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Determination of phenolic compounds in honey using dispersive liquid-liquid microextraction.

Honey is a valuable functional food rich in phenolic compounds with a broad spectrum of biological activities. Analysis of the phenolic compounds in honey is a very promising tool for the quality control, the authentication and characterization of botanical origin, and the nutraceutical research. This work describes a novel approach for the rapid analysis of five phenolic acids and 10 flavonoids in honey. Phenolic compounds were rapidly extracted and concentrated from diluted honey by dispersive liquid-liquid microextraction (DLLME) and then analyzed using high performance liquid chromatography with UV absorbance detection (HPLC-UV). Some important parameters, such as the nature and volume of extraction and dispersive solvents, pH and salt effect were carefully investigated and optimized to achieve the best extraction efficiency. Under the optimal conditions, an exhaustive extraction for twelve of the investigated analytes (recoveries >70%), with a precision (RSD<10%) highly acceptable for complex matrices, and detection and quantification limits at ppb levels (1.4-12 and 4.7-40ngg(-1), respectively) were attained. The proposed method, compared with the most widely used method in the analysis of phenolic compounds in honey, provided similar or higher extraction efficiency, except in the case of the most hydrophilic phenolic acids. The capability of DLLME to the extraction of other honey phytochemicals, such as abscisic acid, was also demonstrated. The main advantages of developed method are the simplicity of operation, the rapidity to achieve a very high sample throughput and low cost.

Development and validation of a method for the determination of (E)-resveratrol and related phenolic compounds in beverages using molecularly imprinted solid phase extraction.

A molecularly imprinted polymer was prepared using (E)-resveratrol as template and was evaluated for multicomponent multiclass analysis of polyphenolic compounds in complex matrices such as natural and alcoholic beverages. Chromatographic evaluation of the polymer exhibited high selectivity for (E)-resveratrol and its structural analogues, quercetin, and other flavonoids. An analytical procedure based on molecularly imprinted solid phase extraction (MISPE) and high-performance liquid chromatography coupled to UV detector was developed and validated for determination of (E)-resveratrol and quercetin in wine and fruit juice samples. The specific binding capacity of the MIP was estimated as 80 μg g(-1) polymer by the cartridge test. MISPE sample pretreatment allows an excellent sample cleanup, enormously decreasing the number of coextracted potentially interfering compounds. Under the described conditions, by extracting 2 mL samples a clean extract is obtained and (E)-resveratrol and quercetin could be easily identified at concentration levels of, respectively, 1.5 and 7.0 μg L(-1).

Rapid and automated analysis of aflatoxin M1 in milk and dairy products by online solid phase extraction coupled to ultra-high-pressure-liquid-chromatography tandem mass spectrometry.

This study reports a fast and automated analytical procedure for the analysis of aflatoxin M1 (AFM1) in milk and dairy products. The method is based on the simultaneous protein precipitation and AFM1 extraction, by salt-induced liquid-liquid extraction (SI-LLE), followed by an online solid-phase extraction (online SPE) coupled to ultra-high-pressure-liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) analysis to the automatic pre-concentration, clean up and sensitive and selective determination of AFM1. The main parameters affecting the extraction efficiency and accuracy of the analytical method were studied in detail. In the optimal conditions, acetonitrile and NaCl were used as extraction/denaturant solvent and salting-out agent in SI-LLE, respectively. After centrifugation, the organic phase (acetonitrile) was diluted with water (1:9 v/v) and purified (1mL) by online C18 cartridge coupled with an UHPLC column. Finally, selected reaction monitoring (SRM) acquisition mode was applied to the detection of AFM1. Validation studies were carried out on different dairy products (whole and skimmed cow milk, yogurt, goat milk, and powder infant formula), providing method quantification limits about 25 times lower than AFM1 maximum levels permitted by EU regulation 1881/2006 in milk and dairy products for direct human consumption. Recoveries (86-102%) and repeatability (RSD<3, n=6) meet the performance criteria required by EU regulation N. 401/2006 for the determination of the levels of mycotoxins in foodstuffs. Moreover, no matrix effects were observed in the different milk and dairy products studied. The proposed method improves the performance of AFM1 analysis in milk samples as AFM1 determination is performed with a degree of accuracy higher than the conventional methods. Other advantages are the reduction of sample preparation procedure, time and cost of the analysis, enabling high sample throughput that meet the current concerns of food safety and the public health protection.

