Search results for "Tandem"
showing 10 items of 560 documents
Energy loss and straggling of MeV Si ions in gases
2017
We present measurements of energy loss and straggling of Si ions in gases. An energy range from 0.5 to 12 MeV/u was covered using the 6 MV EN tandem accelerator at ETH Zurich, Switzerland, and the K130 cyclotron accelerator facility at the University of Jyväskylä, Finland. Our energy-loss data compare well with calculation based on the SRIM and PASS code. The new straggling measurements support a pronounced peak in He gas at around 4 MeV/u predicted by recent theoretical calculations. The straggling curve structure in the other gases (N2, Ne, Ar, Kr) is relatively flat in the covered energy range. Although there is a general agreement between the straggling data and the theoretical calculat…
ChemInform Abstract: Asymmetric Tandem Reactions: New Synthetic Strategies
2010
The use of domino and multicomponent reactions in asymmetric synthesis is con- stantly increasing nowadays. This allows for the synthesis of complex molecules in a single synthetic sequence, usually with high atom economy. Herein, we report three examples of new asymmetric tandem reactions recently developed in our laboratories, giving rise to new families of enantiomerically enriched fluorinated and nonfluorinated heterocycles. Thus, 1,4-dihydropyridines (1,4-DHPs) bearing fluorinated substituents at C6 were assembled by means of a Hantzsch-type reaction; cyclic β-amino carbonyl derivatives were prepared using a cross-metathesis (CM)-intramolecular aza-Michael sequence; while fluorinated i…
Untargeted metabolomics of fresh and heat treatment Tiger nut ( Cyperus esculentus L. ) milks reveals further insight into food quality and nutrition
2017
Tiger nut (Cyperus esculentus L.) is a crop traditionally grown in Valencia Region (Spain) and other temperate and tropical regions in the world, where its tubers are commonly consumed as tiger nut milk (horchata). Because of their nutritive potential and original taste, these products are beginning to spread internationally and, as consequence, analytical procedures to assess nutritional profiles, quality control issues are acquiring increasing relevance. The main objective of this study was to use an advance analytical method and chemometrics tools to determine if the ultra-high temperature (UHT) treatment necessary to extend the shelf life of tiger nut milk would affect the profile of nu…
Impact of glucuronide interferences on therapeutic drug monitoring of posaconazole by tandem mass spectrometry.
2010
Abstract Background: Posaconazole is a novel antifungal drug for oral application intended especially for therapy of invasive mycoses. Due to variable gastrointestinal absorption, adverse side effects, and suspected drug-drug interactions, therapeutic drug monitoring (TDM) of posaconazole is recommended. Method: A fast ultra performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for quantification of posaconazole with a run-time <3 min was developed and compared to a LC-MS/MS method and HPLC method with fluorescence detection. Results: During evaluation of UPLC-MS/MS, two earlier eluting peaks were observed in the MRM trace of posaconazole. This was only seen in p…
Ochratoxin A levels in the plasma of healthy blood donors from Valencia and estimation of exposure degree: comparison with previous national Spanish …
2010
Blood plasma levels of ochratoxin A, a toxic secondary metabolite of several fungal species belonging to the genera Aspergillus and Penicillium, were determined in 168 blood donors from the population of Valencia (Spain) using LC-FLD. In conjunction with blood collection, detailed information on diet was obtained by using a questionnaire that encompassed a wide range of products potentially contaminated with the toxin. The investigation revealed a detection frequency of 100%. Mean level was 1.09 microg OTA/l of plasma and concentrations ranged between 0.15 and 5.71 microg OTA/l of plasma. Men's levels were slightly higher than levels observed in women. Results were analysed by Spearman rank…
