Solid-phase microextraction (SPME) is a rapid, easy and solvent-free or low-solvent consuming technique. Several kind of different fibers are available commercially, thus the most suitable selectivity may be chosen according to the specific application. In the present work, the potential of a particular and low exploited fiber (carbopack Z/PDMS) was investigated for determination of mineral oil (MO) and polycyclic aromatic hydrocarbons (PAHS) in foods. The prevalent sorption mechanism of the carbopack Z/PDMS fiber depends on the extraction conditions. In a non-polar solvent the effect of carbopack Z is predominant, which is particularly prone to the extraction of planar compounds by π- π interaction. While sampling the head-space (HS) the sorption mechanism of the PDMS predominates. Therefore, two independent approaches were studied, one using the direct-immersion (DI) extraction, the other by HS-SPME to exploit the carbopack Z and the PDMS selectivity, respectively.
A method to analyze parent PAHs was developed by direct immersion of the fiber in a hexane solution, following by GC-MS analysis for the determination of benzo[a]pyrene, or by comprehensive GC (GCxGC) coupled to time-of-flight (ToF) MS detector for the determination of the 16 PAHs highlighted by the European Union. Very good repeatability, limit of detection (LOD), and limit of quantification (LOQ) values were obtained.
The same fiber was employed to sampling the HS of food samples, thus exploiting, as prevalent sorption mechanism, the PDMS affinity. A good selectivity for MO components was observed, thus a rapid screening method was developed with satisfactory results.
