Giorgia Purcaro

Overview on polycyclic aromatic hydrocarbons: Occurrence, legislation and innovative determination in foods

Polycyclic aromatic hydrocarbons are ubiquitous compounds, well-known to be carcinogenic, which can reach the food in different ways. Thus the analysis of such compounds has always been of great importance. The aim of the present review, is not only to give an overview of the most recent sample preparation and analytical approaches (such as pressurized liquid extraction, solid-phase microextraction, supercritical fluid extraction, etc.), but also to introduce such a topic to researchers who want to approach it for the first time; therefore, the most significant references related to general aspects, such as formation, toxicity, risk assessment, occurrence in food, are reported and briefly discussed.

Optimisation of microwave assisted extraction (MAE) for polycyclic aromatic hydrocarbon (PAH) determination in smoked meat.

A rapid extraction method involving microwave assisted extraction (MAE), followed by sample clean-up on a silica cartridge, reversed-phase high performance liquid chromatography (RP-HPLC) and spectrofluorimetric detection, was optimised for polycyclic aromatic hydrocarbon (PAH) determination in smoked meat. Compared to solvent extraction assisted by sonication, MAE, carried out with n-hexane on 2g of lyophilised sample at 115°C for 15min, allowed to obtain better extraction efficiencies. Limits of quantification (LOQ, s/n=10) lower than 0.2μg/kg wet weight were found for all PAHs, except for Fl (0.3μg/kg), P (0.6μg/kg) and IP (0.4μg/kg). The optimised procedure, that presented good analytical performances (with recoveries ranging from 77% to 103%, and precision within 10% for most of the PAHs), was applied to determine PAH content in different smoked meat products from the Italian market.

Evaluation of a rapid-scanning quadrupole mass spectrometer in an apolar × ionic-liquid comprehensive two-dimensional gas chromatography system.

Comprehensive two-dimensional gas chromatography (GC×GC) is a powerful technique which can enable a great increase in GC peak capacities. However, since secondary-column separations are very rapid, detectors with a fast acquisition rate are mandatory. Such a requirement has certainly limited the use of the quadrupole mass spectrometer in the GC×GC field. The present research is focused on the evaluation of a novel rapid-scanning quadrupole mass spectrometry (qMS) detector, characterized by a 20,000 amu/s scan speed and a 50 Hz scan frequency, using a 290 amu mass range (40-330 m/z). The performance of the MS system was assessed by analyzing mixtures of 24 allergens, as well as a perfume sample, through GC×GC/qMS. The MS parameters evaluated at different acquisition rates (50, 33, and 25 Hz), as well as in the (simultaneous) scan/selected ion monitoring (SIM) mode, were the number of data points per peak, mass spectrum quality, peak skewing, and sensitivity. Two GC×GC/qMS methods, using the 50 Hz acquisition rate and the scan/SIM mode, were validated. Both methods provided similar results in terms of repeatability, accuracy, and linearity, while a great increase in sensitivity was observed (ca. a factor of 10) under scan/SIM conditions. The validated method proved to be suitable for the analysis of perfume allergens, according to the requirements of Directive 2003/15/EC.

Determination of polycyclic aromatic hydrocarbons (PAHs) in commonly consumed Nigerian smoked/grilled fish and meat

Smoking and/or grilling, when carried out with traditional methods involving direct contact with wood combustion fumes, is responsible for high contamination levels with carcinogenic polycyclic aromatic hydrocarbons (PAHs). The aim of this work was to investigate the PAH content of different smoked or grilled meat and fish products commonly consumed in Nigeria. A rapid method involving microwave-assisted saponification and simultaneous extraction followed by solid-phase extraction (SPE), high-performance liquid chromatography (HPLC) separation and spectrofluorometric detection was employed. Samples that were smoked or grilled using traditional systems, which use a wood fire, were heavily contaminated with benzo[a]pyrene (BaP) at levels ranging from 2.4 to 31.2 µg kg−1 wet weight. Considerably lower contamination levels were found in samples smoked or grilled in the laboratory using a charcoal fire (BaP from 0.7 to 2.8 µg kg−1 wet weight). The health risk associated with a daily consumption of 100 g of these products was also evaluated using the margin of exposure (MOE) approach. MOE values lower than 10,000 were obtained for all smoked/grilled commercial samples, indicating a potential concern for consumer health.

Rapid SPE-HPLC determination of the 16 European priority polycyclic aromatic hydrocarbons in olive oils.

Polycyclic aromatic hydrocarbons (PAHs) are a large class of organic compounds. It has been established that the main source of exposure to these compounds for human beings is through food, particularly fats and oils, due to the lipophilic nature of these polycyclic compounds. The aim of this work was to optimise and validate a method involving SPE and HPLC for rapid determination of the 16 European Union (EU) priority PAHs (required by the Recommendation 2005/108/EC) in vegetable oils. Two spectrofluorometric detectors and a UV-Visible detector in series were used to identify and quantify the target compounds. Linearity, recoveries, LOD, and LOQ were found to be in agreement with the performance criteria for benzo[a]pyrene (BaP) analysis as required by the Commission Directive 2005/10/EC, and satisfactory for all the compounds of interest, except for cyclopenta[c,d]pyrene, which presented a very low signal in the UV. Optimised chromatographic conditions for the separation of 25 PAHs, comprising both EPA and EU priority PAHs plus benzo[e]pyrene and benzo[b]chrysene, have been also proposed.

