Optimized solid-phase extraction (SPE) for bitumen maltene fractionation: an accelerated, reliable, and resource-efficient approach

Bitumen fraction evaluation is an important tool for understanding the chemical composition of bitumen. This study comprehensively investigates Solid-Phase Extraction (SPE) for bitumen maltene fractionation, emphasizing that reliable separation cannot be achieved by simply scaling down column chromatography (CC) conditions. An unaged and unmodified paving bitumen with a penetration grade of 50/70 from refinery A was used to evaluate operational factors. Fraction mass distributions, Colloidal Index (CI), Fourier Transform Infrared (FTIR) spectroscopy, and multivariate analyses including Principal Component Analysis (PCA) and Euclidean distance were applied for quantitative assessment. Separation performance is governed by the balance between driving force and flow resistance , which controls the recovery of fractions with different polarities. Suboptimal elution conditions lead to incomplete recovery of low-polarity fractions and overestimation of resins. Optimized conditions produce separation results that are highly consistent with those obtained by CC. Validation across six additional bitumens further demonstrates the applicability and reproducibility of the optimized SPE approach. An overall correlation analysis of all fraction mass distributions demonstrated a strong linear agreement between the SPE and CC methods (r = 0.979). Mass differences between SPE and CC were mostly ≤1.5 wt%. Evaluation of spectral differences using Euclidean distance showed that values ranged from 5 to 20 under unoptimized conditions, while after optimization the range decreased to 1–4, indicating markedly improved spectral similarity between the SPE and CC fractions. The optimized SPE method is accelerated, reliable, and resource-efficient, cutting solvent and adsorbent consumption by roughly 90% and reducing elution time from 3 h to 15 min. This optimized separation approach shows strong potential for application in bitumen maltene fractionation.