2D GC sees petroleum additives more clearly

Agilent Technologies has announced a two-dimensional gas chromatography (GC) method that enhances resolution when analysing oxygenated additives and aromatics used to improve performance and reduce emissions in gasoline.

Gasoline, a complex mixture, contains low-boiling aromatic compounds and polar additives such as ether and alcohol.

Quantitative measurement of these additives using GC is difficult because there is no single column that can completely and quickly separate the target compounds from the complex hydrocarbon matrix.

Two-dimensional GC solves this problem by coupling two GC columns, each with different selectivity.

Unresolved analytes eluting from the first column transfer to the second column, where complete separation occurs.

Agilent application chemists used an Agilent 6890N GC system equipped with a Deans switch to heart-cut the unresolved analytes in the gasoline matrix.

This plumbing design makes it easy to determine cut times, allowing easy method setup.

The switch also improved performance by eliminating carryover and minimising peak tailing for very polar compounds.

This allows greater confidence in results for low concentrations of polar additives.

Moreover, the 6890N's electronic pneumatics control provided retention time precision that allowed narrow cut times for enhanced resolution and a backflushing technique for faster analysis time.

System calibration and quantitative results demonstrated excellent performance.

The two-dimensional GC method complies with European Standards EN 13132 for oxygenate additives in gasoline and EN 12177 for benzene in gasoline.

For further information, request Agilent application note 'Two-dimensional gas chromatographic analysis of oxygenates and aromatics in gasoline using a heart-cutting technique', Agilent publication number 5988-6696EN.

This note is available without charge from any Agilent sales office or its website.