Determination of Polycyclic Aromatic Hydrocarbons (PAHs) in Coffee Samples by DI-SPME-GC/MS

Abstract

Roasting is a crucial and essential step to produce quality coffee. However, it could lead to the formation of toxic and suspected carcinogenic or procancerogenic compounds, such as polycyclic aromatic hydrocarbons. In this work, a simple and easily automatable green procedure based on solid-phase microextraction coupled with gas chromatography for the analysis of acenaphthene, anthracene, benzo[ghi]perylene, benzo[a]pyrene, chrysene, fluoranthene, fluorene, naphthalene, and pyrene, in dark roasted and decaffeinated commercial coffees, was developed. The method was optimized for the determination of the analytes both in solid samples, such as ground coffee or coffee grounds, and liquids, such as espresso coffee, using a polyacrylate-coated fused silica fiber (85 μm) by direct immersion. The performance of the analytical method, developed in terms of sensitivity, reproducibility, and recoveries, proved to be suitable for the applications. Among the 9 polycyclic aromatic hydrocarbons investigated in the selected coffees, chrysene and pyrene were the most representative congeners with values ranging from undetectable to 95.6 ± 11 ng/g for chrysene and from undetectable to 404.7 ± 42.0 ng/g for pyrene. Benzo[a]pyrene was detected in two samples of dark roasted coffee which therefore had the highest toxicity/carcinogenicity in terms of toxic equivalent. The estimated limit of detection for benzo[a]pyrene in ground coffee and coffee grounds was 9.0 ng/g. About 30% of the PAHs were transferred to the infusion while the remaining part was retained by the coffee grounds.