Multi-mycotoxin contamination of green tea infusion and dietary exposure assessment in Moroccan population
2021
Green tea infusion is one of the most widely drunk beverages worldwide due to its health benefits associated with microelements, essential oils, and polyphenols, etc. Several studies have reported that green tea is subjected to contamination by various toxigenic fungi. Thus, this work aims to investigate the co-occurrence of 15 mycotoxins [four aflatoxins (AFB1, AFB2, AFG1, AFG2), ochratoxin A (OTA), beauvericin (BEA), four enniatins (ENA, ENA1, ENB, ENB1), zearalenone (ZEN), alternariol (AOH), tentoxin (TENT), T-2 and HT-2 toxins] in green tea samples available in Morocco by liquid chromatography tandem mass spectrometry method. Analytical and consumption data were then used to assess the …
Bioaccessibility of Deoxynivalenol and its natural co-occurrence with Ochratoxin A and Aflatoxin B1 in Italian commercial pasta
2012
Abstract Cereals products for direct human consumption are rarely contaminated by moulds, unlike raw materials, which are often infected, either in the field or during storage. In this study, 27 samples of dried pasta characterised by size, packaging and marketing intended for young children consumption were collected and analysed by liquid chromatography (LC) and liquid chromatography–tandem mass spectrometry (LC–MS/MS) for Deoxynivalenol (DON), Ochratoxin A (OTA) and Aflatoxin B 1 (AFB 1 ) determination. The samples that showed the highest amounts of one of the mycotoxins were cooked for 10 min, digested with an in vitro gastrointestinal protocol and bioaccessibility values were calculate…
Evaluation of matrix solid-phase dispersion (MSPD) extraction for multi-mycotoxin determination in different flours using LC-MS/MS
2011
An existing matrix solid-phase dispersion (MSPD) method for aflatoxins (AFs) and ochratoxin A (OTA) extraction was extended by further 14 mycotoxins. After it careful optimization, this method was applied to determine the occurrence of these mycotoxins on commercial flour samples (with different cereals composition) collected from local markets. In a total of 49 samples investigated, 9 mycotoxins were identified. Nivalenol (NIV) and Beauvericin (BEA) were the mycotoxins found most frequently. The samples that presented major contamination were wheat flours and bakery preparations. Despite of the great number of positives finding, only one wheat flour sample exceeded the maximum limits (ML) …
Mycotoxins in herbal teas marketed in Latvia and dietary exposure assessment
2019
The occurrence of 12 mycotoxins has been analysed by liquid chromatography - time of flight mass spectrometry in the batch of 60 herbal teas purchased from drugstores in Latvia. Among the dry tea samples, 90% were positive for one to eight mycotoxins. Enniatin B and deoxynivalenol (DON) were the most frequently detected mycotoxins in 55% and 45% of the samples, respectively. DON reached the highest level, from 129 µg kg-1 in herbal blend to 5,463 µg kg-1 in wormwood tea. Ochratoxin A (OTA) and aflatoxin B1 (AFB1) were found in 10% and 20% of the samples at the concentrations ranged between 2.99-30.3 µg kg-1 and 3.40-23.7 µg kg-1. Studies of the tea infusion process indicated that 32-100% of…
Occurrence of Mycotoxins in Botanical Dietary Supplement Infusion Beverages.
2019
The aim of the present work was to study the occurrence of mycotoxins [aflatoxins (1-4), 3-acetyldeoxyniavlenol (5), 15-acetyldeoxynivalenol (6), nivalenol (7), HT-2 (8), T-2 (9), ochratoxin A (10), zearalenone (11), enniatin A (12), enniatin A1 (13), enniatin B (14), enniatin B1 (15), and beauvericin (16)] present in potable products derived from herbal teas. Analysis was carried out by liquid chromatography coupled to ion-trap tandem mass spectrometry (LC-MS/MS-IT) after a dispersive liquid-liquid microextraction procedure (DLLME) was conducted. The DLLME method was applied to 52 commercial samples of chamomile, chamomile with anise, chamomile with honey, linden, pennyroyal mint, thyme, v…