HRMS Profile of a Hazelnut Skin Proanthocyanidin-rich Fraction with Antioxidant and Anti-Candida albicans Activities.

Roasted hazelnut skins (RHS) represent a byproduct of kernel industrial processing. In this research, a RHS extract (RHS-M) and its fraction RHS-M-F3 enriched in proanthocyanidins (PAs), with antioxidant activity, were characterized in terms of total phenolic compound and PA contents. RHS-M and RHS-M-F3 showed antifungal properties against Candida albicans SC5314 (MIC2 = 3.00 and 0.10 μg/mL and MIC0 = 5.00 and 0.50 μg/mL, respectively), determined by the microbroth dilution method and Candida albicans morphological analysis. No cytotoxic effect on HEKa and HDFa cell lines was exhibited by RHS-M and RHS-M-F3. The metabolite profiling of RHS-M and RHS-M-F3 was performed by thiolysis followed by HPLC-UV-HRMS analysis and a combination of HRMS-FIA and HPLC-HRMS(n). Extract and fraction contain oligomeric PAs (mDP of 7.3 and 6.0, respectively, and DP up to 10) mainly constituted by B-type oligomers of (epi)-catechin. Also, (epi)-gallocatechin and gallate derivatives were identified as monomer units, and A-type PAs were detected as minor compounds.

Chemical profile and cellular antioxidant activity of artichoke by-products

Artichoke by-products, produced from agricultural procedures and the processing industry, represent a huge amount of discarded material. In this research, the main artichoke by-products, bracts and leaves, were characterized in terms of their bioactive constituents (phenolic compounds and inulin) and cellular antioxidant potential to estimate their nutraceutical potential. The ultrahigh-performance-ultraviolet detection-high resolution mass spectroscopy (UHPLC-UV-HRMS) profiles of both by-products show that 5-caffeoylquinic acid and 1,5-dicaffeoylquinic acid are the most abundant bioactive compounds, and the content of flavone glycosides can be used to discriminate between bracts and leaves. Artichoke by-products contain a remarkable overall phenolic content (0.5-1.7 g per 100 g dry matter), whereas they differ widely in the amounts of inulin with higher levels in bracts (3.8-8.2 g per 100 g dry matter). The cellular antioxidant activities of bract and leaf extracts (half maximal effective concentration (EC50) = 26.6-124.1 mg L-1) are better than or similar to that of a commercial leaf extract, and are related to the dicaffeoylquinic acid levels, particularly to 1,5-dicaffeoylquinic acid. These results reveal that artichoke by-products are a promising and cheap source of bioactive compounds. Bracts could be used as a source of inulin and caffeoylquinic acids for the production of food additives and nutraceuticals and also as an alternative to the traditional application of leaf extracts.

Rapid and automated on-line solid phase extraction HPLC–MS/MS with peak focusing for the determination of ochratoxin A in wine samples

This study reports a fast and automated analytical procedure based on an on-line SPE-HPLC-MS/MS method for the automatic pre-concentration, clean up and sensitive determination of OTA in wine. The amount of OTA contained in 100μL of sample (pH≅5.5) was retained and concentrated on an Oasis MAX SPE cartridge. After a washing step to remove matrix interferents, the analyte was eluted in back-flush mode and the eluent from the SPE column was diluted through a mixing Tee, using an aqueous solution before the chromatographic separation achieved on a monolithic column. The developed method has been validated according to EU regulation N. 519/2014 and applied for the analysis of 41 red and 17 white wines. The developed method features minimal sample handling, low solvent consumption, high sample throughput, low analysis cost and provides an accurate and highly selective results.

