Use of triacylglycerol profiles established by high performance liquid chromatography with ultraviolet-visible detection to predict the botanical origin of vegetable oils.

A method for the determination of triacylglycerols (TAGs) in vegetable oils from different botanical origins by HPLC with UV-vis detection has been developed. Using a core-shell particle packed column (C18, 2.6 µm), TAG separation was optimized in terms of mobile phase composition and column temperature. Using isocratic elution with acetonitrile/n-pentanol at 10 °C, excellent efficiency with good resolution between most of the TAG peak pairs, within a total analysis time of 15 min, was achieved. Using mass spectrometry detection, a total of 15 peaks, which were common to oils of six different botanical origins (corn, extra virgin olive, grapeseed, hazelnut, peanut and soybean) were identified. These peaks were used to construct linear discriminant analysis (LDA) models for botanical origin prediction. Ratios of the peak areas selected by pairs were used as predictors. All the oils were correctly classified with assignment probabilities higher than 95%.

Ochratoxin A determination in ham by immunoaffinity clean-up and a quick fluorometric method.

A simple and rapid method for the determination of ochratoxin A (OA) in ham was developed using a basic methanolic extraction, immunoaffinity column clean-up and a fluorometric determination of the toxin contamination levels. A mean recovery of OA from ham samples spiked at levels from 0.7 to 9.7 microg kg(-1) was 83 +/- 6% using the fluorometric method, with a detection limit of 0.7 microg kg(-1). Recovery data were compared statistically with those obtained using reversed-phase high-performance liquid chromatography with acetonitrile-water-acetic acid (99:99:2) as mobile phase and fluorescence detection, commonly used for OA determination in food. A good correlation between the two analytical techniques was obtained. Both methods were successfully applied to 42 ham samples, 21 in the middle of the ripening period (after 6 months from the process beginning) and the other 21 at the end of the maturation, after 12 months. Twenty-seven samples (64%) showed an OA contamination level <1.0 microg kg(-1), the Italian Ministry of Health guideline. The maximum contamination level found was 2.3 microg kg(-1). A good agreement (R(2) = 0.980) between HPLC and fluorometer analysis on naturally contaminated samples was obtained.

New reversed-phase liquid chromatographic method to detect aflatoxins in food and feed with cyclodextrins as fluorescence enhancers added to the eluent.

The effect of succynil-beta-cyclodextrin (beta-CD-Su), dimethyl-beta-cyclodextrin (DIMEB) and beta-cyclodextrin (beta-CD) on the fluorescence of aflatoxins B1, B2, G1, G2 and M1 (AFB1, AFB2, AFG1, AFG2 and AFM1) was studied: beta-CD-Su promoted the largest fluorescence enhancement for AFB1 and AFM1 while DIMEB showed better results for AFG1 . On the basis of the fluorescence enhancement, a new RP-HPLC method for detecting aflatoxins B1, B2, G1, G2 and M1 was developed using cyclodextrins directly dissolved in the LC eluent. Aflatoxins B1, B2, G1 and G2 were resolved using a MICRA NPS ODS-1 column using methanol-water as mobile phase to which 6 x 10(-3) M beta-CD-Su or beta-CD were added. Chromatographic responses of AFB1 and AFG1 achieved using beta-CD dissolved in the mobile phase were enhanced, respectively, 8 and 12 times, and 10 and 15 times with beta-CD-Su. Detection limits lower than 0.3 microg/kg were achieved for all the four aflatoxins. Aflatoxin M1 was analysed using a Spherisorb S3 ODS-2 Narrow Bore column and methanol-water as mobile phase with added 2 x 10(-3) M beta-CD-Su. An area enhancement of 1.5 was detected for the toxin and the detection limit achieved under these analytical conditions was lower than 0.0005 microg/kg. Both methods were statistically validated showing a linear response for all the aflatoxins tested (R2 > or = 0.99), and applied to the analysis of spiked and naturally contaminated food samples.