Evaluation of Polycyclic Aromatic Hydrocarbons in Asphalt Binder Using Matrix Solid-Phase Dispersion and Gas Chromatography

Journal of Chromatographic Science, Vol. 47, October 2009 Evaluation of Polycyclic Aromatic Hydrocarbons in Asphalt Binder Using Matrix Solid-Phase Dispersion and Gas Chromatography Paulo R.N. Fernandes1, Sandra de A. Soares1, Ronaldo F. Nascimento2, Jorge B. Soares3, and Rivelino M. Cavalcante4* 1Laboratório de Polímeros - Departamento de Química Orgânica e Inorgânica, Universidade Federal do Ceará, bloco 940. Av. Humberto Monte, s/n – Campus do Pici. CEP: 60455-760 - Fortaleza – CE, Brasil; 2Laboratório de Análise Traço – Departamento de Química Analítica e Físico Química, Universidade Federal do Ceará, bloco 939. Av. Humberto Monte, s/n – Campus do Pici. CEP: 60455-760 – Fortaleza – CE, Brasil; 3Laboratório de Mecânica dos Pavimentos - Departamento de Engenharia de Transportes, Universidade Federal do Ceará, bloco 703. Av. Humberto Monte, s/n – Campus do Pici. CEP: 60455-760 - Fortaleza – CE, Brasil; 4Laboratório de Biogeoquímica Costeira, Setor de Análise Orgânica, LBC-Org – Instituto de Ciências do Mar-LABOMAR – Universidade Federal do Ceará. Av. Abolição, 3207 – Meireles, CEP: 60165-081 – Fortaleza – CE, Brasil Abstract A method developed for the extraction and analysis of polycyclic aromatic hydrocarbons (PAHs) in the asphalt binder using a matrix solid-phase dispersion (MSPD) and gas chromatography is presented. The MSPD method was proposed as a rapid and easy approach to determining PAHs present in the maltenic phase of asphalt binder extracted through a mechanical shaking and sonication of the material. The recovery rates ranged from 62.77–89.92% (shaking) and from 56.54–93.6% (sonication) with relative standard deviations lower than 8.8%. The study shows that the recovery rates using shaking and sonication extractions are not significantly different at the p < 0.05 level. The limits of detection and quantification ranged from 0.7–1.8 mg/kg and 2.2–5.6 mg/kg, respectively. The proposed analytical method was applied to determine PAH levels in an asphalt binder from Brazil. The main PAHs found were BbF, BaP, Per, IncdP, DahA, and BghiP, with average concentrations of 10.2–20.7 mg/kg, but the PAHs Ace and Acy were not detected. However, Nap, Fl, Phen, Ant, Flr, Pyr, Chry, BaA, and BkF were present in average concentrations amounting to less than 10 mg/kg. The results showed that the MSPD method is potentially a valuable tool for the determination of PAHs in the asphalt binder. dark brown to black cement-like thermoplastic material (1) with an extremely complex mixture containing a large number of highmolecular weight organic compounds (2). The asphalt binder constituents can be separated into two fractions: asphaltenes (polar fraction) and maltenes (apolar fraction). Chemical fractionation is the method most commonly used for the quantification of asphalt binder constituents (3). The SARA method separates the asphalt binder constituents into four fractions: saturates, aromatics, resins (fraction of maltenes soluble in apolar solvents) and asphaltenes (Figure 1), although the most important chemical family is the aromatic fraction (45.1–95.0%) (1,4). The asphalt binder (or bitumen) is mostly used in paving operations. The remaining uses include waterproofing and insulation. Asphalt binders used for the construction of roads offer a variety of properties such as a good resistance to aging and Introduction Asphalt binder is the product of the distillation of crude oil in petroleum refining. It ranges from a * Author to whom correspondence should be sent: R.M. Cavalcante, Instituto de Ciências do Mar (LABOMAR), Universidade Federal do Ceará, Av. Abolição 3207-CEP 60165-081, Fortaleza, CE, Brasil, email . Figure 1. Asphalt composition: saturates, aromatics, resins, and asphaltenes [adapted from Klein et al. (3)]. Reproduction (photocopying) of editorial content of this journal is prohibited without publisher’s permission. 789 Journal of Chromatographic Science, Vol. 47, October 2009 high-performance traffic loading (5). However, the techniques used in the production and application of this material frequently involve a hot-mix asphalt production (6). The emissions generated during the production and application of asphalt binders contain a large number of substances, some of which are potentially harmful to the health of those involved (7,8). Exposure to compounds contained in the asphalt binder can occur through inhalation or even absorption through the skin during application to streets and roads (1,7). Another way in which the asphalt binder constituents can be released to the environment is through the degradation of the road surface, this being an important source of contamination of water bodies (9,10). Polycyclic aromatic hydrocarbons (PAHs), which may be generated in various asphalt operations, are some such constituents that may be hazardous to workers’ health (8). The PAHs are mainly released during the burning of petroleum and its derivatives (11). PAHs with 4–6 aromatic rings are highly mutagenic and carcinogenic, while those with 2–3 aromatic rings are highly toxic despite being less mutagenic (12). In addition, PAHs form part of the group of compounds known as persistent organic pollutants (POPs), which adversely affect the environment and are the focus of many research studies (9–11,13–17). Statistical data have revealed evidence of a risk of cancer, and there is a relation between carcinogenesis and the molecular structure of PAHs (18). This leads to a need for adequate procedures to detect PAHs in asphalt and the correct use of the material in order to avoid environmental and human contamination (18). Few studies on asphalt binders have focused on the determination of the PAH content and, therefore, it is of great interest to develop an efficient method that can contribute to evaluating the real contribution of the asphalt industry to PAH contamination. In general, the specific determination of mono-, di-, and poly-aromatics (maltenes) involves the quantification of the total form (3), and a second separation stage is required to obtain these forms separately, which makes the procedure highly time-consuming and requires more materials (solvent and adsorbent). The matrix solid-phase dispersion (MSPD) can be used as an alternative technique to the classical extraction methods because it allows the simultaneous extraction and clean-up of analytes from solid samples considered complex with a significant reduction in the solvent consumption and without requiring expensive instrumentation (19–21). MSPD has been mainly used for the extraction of organic environmental pollutants in food and biological matrices (21–23), but to our knowledge it has not been applied to the determination of PAHs in asphalt binder. This study was performed in order to explore MSPD as an analytical method for the detection and the determination of 16 U.S. EPA (United States Environmental Protection Agency) PAH levels in an asphalt binder originating from the southeast (...truncated)