1,720,985 research outputs found
Determination of aflatoxins in cereal flours by solid-phase microextraction coupled with liquid chromatography and post-column photochemical derivatization-fluorescence detection
No full textA new method for the determination of aflatoxins B1, B2, G1, and G2 (AFB1, AFB2, AFG1, AFG2) in cereal flours based on solid-phase microextraction (SPME) coupled with high performance liquid chromatography with post-column photochemical derivatization and fluorescence detection (SPME–HPLC–PD–FD) has been developed. Aflatoxins were extracted from cereal flour samples by a methanol:phosphate buffer (pH 5.8, I = 0.1) (80:20, v/v) solution, followed by a SPME step. Different SPME and HPLC–PD–FD parameters (fiber polarity, temperature, pH, ionic strength, adsorption and desorption time, mobile phase) have been investigated and optimized. This method, which was assessed for the analysis of different cereal flours, showed interesting results in terms of LOD (from 0.035 to 0.2 ng g−1), LOQ (from 0.1 to 0.63 ng g−1, respectively), within and inter-day repeatability (2.27% and 5.38%, respectively) linear ranges (up to 20 ng g−1 for AFB1 and AFG1 and 6ngg−1 for AFB2 and AFG2), and total raw extraction efficiency (in the range 55–59% at concentrations in the range 0.3–1 ng g−1 and 49–52% at concentrations in the range 1–10 ng g−1). The results were also compared with the purification step carried out by conventional immunoaffinity columns
Determinazione di aflatossine in campioni di cereali mediante SPME-HPLC e derivatizzazione fotochimica on-line post-colonna.
No full text¬Development of a mathematical model for online microextraction by packed sorbent under equilibrium conditions and its application for polycyclic aromatic hydrocarbons determination in water by gas chromatography-mass spectrometry
No full textDetermination of Aflatoxins in Cereal Samples by Solid–Phase Microextraction Coupled with Liquid Chromatography and Post-Column Photochemical Derivatization-Fluorescence Detection
No full textDevelopment of a mathematical model for online microextraction by packed sorbent under equilibrium conditions and its application for polycyclic aromatic hydrocarbon determination in water by gas chromatography–mass spectrometry
No full textDeterminazione di aflatossine in matrici alimentari mediante HPLC con derivatizzatore fotochimico post-colonna on-line e rivelazione fluorimetrica.
No full textDETERMINATION OF ALKYLPHENOLS IN RIVER WATER USING AN ETCHED STAINLESS STEEL WIRE - IONIC LIQUID - SOLID PHASE MICROEXTRACTION TECHNIQUE.
No full textAlkylphenols (APs) are ubiquitous environmental endocrine-disrupting chemicals (EDCs) arising from the degradation of alkylphenol polyethoxylates (APnEOs) in water systems. Emerging research suggests that Aps are widely distributed in various environmental matrices, and an increased awareness of their presence has led to an intensified interest in the trace analyses of these compounds . In this study, an etched stainless steel wire - ionic liquid (IL) - solid phase microextraction (SPME) device was developed for the direct extraction of four APs from water samples, namely 4-n-pentylphenol (4-NPP), 4-n-hexylphenol (4-NHP), p-tert-octylphenol (P-TOP) and nonylphenol (NP). The experimental data demonstrated that the etched stainless steel wire was a suitable substrate for IL-SPME, maintaining its high mechanical strength and, at the same time, a significant adsorption power toward ILs. The coating was prepared by direct deposition of the ILs onto the surface of the etched stainless steel wire, which exhibited a porous structure and a high surface area. Among the others ILs, 1-butyl-3-methylimidazolium hexafluorophosphate ([C8MIM][PF6]) exhibited maximum efficiency under the following experimental conditions: extraction time of 30 min, pH 2, sample temperature of 40 °C, and stirring. The IL coating exhibited an enrichment factor (EF) for the four APs, defined as the ratio between the concentration of the target compounds after and before the extraction, in the range 1382 – 4779. The detection limits (LOD, S/N = 3) ranged from 0.01 to 0.04 ng mL−1, and the RSD values for purified water spiked with APs ranged from 4.0 to 11.8% (n = 3). The calibration curves were linear in the range 0.5 - 200 ng mL−1 (R2 > 0.95). The optimized method was successfully applied for the analysis of real water samples
Effects of different surface treatments on ripening of Canestrato Pugliese cheese
No full textThe effect of different surface treatments (with olive oil, liquid smoke or pimaricin) on a number of physico-chemical characteristics (namely, moisture, NaCl content, pH, total and soluble nitrogen fractions, lipolytic processes and mould production) of the core and therind zones of Canestrato Pugliese cheese were studied during the whole ripening period (100 days). Treated cheese data were statistically compared with data obtained for untreated cheese. While for the core zone proteolytic and lipolytic processes, together with all the other physico-chemical properties studied, remained unaffected by the surface treatment, in the layer close to the rind these were influenced
significantly by the surface treatment in a manner correlated with the fungal growth
Microextraction by packed sorbent coupled with gas chromatography–mass spectrometry: A comparison between “draw-eject” and “extract-discard” methods under equilibrium conditions for the determination of polycyclic aromatic hydrocarbons in water
No full texttIn this work, two different extraction procedures for the analysis of different polycyclic aromatic hydro-carbons (PAHs) in water by microextraction by packed sorbent (MEPS) have been compared in terms ofsensitivity, reliability and time of analysis. The first method, called “draw-eject”, consists of a sequenceof cycles of aspirations and injections in the same vial; the second one, called “extract-discard”, consistsof a similar cycle sequence, but the aspired sample in this case is discarded into waste. The relevant par-tition equilibriums and extraction rates have been calculated by multivariate regression from the dataobtained after MEPS gas chromatography–mass spectrometry (MEPS-GC–MS) analysis of 16 PAHs fromwater samples. Partitioning parameters for a priori prediction of solute sorption equilibrium, recover-ies and preconcentration effects in aqueous and solvent systems have been calculated and comparedfor the two extraction procedures. Finally, real samples from sea, agricultural irrigation wells, streamsand tap water were analyzed. Detection (S/N ≥ 3) and quantification (S/N ≥ 10) limits were calculated forthe extraction processes. Under the experimental conditions used for the “draw-eject” procedure, thesevalues were in the range 0.5–2 ng L−1and 1.6–6.2 ng L−1, while for the “extract-discard” procedure theyranged from 0.2 to 0.8 ng L−1and from 0.8 to 2.0 ng L−1, respectively
Development and optimization of a HPLC method with on-line photochemical derivatization and fluorescence detection of aflatoxins in food matrices
No full textPresentazione oral
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