Suchergebnisse

The aim of this study was to develop and validate an improved, simple, and sensitive method for the simultaneous determination of seven types (cadaverine, CAD ; hexylamine, HEX ; histamine, HIS ; phenylethylamine, PEA ; putrescine, PUT ; tyramine, TYR) of biogenic amines (BAs) in wine matrices. For this reason, a modified QuEChERS combined with ultra-performance liquid chromatography coupled to a triple quadrupole mass spectrometry (UHPLC-QqQ-MS/MS) method was investigated. The optimization of UHPLC-QqQ-MS/MS separation and QuEChERS procedure was performed. Under optimum conditions, the excellent chromatographic performance of the whole separation was accomplished within 6.3 min analyzing time. Meanwhile, the recoveries ranged from 77.2% to 101.7%, while relative standard deviation (RSD) remained between 0.0% and 9.4%. The limit of detection (LOD, 0.50&ndash ; 1.00 µ ; g/L) and the limit of quantification (LOQ, 1.65&ndash ; 3.30 µ ; g/L) were lower than those permitted by legislation in food matrices, which demonstrated the high sensitivity and applicability of this efficient method. This validated method was also applied in a pilot study to analyze BAs in 81 wine samples from Hexi Corridor Region (Gansu Province, Northwest China), CAD, HEX, HIS, PEA, PUT, and TYR were detected to varying degrees in the samples. However, when compared with the existing standards, the BAs in all 81 wine samples did not exceed the prescribed limit value or toxic dose (2&ndash ; 40 mg/L). Moreover, a statistical approach was also conducted using Pearson correlation analysis, and to evaluate their concentrations in terms of wine parameters (storage time, grape variety, wine type, and basic physicochemical index). The results showed that, among the seven kinds of BAs, the concentration of HIS had a certain correlation with alcoholic degree and grape variety. In addition, the level of PEA had a certain correlation with the wine pH and wine storage time. It is worth noting that this seems to be the first report regarding the application of QuEChERS-UHPLC-QqQ-MS/MS in the analysis of BAs in wine in this region.

The aim of this study was to develop and validate an improved, simple, and sensitive method for the simultaneous determination of seven types (cadaverine, CAD; hexylamine, HEX; histamine, HIS; phenylethylamine, PEA; putrescine, PUT; tyramine, TYR) of biogenic amines (BAs) in wine matrices. For this reason, a modified QuEChERS combined with ultra-performance liquid chromatography coupled to a triple quadrupole mass spectrometry (UHPLC-QqQ-MS/MS) method was investigated. The optimization of UHPLC-QqQ-MS/MS separation and QuEChERS procedure was performed. Under optimum conditions, the excellent chromatographic performance of the whole separation was accomplished within 6.3 min analyzing time. Meanwhile, the recoveries ranged from 77.2% to 101.7%, while relative standard deviation (RSD) remained between 0.0% and 9.4%. The limit of detection (LOD, 0.50–1.00 µg/L) and the limit of quantification (LOQ, 1.65–3.30 µg/L) were lower than those permitted by legislation in food matrices, which demonstrated the high sensitivity and applicability of this efficient method. This validated method was also applied in a pilot study to analyze BAs in 81 wine samples from Hexi Corridor Region (Gansu Province, Northwest China), CAD, HEX, HIS, PEA, PUT, and TYR were detected to varying degrees in the samples. However, when compared with the existing standards, the BAs in all 81 wine samples did not exceed the prescribed limit value or toxic dose (2–40 mg/L). Moreover, a statistical approach was also conducted using Pearson correlation analysis, and to evaluate their concentrations in terms of wine parameters (storage time, grape variety, wine type, and basic physicochemical index). The results showed that, among the seven kinds of BAs, the concentration of HIS had a certain correlation with alcoholic degree and grape variety. In addition, the level of PEA had a certain correlation with the wine pH and wine storage time. It is worth noting that this seems to be the first report regarding the application of QuEChERS-UHPLC-QqQ-MS/MS in ...

Grapevine cultivar and clone genotype is an important factor in the phenolic composition of wine. In this study, a new intense dark black berry color variant of Tempranillo, known as Tempranillo negro or VN21, is described. A targeted chromatographic approach based on UHPLC-QqQ-MS/MS was used to study the anthocyanins and noncolored phenols of the grape berry (skin and seeds) and wine. RJ43, one of the most cultivated clones in D.O.Ca. Rioja (Spain), was analyzed for comparison. Results suggest that the unique color of the grape skin in Tempranillo negro could be explained by higher concentrations of peonidin and cyanidin derivatives. This genotype accumulated anthocyanins in the seeds. Those differences in the berry were enhanced in the VN21 wines, which displayed notably higher concentrations of anthocyanins, and significantly increased contents of proanthocyanidins and stilbenes. This study exemplifies the application of phenol chromatographic analyses of spontaneous somatic variants to grapevine clonal selection. ; This study was financially supported by the Spanish Ministry of Economy and Competitiveness (co-funded by the European Social Fund, European Union) through the grant project BIO2017-86375-R; YF was supported by a grant from the Government of La Rioja; M.J. Motilva thanks the Consejo Superior de Investigaciones Científicas-CSIC for partial funding through the "Ayudas incorporación a escalas científicas CSIC, 2018" (Reference 201870I129).

