Determination of polycyclic aromatic hydrocarbons in distilled beverages using HPLC-DAD as a proof of concept for dispersive droplet extraction and in situ formation of magnetic ionic liquids.

Abstract

Polycyclic aromatic hydrocarbons (PAHs) are a class of compounds known for their genotoxic and carcinogenic effects. They can be formed by the pyrolysis of organic matter and can be present in several matrices, including distilled beverages. Since these samples also contain different interferents and low concentrations of these analytes, it is important that a sample preparation step be performed prior to analysis. Although many methods have been reported for the analysis of these analytes, only a few have explored alternative procedures and extraction materials, such as the use of magnetic ionic liquids (MILs) and microextraction approaches. The development of alternative extraction techniques can improve analytical figures of merit and sample throughput, while also enhancing analyst safety. In this work, two in situ formed MILs, [Co(C₄IM)₄][NTf₂]₂ and [Ni(C₄IM)₄][NTf₂]₂, were employed as extraction phases for the high-throughput parallel dispersive droplet extraction (Pa-DDE) of PAHs in distilled beverages such as cachaça and rum. In this approach, a 96-well plate system with magnets was used to collect the MIL formed during the extraction. This permitted up to 96 samples to be processed simultaneously, resulting in sample preparation times of less than 1 minute per sample when using the optimized procedure. Besides extraction time, the type and amount of MILs were evaluated and optimum conditions were obtained using 10 mg of [Co(C₄IM)₄]Cl₂. Limits of detection (LOD) and quantification (LOQ) ranged from 0.3 to 7.5 μg L^-1 and 1 to 25 μg L^-1, respectively. All values for determination coefficients were higher than 0.991 and were considered adequate. The values of intraday and interday precision were all lower than 20.8 and 26.2%, respectively. Finally, accuracy was evaluated after relative recovery studies performed with 5 samples and varied from 52.1 to 150.1%. Samples used for this study were evaluated and none of the analytes were detected. This work represents a new application of in situ formed MILs for the analysis of more complex samples, since most of the previous studies using this extraction phase were evaluated in water samples.