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The marine dinojlagellates Prorocentrum micans, Gonyaulax polyedra, Gymnodinium sp., and Alexandrium tamarense, collected from the Adriatic Sea during red-tide blooms, were cultured to investigate the 4-methy l sterol constituents. To ascertain a possible influence of cell age on the 4-methyl sterol content, for one strain (Gymnodinium sp.) we investigated the composition of these constituents at exponential and stationaly growing phases. The lipid material extracted with acetone from the lyophilized algal samples was fractionated by thin-layer chre matography. The 4-methyl sterols recovered from the layer were converted into the corresponding OTMS derivatives. Nine of 11 constituents were identified by gas chromatography and gas chromatography-mass spectromet?y; only two minor constituents were characterized by their gas chromatographic parameters. All free methyl sterols identzjied in the algal samples had been detected previously in various dinoflagellates. The 4-methyl sterol fractions generally

High-performance liquid chromatography with fluorescence detection was used for the analysis of polycyclic aromatic hydrocarbons (PAHs), in "Diavoletto" smoked cheese. Such cheese is typically produced in the Sorrento peninsula, and it is smoked commonly with different materials of vegetable origin. The importance of the smoking generation material is proven by the attention that the EU is paying in indicating the list of wood that may be used to produce smoking flavor agents. The PAHs considered are classified as "probable human carcinogens" by the U.S. Environmental Protection Agency for sufficient data from animal bioassays. The smoked samples contained high molecular mass PAHs with different levels ranging from 0.12 to 6.21 microg/kg. The determination was carried out also on liquid smoking flavor agents, smoke-flavored cheese, and nonsmoked cheese to measure the level of contamination before the treatment.

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a b s t r a c tThe aim of this study was to determine the presence and the level of contamination of the most important mycotoxins (deoxynivalenol, fumonisin B 1 and B 2 , aflatoxin B 1 , B 2 , G 1 and G 2 , ochratoxin A and zearalenone) in 48 samples of extruded dry dog food found in the Italian market (24 samples from standard economy lines, 24 of premium lines). Analyses were performed using ultra-performance liquid chromatography coupled to tandem mass spectrometry. Although the concentrations of the mycotoxins in all samples proved to respect the European legislation with regards to animal feed, the analyses revealed a substantial presence of deoxynivalenol, fumonisins and ochratoxin A, with values above the limit of quantification (5 g/kg) in 100%, 88% and 81% of the samples, respectively. In contrast, aflatoxins and zearalenone contamination proved to be very modest, with 88% and 75% of the samples, respectively, showing concentrations below the corresponding limit of quantification (5 g/kg for aflatoxins and 10 g/kg for zearalenone). Moreover, despite a very heterogeneous contamination, the concentration of fumonisins and ochratoxin A was significantly higher in standard foods than in premiumones (491 vs. 80.2 g/kg dry matter for fumonisin B 1 ; 113 vs. 38.5 g/kg dry matter for fumonisin B 2 ; 599 vs. 103 g/kg dry matter for total fumonisins; 23.8 vs. 13.0 g/kg dry matter for ochratoxin A; P<0.001). Furthermore, a simultaneous presence of different mycotoxins (at concentrations higher than their limit of quantification) was observed in most of the pet foods analyzed; in particular, 19% of the samples were contaminated by no fewer than two different types of mycotoxins, 52% by three, 25% by four and 2% by all the mycotoxins evaluated. These results revealed the need for further investigation into the potential risk deriving from chronic exposure to low doses of the different types of mycotoxins that pet species are subject to today.