Evaluating the Limitations of One-Dimensional High-Temperature Gas Chromatography - FID for Wax Solution Analysis: A...

Wax deposition in petroleum systems is intrinsically connected with paraffin wax composition, yet their quantitative characterization by one-dimensional high-temperature gas chromatography with flame ionization detection (HTGC-FID), as prescribed by ASTM D5442, remains challenging. In this work, we systematically quantify the main sources of error affecting HTGC-FID analysis of paraffinic systems and benchmark the chromatographic results against differential scanning calorimetry (DSC). The results demonstrate that solvent-based sample preparation leads to nonhomogeneous solutions at the colloidal scale due to paraffin aggregation, introducing significant sampling errors that intensify with increasing molecular weight, whereas an additional error source arises from incomplete volatilization of heavy paraffins in HTGC. A trade-off between loss of detectability at high dilution and aggregation effects at high concentration was observed, impacting quantitative analysis. The absence of reliable retention time patterns for nonlinear paraffins highlights the intrinsic limitations of one-dimensional HTGC-FID for their structural assignment, emphasizing the need for more advanced chromatographic approaches for comprehensive wax characterization.