Polycyclic aromatic hydrocarbons in frying oils and snacks.

The high incidence of lung cancer observed among Chinese women has been associated with exposure to fumes from cooking oil. Polycyclic aromatic hydrocarbons (PAHs) are a class of potentially mutagenic substances emitted from cooking oils heated at high temperatures. The objective of this study was to investigate whether deep frying with different oils under different conditions leads to the development of PAHs either in the oil or in the fried product (snacks). PAH analysis was carried out with solid-phase extraction followed by reverse-phase high-performance liquid chromatography and spectrofluorometric detection. Different oils were used to fry chips and extruded snacks in different industrial plants (continuous frying) at temperatures between 170 and 205 degrees C, and peanut oil was used to fry French fries and fish (discontinuous frying) at temperatures between 160 and 185 degrees C. No appreciable differences in PAH load was observed in the same oil before and after frying. Both before and after frying, the benzo[a]pyrene concentration in oils ranged from trace to 0.7 ppb. All the analyzed samples, including oils from fried snacks, had benzo[a]pyrene concentrations well below the 2 ppb limit recently proposed by the European Community.

Hyphenated liquid chromatography-gas chromatography technique: recent evolution and applications.

Liquid chromatography (LC) hyphenated with gas chromatography (GC) was first presented in 1979. Since then an intensive study has been carried out to explore different types of interfaces both for coupling normal-phase (NP) and reverse-phase (RP) LC with GC. The present review focuses on the technical progress and applications presented in the last decade, and it describes the most used interfaces. In fact, more flexible interfaces have been studied to improve the use of LC-GC, in particular the use of a programmed temperature vaporizer (PTV) injector. An intensive effort has also been devoted to optimizing the coupling of reverse-phase LC for analysis of water-based samples. A brief overview of comprehensive approaches (LC×GC) is discussed along with perspective for further improvement of the technique.

A rapid multidimensional liquid–gas chromatography method for the analysis of mineral oil saturated hydrocarbons in vegetable oils

The present paper describes an investigation directed toward the development of a rapid heart-cutting LC-GC method for the analysis of mineral oil saturated hydrocarbons contained in vegetable oils. The automated LC-GC experiments were carried out by using a system equipped with a syringe-type interface, capable of both heart-cutting and comprehensive (LC × GC) two-dimensional analysis. The first dimension separation was achieved on a 100 mm × 3 mm ID × 5 μm d(p) silica column, operated under isocratic conditions (hexane). A single 30-s cut, corresponding to a 175 μL volume, was transferred to a programmed temperature vaporizer. After the large volume injection, the target analytes were separated in a rapid manner (~9 min) using a 15 m × 0.1mm ID × 0.1 μm micro-bore GC capillary. The overall LC-GC run time enables the analysis of ca. 4 samples/hour. Quantification was performed by using external calibration, in the 1-200 mg/kg range. The method was validated in terms of linearity, precision, limits of detection and quantification, and accuracy. A series of commercial samples were subjected to analysis. Various degrees of contamination were found in all samples, in the 7.6-180.6 mg/kg range.

Characterization of bacterial lipid profiles by using rapid sample preparation and fast comprehensive two-dimensional gas chromatography in combination with mass spectrometry

The bacteria fatty acid profile has been extensively studied for taxonomic classification purposes, since bacteria, in general, contain particular and rare fatty acids, compared with animal and plant tissues. As for any real-world sample type, the development of rapid and reliable methods for (i) sample identification (in this case, bacterium type), and (ii) constituent identification (in this instance, the fatty acid profile) is desirable. In this research, a half-an-hour procedure, to analyze bacteria, was developed: a 2-min one-step sample preparation step was followed by a relatively fast comprehensive 2D GC-MS separation (25 min). Furthermore, dedicated MS libraries were constructed for the identification of bacteria and fatty acids. Finally, data processing, only qualitative at this stage, was carried out with the support of a novel comprehensive 2D GC software.

Enhanced resolution comprehensive two-dimensional gas chromatography applied to the analysis of roasted coffee volatiles.

The present research is based on the full exploitation of the separation power of a 0.05 mm internal diameter (ID) capillary, as a comprehensive two-dimensional (2D) GC (GC x GC) secondary column, with the objective of attaining very high-resolution second dimension separations. The aim was achieved by using a split-flow system developed in previous research [P.Q. Tranchida, A. Casilli, P. Dugo, G. Dugo, L. Mondello, Anal. Chem. 79 (2007) 2266], and a dual-oven GC x GC instrument. The column combination employed consisted of a polar 30 m x 0.25 mm ID column connected, by means of a T union, to a detector-linked high-resolution 1.1 m x 0.05 mm ID apolar analytical column and to a 0.33 m x 0.05 mm ID retention gap; the latter was connected to a manually operated split valve. As previously demonstrated, the use of a split valve enables the regulation of gas flows through both analytical columns, generating the most appropriate gas linear velocities. Comprehensive 2D GC experiments were carried out on Arabica roasted coffee volatiles (previously extracted by means of solid-phase microextraction) with the split-valve closed (equal to what can be defined as conventional GC x GC) and with the split-valve opened at various degrees. The reasons why it is absolutely not effective to use a 0.05 mm ID column as second dimension in a conventional GC x GC instrument will be discussed and demonstrated. On the contrary, the use of a 0.05 mm ID column as second dimension, under ideal conditions in a split-flow, twin-oven system, will also be illustrated and discussed.