Oil distillation wastewaters from aromatic herbs as new natural source of antioxidant compounds

Distillation wastewaters (DWWs) are generated during the essential oil steam distillation from aromatic herbs. Despite of growing interest on novel source of natural antioxidant compounds as food additives, studies on DWWs are scarse. Herein, the potential of DWWs produced by the distillation of packaged fresh basil, rosemary and sage wastes was evaluated by chemical and antioxidant characterization. HPLC-DAD-HRMS profiling revealed that DWWs contain water-soluble phenolic compounds, mainly caffeic acid derivatives and flavonoid glycosides, with rosmarinic acid (RA) as predominant components (29-135mg/100mL). DWWs demonstrated high levels of total phenolic compounds (TPC, 152-443mg GAE/100mL) and strong antioxidant capacities, in ORAC, DPPH and ABTS assays (1101-4720, 635-4244 and 571-3145μmol TE/100mL, respectively). Highly significant correlations of TEAC values with TPC and RA contents revealed that phenolic compounds and high RA content were responsible of DWWs antioxidant properties.Thus, DWWs are proposed as a new promising source of natural food additives and/or functional ingredients for cosmetic, nutraceutical and food applications.

Occurrence of aflatoxin M1 in milk samples from Italy analysed by online-SPE UHPLC-MS/MS

Abstract The occurrence of aflatoxin M1 in 69 milk samples collected in a south region of Italy in 2016 was evaluated. The samples were analysed using an automated method based on online SPE coupled with UHPLC tandem mass spectrometry. After a salt induced liquid–liquid extraction with acetonitrile to remove protein from milk, the extract was diluted with water and analysed using an automated online SPE MS/MS method. Among the analysed samples no one had AFM1 higher than the legally allowable limits whereas 71.4% of the other analysed samples were above the LOD of the method. The highest contamination level of AFM1 was found in pasteurised milk (44.39 ng kg−1). The results show the worrying and widespread of AFM1 contamination, highlighting the necessity of monitoring studies in order to evaluate the reduction of the maximum legal limit.

Characterisation of nutraceutical compounds from different parts of particular species of Citrus sinensis ‘Ovale Calabrese’ by UHPLC-UV-ESI-HRMS

Abstract Consumers are aware of diet causing health problems and therefore there is an increased demand for natural ingredients that are expected to be safe and health-promoting. Many of these compounds belong to the class of flavonoids and can be divided into these five groups: flavanones, flavones, flavonols, flavanols, isoflavones and anthocyanidins. Extracts from citrus fruits are usually used as functional ingredients for several products. The aim of this paper was to develop an UHPLC-UV-ESI-HRMS method to define the metabolite profile of different parts of citrus fruit, of a particular cultivar called ‘Ovale Calabrese’, and in its main by-products. The high resolution mass spectrometry analysis allowed the identification of 27 compounds belonging to the classes of flavonoids and terpenoids. The high contents of phytochemical compounds, reveal the potential use of the ‘Ovale Calabrese’ as a rich source of nutraceutical compounds.

Ultrasound assisted dispersive liquid-liquid microextraction for fast and accurate analysis of chloramphenicol in honey

Honey is a food produced from honey bee widely used for the sweetening power and for its biological properties. In order to prevent the infection of the hive, different xenobiotics (antibiotics, pesticide) were frequently employed. One of these substances is the chloramphenicol, that given its chemical stability could often found in food. Chloramphenicol have several side effects in humans after their ingestion and for this reason their intake must be avoid. The aim of this study, was developed an ultrasound-assisted dispersive liquid-liquid microextraction method coupled with UHPLC MS/MS determination, for fast and accurate analysis of chloramphenicol in honey. The parameters affecting on extraction efficiency were carefully optimized using an experimental design in order to maximized the recovery reducing matrix effects. After the optimization the method was validated and successfully applied to 66 honey samples.