Assessment of polycyclic aromatic hydrocarbons and derivatives in beer using a new cold fiber-solid phase microextraction system

Sample preparation assisted by a cooling system including solid phase microextraction (SPME) has received an increased interest in recent years. In this work, a new cold fiber (CF-SPME) system using thermoelectric cooling is proposed. The system consists of three thermoelectric coolers (Peltier), a heat sink, a recirculation module to dissipate the heat generated on the hot side, and an electric power source to generate the necessary voltage for the system. The Peltier keeps the SPME fiber cool during the extraction process.. This system was used to analyze polycyclic aromatic hydrocarbons (PAHs), and their nitrated (nitro-PAHs) and oxygenated (oxy-PAHs) derivatives, in commercial beers by gas chromatography coupled to mass spectrometry (GC/MS). The analyte?s extraction was optimized through Doehlert design. Optimal extraction conditions were obtained with a salt content of 0.6% w/v and beer volume of 700.0 ?L. The validated method showed limits of detection (LOD) in the range of 0.003?0.128 ?g L-1 and limits of quantification (LOQ) from 0.011 to 0.427 ?g L-1. Precision Coefficients of Variation values ranged from 3.0 to 18.7%, and recovery values of the analytes in beer varied between 80.1 and 100.3%. Among the PAHs derivatives evaluated in this study, only 9-fluorenone and 9-nitroanthracene were detected in some samples. Benzo[b]fluoranthene was the most detected analyte in the samples, and at least one PAH was detected in all samples. Principal component analysis (PCA) separated the samples into two groups, mainly due to the high relative concentrations of acenaphthene and chrysene. The cooling approach improved the extraction efficiency and the new system demonstrated high potential for portability and automation.

Automated summary

This study proposed a new cold fiber (CF-SPME) system using thermoelectric cooling to improve solid phase microextraction (SPME) efficiency.