An Automated HPLC Method for SARA Fractionation of Asphalts: Operational Assessment and Comparison with ASTM D4124
Giovanni Polacco1, Sara Filippi1, Chiara Riccardi1
1Department of Civil and Industrial Engineering, University of Pisa, Largo Lucio Lazzarino, 1, 56122 Pisa, Italy.
ACS Omega
|May 11, 2026
Summary
This study introduces an automated HPLC method for asphalt SARA fractionation, offering a faster and more reproducible alternative to the traditional ASTM D4124 standard. The research clarifies differences between methods, aiding consistent asphalt characterization.
Area of Science:
- Petroleum Chemistry and Materials Science
- Analytical Chemistry and Chromatography
Background:
- Asphalts are complex mixtures characterized by saturates, aromatics, resins, and asphaltenes (SARA) fractions, crucial for understanding material properties.
- Current standard methods like ASTM D4124 for SARA analysis are laborious, solvent-intensive, and operator-dependent, limiting widespread adoption of advanced techniques.
- Existing High-Performance Liquid Chromatography (HPLC) alternatives face challenges due to methodological variability and difficulties in interpreting results across different schemes.
Purpose of the Study:
- To develop and validate an automated HPLC workflow for SARA fractionation of asphaltic materials.
- To systematically compare the proposed HPLC method with the established ASTM D4124 standard.
- To elucidate the origins of discrepancies between HPLC and ASTM D4124 SARA compositions and provide guidance for data interpretation.
Main Methods:
- Development of an automated High-Performance Liquid Chromatography (HPLC) system for SARA fractionation.
- Application of the automated HPLC workflow to four different penetration-grade asphalts.
- Systematic comparison of HPLC results with those obtained using the ASTM D4124 standard method.
- Analysis of fractions isolated by ASTM D4124 and selected model compounds to understand method-specific differences.
Main Results:
- The automated HPLC workflow demonstrated practical implementation with highlighted critical steps for reproducibility and inter-laboratory transferability.
- Systematic differences between HPLC- and ASTM D4124-derived SARA compositions were observed and attributed to distinct separation mechanisms and operational cut points.
- These differences stem from the continuous distribution of molecular polarity in asphaltic materials, making SARA classification inherently method-dependent.
Conclusions:
- The automated HPLC method offers a more efficient, reproducible, and transferable approach to SARA fractionation compared to ASTM D4124.
- Understanding the method-dependent nature of SARA classification is crucial for accurate asphalt characterization.
- This work provides practical guidance for interpreting HPLC-SARA data, promoting more consistent and reliable asphalt analysis.
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