Regulation (EC) n.1223/2009 of the European Parliament includes furocoumarins (FC) in the list of substances prohibited in cosmetic products except for normal content in natural essences used, the limit in sun protection and bronzing products is 1 mg/Kg [1]. Despite the official regulations the Scientific Committee on Consumers Products (ISCC) and the International Fragrance Association (IFRA) are still proposing the maximum content of psoralens in rinse-off and leave-on products, according to the latest evidences of phototoxicity [2,3]. To date, LC coupled to PDA detector is the main technique employed for FC determination. However, the high Limits of Quantification (LOQs) suggested by IFRA, limit the HPLC-PDA application to the analysis of essential oils, making necessary the development of a more sensitive HPLC-MS method for the analysis of FC at trace level in the finished cosmetic products [4]. This work provides a detailed analysis of PDA LOQs calculated for several oxygen heterocyclic compounds, among FC, coumarins, and polymethoxyflavones. The linear retention index approach was used, for the first time, together with the UV library, as an extra criterion for the reliable characterization of the target compounds in the essential oils. The LRI of specific volatile compounds were calculated in order to identify the interfering compounds of the matrix which affect the LOQs. Calibration curves were created in pure solvent and by adding the standard compounds to different blank samples, with the aim to overcome the matrix effect. Moreover, LRI was applied to a new more sensitive HPLC-QqQ MS method, with MS and MS/MS (Multiple Reaction Monitoring) libraries and external calibration. The MS method was validated and used to determine the content of FC in cosmetics, such as perfumes and body wash.

Trabajo presentado al 7th Worskhop CSIC-CNRS: "Micro- and Nano-Techniques for Analysis and Characterization of Proteins", celebrado en Madrid del 22 al 23 de julio de 2019. ; Casein and ovalbumin are used in the wine clarification process to promote interactions with undesirable compounds, such as polyphenols and tannins. This kind of proteins may trigger allergic reactions in susceptible individuals, therefore their presence in wines could became a human health risk, especially when not reported. For this reason, the European Union established that concentrations higher than 0.25 mg L-1 should be declared in the label. The objective of this work was to develop a tandem mass spectrometry method based on UHPLC coupled to quadrupole-time of flight tandem mass spectrometry (q-TOF-MS/MS) to accurately identify and quantify these allergenic proteins in Chilean wines. We focused our efforts on increasing the number of detectable peptides reported in literature in order to increase accuracy and reliability on the analysis. Triple quadrupole tandem mass spectrometry (QqQMS/SM) was also used to comparative evaluate the performance of q-TOF vs QqQ. Proteins were extracted combining the use of ultrafiltration membranes and precipitated with organic solvents. Then, proteins were digested with trypsin using ultrasounds energy. A face-centered central composite design with two central points was selected to optimize the enzymatic digestion, setting up a digestion time of 3 minutes and an enzyme/protein ratio of 1:10. Peptides separation was carried out on Phenomenex Kinetex XB Core-Shell C18 column (100 mm x 4.6 mm, 2.6 μm), at 35oC, using a mobile phase composed of ultrapure water and acetonitrile, both with 0.1 % (v/v) formic acid. MS analysis was carried out on an Agilent Q-TOF MS 6540 equipped with an orthogonal electrospray ionization (ESI) source (Agilent Jet Stream, AJS) and a Shimadzu (Kyoto, Japan) LC-MS-8030 triple quadrupole (TQ) mass spectrometer. Marker peptides for quantification were selected among the most abundant and stable. Quantification was performed in MRM mode, using an isotopically labeled peptide as internal standard. Q-TOF analysis based on full scan data and on product ion scan mode allowed the identification of a larger number of marker peptides than those reported for QQQ analysis. Thus, several precursor ion peptides for α-, β-casein and ovalbumin were identified, as well as characteristic peptides of k-casein that had not been previously reported in literature. LODs ranged from 4.7 to 8.5 μg L-1 working in MRM mode with QqQ; while slightly higher LODs (10-60 μg L-1) were obtained operating with q-TOF. The results show the advantage of using a q-TOF mass analyzer to detect and identify new marker peptides, while using QqQ for its exact quantification. Using the proposed methodology, some of the target peptides exhibited lower LODs than those reported in literature. Finally, sixty samples of Chilean wines were analyzed, finding 14 samples with higher levels of casein and ovalbumin than recommended by the International Organization of Vine and Wine. ; This study was funded by the National Fund for Scientific and Technological Development (FONDECYT) project No1171857 and by the Fund for Scientific and Technological Equipment (FONDEQUIP) project No 130209. G.A.R. would like to acknowledge MINECO for the "Juan de La Cierva-Formación" postdoctoral grant FJCI-2016-30902. ; Peer reviewed

AbstractWe investigate competition for order flow, market quality, and price discovery in the Nasdaq 100 Index Tracking Stock (QQQ). The QQQ, an AMEX‐listed, exchange‐traded fund, is the most actively traded security in the U.S. equities market. On July 31, 2001, the NYSE began trading the QQQ, marking the first time it traded securities of companies it does not list. The greatest volume of trading takes place on electronic communication networks (ECNs), following by trading on the AMEX and the NYSE. Most of the block trades are executed on the AMEX, where the bid‐ask spreads are narrower. We find that ECNs contribute the most to the price‐discovery process. The spreads on all trading platforms have decreased and market quality and price discovery have improved since QQQ shares have traded on the NYSE.

"Serial no. 97-QQQ." ; CIS Microfiche Accession Numbers: CIS 82 H161-55 ; Microfiche. ; Mode of access: Internet.

"Serial no. 93-QQQ." ; Hearings held March 21-Sept. 30, 1974, on H.R. 13267, 9468, 9054, 7954, 16857, and S. 3801. ; Mode of access: Internet.