1,721,134 research outputs found
Lab-on-a-Tip Based on a Bimetallic Nanoarchitecture Enabling Catalytic 4-Nitrophenol Switch-off
Full text linkMono-and multi-metal nanoparticles (MNPs), thanks to their unique and tunable features, still fascinate the analytical sciences, from their widespread use in sensing and biosensing as nanoplasmonic tags or catalysts up to MNPs-decorated surfaces. Here, a lab µ-Tip decorated with plasmonic-active polymeric films embodying gold/silver nanostructures is presented. The proposed lab-on-a-tip device speed-up the 4-nitrophenol conversion in 4-aminophenol, retaining the performances for more than 10 consecutive measures, acting as an enzyme-like catalyst
Biomonitoring data as a tool for assessing mycotoxins exposure of workers
Full text linkAflatoxins are toxic compounds naturally occurring in crops mainly produced by molds of the genus Aspergillus. They represent the most concerning class of agricultural contaminants with a focus on aflatoxin B1 (AFB1) since it can act as etiological agent for hepatocarcinogenesis and immunosuppression. The corresponding working protocols were focused on the quantification of AFB1 and its main metabolites in urine and serum samples of workers potentially exposed during their occupational hours in different industrial settings, namely corn-based feed production company. Biological samples of 61 workers (32 exposed and 29 control group) were collected over a week (Monday and Friday). In urine, only aflatoxin M1 (13% in exposed and 11% in control) was found; in serum, 6.1% of samples revealed AFB1 presence (9,7% in exposed and 1.9% in control). However, neither difference between the average levels of exposed and control groups nor difference between levels of Friday and Monday deliveries were found. Ochratoxin A (OTA) was also tested and found in all serum samples with 33% of the samples having a concentration higher than the limit of quantification (LOQ) and the remaining between the limit of detection (LOD) and LOQ. Moreover, for OTA, a good correlation was found between Friday and Monday OTA levels
GC-MS aroma characterization of coffee and vegetable matrices: focus on 3-Alkyl-2-Methoxypyrazines
No full textMETAL NANOPARTICLES-BASED PLASMONIC ASSAYS: AN EMERGING ANALYTICAL TOOL FOR FOOD ANALYSIS
No full textAnalysis of Bile Acids Profile in Human Serum by Ultrafiltration Clean-up and LC-MS/MS
No full textBile acids (BAs) are useful biomarkers for the diagnosis of many diseases. The pathologies related to bile acid synthesis are often expressed in the first years of life and may lead to serious liver injury. Here we present a sensitive and rapid method for the analysis of the main 14 bile acids in human serum by liquid chromatography-tandem mass spectrometry. The chromatographic separation is performed using a core-shell column which provides improved separation, highly desirable considering the small structural differences among the analytes. All isomeric BAs of interest were resolved in less than 9 min. Sample pretreatment consisted in ultrafiltration of serum after addition of methanol by means of centrifugal filter devices. The calculated LOQs ranged between 2 and 5 ng mL(-1) with linearity of the calibration curves in the 5-5,000 ng mL(-1) range for all the BAs. The extraction recoveries for all the analytes were higher than 80 %. Intra-day and inter-day coefficients of variation were all below 15 %. The method proposed has been validated and has been applied for the analysis of serum of pediatric patients. This simple procedure allowed minimal consumption of serum sample (about 100 mu L) and a rapid assay, easily implementable in routine analysis
Peptides trapping cocaine: docking simulation and experimental screening by solid phase extraction followed by liquid chromatography mass spectrometry in plasma samples
No full textTwo different hexapeptides were computationally designed and tested as selective SPE sorbent for cocaine. The amino acid residues used for designing the two hexapeptides, tested in SPE experiments, were, according to chemical function and interatomic distances, the most (QHWWDW) and the lowest (ESSIDH) preserved sequences in 4 proteins binding cocaine. The hexapeptide-cocaine complex was docked with different scoring functions combinations and resulting binding scores were compared with the SPE results. The extraction procedure for SPE was optimized considering volume loading, pH effect, and human plasma matrix interferences. Cocaine was loaded onto the modified resin cartridge at 10 ng mL(-1) and the peptide QHWWDW was found to have the highest recovery with the best retention at pH 7.5, in agreement with docking simulation. Retention experiments were carried out also on cocaine metabolites nor-cocaine, benzoylecgonine and ecgonine methyl ester. Except for nor-cocaine the retention of metabolites on resin modified with peptide QHWWDW decreased drastically confirming the peptide selectivity, and validating the simulation data. Compared to standard solutions, only a slight decrease in cocaine recovery was observed loading human plasma samples after a partial protein precipitation. (C) 2013 Elsevier B.V. All rights reserved
Phenol Profiling and Nutraceutical Potential of Lycium spp. Leaf Extracts Obtained with Ultrasound and Microwave Assisted Techniques
No full textIn recent years, agricultural and industrial residues have attracted a lot of interest in the recovery of phytochemicals used in the food, pharmaceutical, and cosmetic industries. In this paper, a study on the recovery of phenol compounds from Lycium spp. leaves is presented. Ultrasound-assisted extraction (UAE) and microwave-assisted extraction (MAE) have been used with alcoholic and hydroalcoholic solvents. Methanolic UAE was the most successful technique for extracting phenols from Lycium leaves, and we used on leaves from L. barbarum and L. chinense cultivated in Italy. The extracts were then characterized as regards to the antioxidant properties by in vitro assays and the phenol profiling by a high performance liquid chromatography-diode array detector (HPLC-DAD). Chlorogenic acid and rutin were the main phenol compounds, but considerable differences have been observed between the samples of the two Lycium species. For example, cryptochlorogenic acid was found only in L. barbarum samples, while quercetin-3-O-rutinoside-7-O-glucoside and quercetin-3-O-sophoroside-7-O-rhamnoside only in L. chinense leaves. Finally, multivariate statistical analysis techniques applied to the phenol content allowed us to differentiate samples from different Lycium spp. The results of this study confirm that the extraction is a crucial step in the analytical procedure and show that Lycium leaves represent an interesting source of antioxidant compounds, with potential use in the nutraceutical field
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