Analysis of polycyclic aromatic hydrocarbons using porous material MCM-41 as a sorbent

Abstract

The feasibility of employing the mesoporous silicate MCM-41 as a sorbent for sampling ambient polycyclic aromatic hydrocarbons (PAHs) was investigated. The performance of MCM-41 as a sorbent for PAHs was assessed by using standard mixtures and field sampling of seven target species: naphthalene, acenaphthylene, acenaphthene, fluorene, phenanthrene, fluoranthene, and pyrene. Quality assurance measurements, such as analytical precision, linearity, and recovery, were determined via addition of external, surrogate, and internal standards. To test the field applicability of MCM-41, the exhaust of motorcycle and diesel bus were sampled as the sources of PAHs. The performance of MCM-41, which was evaluated against that of commercially available sorbents XAD-2 and XAD-16, showed comparable results. In the case of four-stroke motorcycle exhaust, both MCM-41 and XAD-2 exhibited similar sorption characteristics for the seven target PAHs at concentrations of 15 to 2.8 × 10⁵ ng m⁻³ in the exhaust. Diesel bus exhaust sampled through a dynamometer was examined using commercial XAD-16 as the reference. The concentrations of naphthalene, acenaphthylene, acenaphthene, fluorene, and phenanthrene were found to be in the range of 10 to 2.5 × 10⁴ ng m⁻³. Other than naphthalene, which had a low recovery (20–30%) because of its high volatility, the recoveries of MCM-41 for most target PAHs show a trend similar to those of the XAD materials in the study, demonstrating the high applicability of MCM-41 as an enrichment medium for ambient PAHs.