly influenced by the differences in analysis times of the two dimensions: the inability to perform the GC run in a simultaneous manner with LC requires the latter to be operated in the stop-flow mode. As a consequence, one of the main limitations in a comprehensive LC × GC approach is the GC total run time (analysis + cooling) which generates very long analysis times (typically >3 h) in proportion with the number of LC fractions transferred.…”

“…The occurrence of MO migration from recycled paper and board used in food packaging was explored by coupling an LC silica column separation to a GC × GC system with MS and FID for identification and quantification purposes, respectively . LC-GC transfer occurred by the retention gap technique and partially concurrent eluent evaporation through the Y-interface: , exploiting the LC step, MOSH and MOAH fractions were analyzed separately in GC × GC. The instrument configuration and GC conditions were the same as reported in ref .…”

Extended characterization of a vacuum gas oil by offline LC‐high‐temperature comprehensive two‐dimensional gas chromatography

“…To enhance the selectivity, the addition of a dimension operating in a dense phase (LC or SFC) proved to be complementary to the high peak capacity of GC Â GC systems [11]. In this way, the addition of a heart-cut dimension was used to reduce coelution problems, including in petroleum field, as, for example, LC-GC Â GC [12,13] or SFC-GC Â GC [14]. More recently, total comprehensive 3-D system LC Â GC Â GC [15] was shown inducing much detailed information but in high duration time.…”

Multidimensional GC coupled to MS for the simultaneous determination of oxygenate compounds and BTEX in gasoline

“…GC-based techniques are the most widely applied in BTEX and oxygenate compounds analysis. The complexity of such a matrix has led to the use of comprehensive 2-D GC (GC Â GC) for the analysis of BTEX and heavier compounds in gasoline [10,11] and for oxygenate compounds [12] due to the greater amount of available peak space in a 2-D chromatogram than in a single-axis one and, hence, much greater peak capacities [13]. A combination of LC pre-separation coupled off-line with a PTV-GC Â GC system has been exploited for the analysis of a diesel sample [14].…”