Multipurpose detection system in Gas Chromatography featuring element selective detection (C, H, N, S, O) with generic quantification in complex samples while maintaining structural elucidation capabilities

The use of biofuels and more renewable and sustainable energies will require the characterization of new feedstocks, processes and products. This is a difficult task due to the complexity and variety of their matrices and the analytical challenge that poses the accurate determination of the great variety of volatile N-,S-,O-containing compounds, whose presence, even at trace levels, limit their potential applications. In this context, GC-MS is well-established as it provides either universal detection with structural identification or compound-specific detection. However, its compound-dependent ionization demands for specific standards. Additionally, it is limited in screening for specific families (e.g. S, N and O-compounds). Given the relevance of the heteroatoms abovementioned, selective detectors such as NCD and SCD have been developed. Unfortunately, spectroscopic detectors suffer from matrix and quenching effects when analysing complex unresolved samples. Notably, no adequate H and/or O-selective detectors exist.
We have recently demonstrated that online combustion of all the GC-eluting compounds into the same volatile species (CO₂, H₂O, NO and SOx) makes their detection compound-independent. Detection limits for N and S (well below pg levels) are significantly lower than those obtained with the standard dedicated NCD and SCD. Importantly, all these exceptional features are offered together with universal detection, through the Carbon detected in every organic compound as CO₂, and while still maintaining the identifying capabilities of the GC-MS instrument by simply actuating a switching valve. This is also the first detector able to measure H/C molar ratios to assess the unsaturation degree of the different sample fractions. The prototype holds great potential as well for the selective and generic quantification of oxygen-containing compounds (WO/2017/114654) when resorting to isotopically-labelled ¹⁸O-oxygen as combustion gas to discriminate the natural oxygen (mostly ¹⁶O) present in oxygenates found in complex oil samples (diesel, biooil) with excellent detection limits (range of 100 pg O)