Second dimension retention indices in "normal" orthogonality comprehensive two-dimensional gas chromatography using...

This work builds upon recent developments in the field of second dimensional (2D) retention indices (RI) for use in comprehensive two-dimensional gas chromatography (GC×GC), expanding application to the most commonly used "normal" orthogonality column configuration, where 2D RI are rarely employed. Initially, one dimensional retention indices for 80 wastewater pollutants were determined by GC-MS on a mid-polar ZB-50 column. In order to determine the 2D RIs for peaks detected in wastewater extracts separated by GC×GC -MS, a single injection of a ten-compound standard mix allowed the construction of model-generated isovolatility curves. These curves were used for the determination of 2D RIs of compounds initially identified on the basis of the mass spectral match factor and 1D RIs. Good agreements (average deviation of 1.7%) were observed between the calculated 2D RIs and the measured reference RIs for these compounds. These results show that this approach provides an additional level of confidence for the identification of compounds detected in GC×GC-MS and demonstrates the potential of this approach for improved compound identification in non-targeted analysis.