Browsing by Author "Jitaru, Petru"
Now showing 1 - 3 of 3
Results Per Page
Sort Options
- Determination of Total Selenium and Selenomethionine in cow milk by HPLC coupled to ICP-MSPublication . Gueifão, Sandra; Coelho, Inês; Castanheira, Isabel; Jitaru, Petru; Fisicaro, PaolaThis study focused on the determination of total selenium and selenomethionine (SeMet) species in milk samples. Accurate determination of total selenium was carried out by Inductively Coupled Plasma Mass Spectrometry and Isotope Dilution (ID-ICP-MS). SeMet species was determined by a hyphenated technique, namely High Performance Liquid Chromatography coupled with ICP-MS equipped with a dynamic reaction cell (HPLC-DRC ICP-MS). In order to eliminate possible interferences (Ar-Ar, Ca-Ca and Ca-Ar) that occur either for determination of total selenium and SeMet, the DRC-ICP-MS operating conditions were optimized, using different flows of gases (Helium/Hydrogen) mixtures. The milk sample was digested by using a closed-vessel microwave system and various parameters, such as the ratio nitric acid/peroxide hydrogen, temperature, pressure and time were investigated. The ID was also compared with the standard addition method. Reproducibility, repeatability and trueness of the method for the determination of total selenium were evaluated using two reference materials, SRM-1549 and BCR-063R. The results obtained were in both cases in a good agreement with certified values. Both enzymatic and acid hydrolysis of the milk proteins were investigated as extraction procedures in view of SeMet determination in milk and the conditions used in this work seemed effective to achieve accurate determination of total selenium and SeMet in this difficult matrix.
- The Impact of Various Types of Cooking on the Fate of Hg and Se in Predatory Fish SpeciesPublication . Ribeiro, Mariana; Douis, Laurène; Silva, José Armando Luísa da; Castanheira, Isabel; Leufroy, Axelle; Jitaru, PetruThis study addresses the effect of various cooking approaches on total Hg (HgT) and total Se (SeT) contents in three predatory fish species. For this purpose, samples of swordfish, dogfish, and tuna from regular French (fish) markets were cooked by boiling, steaming, grilling, and frying, respectively. The levels of HgT and SeT in raw and cooked samples were determined by inductively coupled plasma-mass spectrometry. The data showed a significant increase in HgT and SeT levels between raw and cooked samples (33% of the samples for SeT and 67% for HgT) due to the water loss during the cooking. High intra-species variation related to HgT and SeT levels was found. Considering the level of exposure to HgT through fish consumption and taking also into account the possible protective effect of Se (expressed here via the Se/Hg molar ratio), the safest cooking approach corresponds to grilled swordfish, fried tuna, and steamed dogfish, which show Se/Hg molar ratios of (1.0 ± 0.5), (4.3 ± 4.2), and (1.0 ± 0.6), respectively.
- MERSEL FISH: Development and validation of a new analytical approach for the simultaneous speciation analysis of mercury and selenium by HPLC ICP MSPublication . Mendes Ribeiro, Mariana; Leufroy, Axelle; Danion, Morgane; Castanheira, Isabel; Silva, José Armando; Jitaru, PetruMercury (Hg) is one of the most hazardous chemicals to the environment and the most worrisome contaminant for public health. This is due to its extreme toxicity, particularly in the methylated form which is biomagnified in the food chain, the main pathway of contamination of the humans. The great ability of CH3Hg+ to be bioaccumulated in the aquatic food chain leads to considerably elevated levels of Hg in aquatic organisms, despite nearly immeasurable quantities in the water column. No maximum level for CH3Hg+ is yet regulated by the European commission (EC) in fishery products, despite its extreme toxicity. This is most likely arising from the difficulty in performing accurate speciation analysis of CH3Hg+ in complex matrices such as fishery products. It is also interesting to note that mercury bio-availability seems to be linked to the selenium levels. Although it was shown for a few decades that selenium (Se) shows protective effects against Hg bioaccumulation and toxicity, the mechanism is very poorly understood nowadays. This work report the development and optimization of a new analytical approach for the simultaneous speciation analysis of mercury (Hg2+ and CH3Hg+) and selenium (SeIV, Se VI, SeMet and SeCys) in fish by HPLC-ICP-MS. This method will be employed further for the assessment of dietary exposure to Hg & Se species bio-accumulation by fish, for the analysis of cooked samples as well as for the in vitro simulated digestion studies, to achieve the main aim of this study which is a deep assessment of the Hg-Se interaction in fish and the human dietary exposure.