Determination of aflatoxins in cereal flours by solid-phase microextraction coupled with liquid chromatography and post-column photochemical derivatization-fluorescence detection

A 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

DETERMINATION OF ALKYLPHENOLS IN RIVER WATER USING AN ETCHED STAINLESS STEEL WIRE - IONIC LIQUID - SOLID PHASE MICROEXTRACTION TECHNIQUE.

Alkylphenols (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

REDUCING THE PHTHALATES CONTAMINATION DURING THE ANALYSIS PROCESS USING GAS PURGE MICROSYRINGE EXTRACTION.

Phthalate esters (PAEs) are commonly used as non-reactive plasticizers in vinyl plastics to increase the flexibility of plastic polymers . Numerous studies reported about the PAEs as a class of endocrine-disrupting chemicals . In addition, these studies also showed that a major source of human exposure to phthalates is the diet . To date, the largest problem in PAEs analysis is the contamination due to the wide and uncontrolled PAE presence in the environment, including chemicals and glassware: sample contamination may then occur in every step of the analysis process. To reduce the possibility of contamination during sample handling, it is then necessary to shorten the pretreatment step, and to keep the analysis procedure as simple as possible. Gas purge microsyringe extraction (GP-MSE) is a fast technique, suitable for miniaturization, with no plastic components in the whole device that works under a nitrogen flow, and it can be considered a good candidate to reach this goal. In fact, with GP-MSE a new and low-blank-value analytical method for the analysis of PAEs in foodstuffs was set-up. The overall recoveries ranged from 85.7 to 102.6%, and the RSD was less than 10%. This method has been applied in the monitoring of PAEs in 78 foodstuffs. The results showed that a wide variety of PAE concentrations were found in the different groups, and the highest content of PAEs (in the range 658 - 1610 ng g-1 fresh weight) was found in seafood. The concentration values found in food were in the following order: DEHP > DBP > DEP ≈ DMP > BBP ≈ DNOP. Finally, the daily intake of PAEs was estimated for adults based on the levels of PAEs in foodstuffs. The total estimated daily intakes of PAEs, calculated in terms of DEHP amount, ranged from 3.2 and 12.9 mg kg-1 bw d-1

An electrophoretic approach to reveal the freshness of buffalo mozzarella cheese

Freshness is one of the more appreciated attributes for high moisture buffalo mozzarella cheese (BMC) that guarantees highest quality for the consumer. However, freshness decreases during shelflife of this cheese due to proteolysis events caused mainly by milk endogenous enzymes, such as plasmin. Plasmin generated g-casein (g-CN) fragments from b-CN proteolysis can be assessed by SDS-PAGE and image analysis; b-CN decrease and g-CN increase represent useful markers to obtain an index of freshness (F). For this purpose, a “Control Line” was assessed analysing BMC with PDO certification. Samples were stored under different conditions (room temperature, refrigerated and frozen) for different times. Moreover, 145 BMC samples purchased from markets were studied to understand if the calculated F was consistent with the Control Line study results. Assessing the proteolysis mechanism for formation of g- CN fragments provides a reliable method to evaluate freshness of PDO BMC during storage of this typical Italian product

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

tIn 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

Milk Authenticity By Ion-Trap Proteomics Following Multi-Enzyme Digestion

The practice of adding adulterating substances (water, starch, sodium citrate, urea, sucrose, melamine, etc) in milk products in order to raise profits is worldwide employed. In addition, higher priced milk, coming from minor dairy species, such as goat and buffalo showing high nutritional and economical value, is often illegally integrated with the lower priced cow milk. The presence of species-specific proteins, different from those declared in label, may be a serious problem for people with allergies. The development of proper analytical methods is therefore essential to protect consumer benefits and product authenticity, as well as to detect economic frauds. Several analytical techniques, including capillary electrophoresis1, polymerase chain reaction2