Longitudinal Changes of Mineral Concentrations in Preterm and Term Human Milk from Lactating Swiss Women.

<b></b> An adequate mineral supply to preterm infants is essential for normal growth and development. This study aimed to compare the mineral contents of human milk (HM) from healthy mothers of preterm (28-32 weeks) and full term (>37 weeks) infants. Samples were collected weekly for eight weeks for the term group (n = 34) and, biweekly up to 16 weeks for the preterm group (n = 27). Iron, zinc, selenium, copper, iodine, calcium, magnesium, phosphorus, potassium, and sodium were quantitatively analyzed by Inductively Coupled Plasma-Mass Spectrometry. The mineral contents of both HM showed parallel compositional changes over the period of lactation, with occasional significant differences when compared at the same postpartum age. However, when the comparisons were performed at an equivalent postmenstrual age, preterm HM contained less zinc and copper from week 39 to 48 (p < 0.002) and less selenium from week 39 to 44 (p < 0.002) than term HM. This translates into ranges of differences (min-max) of 53% to 78%, 30% to 72%, and 11% to 33% lower for zinc, copper, and selenium, respectively. These data provide comprehensive information on the temporal changes of ten minerals in preterm HM and may help to increase the accuracy of the mineral fortification of milk for preterm consumption

Développement d une méthode de fractionnement par couplage flux force (FFF) multi détection pour la caractérisation de colloïdes naturels

Les colloïdes naturels ont une place prépondérante dans les processus environnementaux. Ils peuvent être des vecteurs de polluants et jouent un grand rôle dans les cycles biogéochimiques des éléments. L étude des colloïdes est pendant longtemps restée confidentielle et peu développée du fait d un manque d outils analytiques adaptés. Les travaux menés durant cette thèse concernent le développement de conditions analytiques pour l analyse et le fractionnement par As-Fl-FFF (Asymmetrical Flow- Field Flow Fractionation) de deux grandes familles de colloïdes naturels : les nanoparticules et les acides humiques. Cette technique de fractionnement est associée à plusieurs détecteurs : Ultraviolet/Visible et à diffusion de la lumière (MALLS). Le suivi et la quantification des éléments associés aux colloïdes durant le fractionnement ont également été rendus possibles grâce au couplage avec le spectromètre de masse à couplage inductif (ICP-MS). Enfin, une approche originale combinant fractionnement physique des colloïdes d un lixiviat de décharge et spéciation de l étain associé aux différentes fractions colloïdales a également été réalisée. Cette approche a permis de montrer la potentialité et l importance d une prise en compte de la phase colloïdale lors d analyses environnementales.The role of colloids is crucial in environmental processes. They can control the transport of chemical pollutants and play a major role in biogeochemical cycles. Despite colloids are known for a long time, they remain often neglected in environmental studies due to the lack of convenient analytical tools. This work concerns the development of analytical conditions for the analysis and the fractionation of two main natural colloid populations (nanoparticles and humic acids) by As-Fl-FFF (Asymmetrical Flow-Field Flow Fractionation). This fractionation tool is associated to several detectors as Ultraviolet/Visible and Multi-Angle Laser Light Scattering (MALLS). Monitoring and quantification of trace elements were also performed thanks to the hyphenation with an Inductively Coupled Plasma Mass Spectrometer (ICP-MS). Finally an original approach combining colloidal fractionation of a landfill leachate and chemical speciation of tin associated to its different colloidal fractions was realised. This new approach has shown the potentiality and the importance of colloidal consideration in environmental studies.PAU-BU Sciences (644452103) / SudocSudocFranceF

Kinetic monitoring of trisubstituted organotins in soil after sewage sludge application

cited By 3International audienceOrganotin compounds (OTC) are widely used for their biocidal effects in various agricultural or industrial activities, leading to their environmental presence. Among the organotin species, tributyltin (TBT) and triphenyltin (TPhT) are the most used and are generally considered the most toxic. So it is important to understand their behaviour in soils and obtain data about their persistence and phytoavailability. Many works deal with OTC speciation in various matrices, but few are concerned with OTC degradation in soil. The present study focuses on kinetic monitoring of TBT and TPhT in an agricultural soil. These compounds were introduced into the soil by the way of spiked sewage sludge, simulating agricultural practice and diffuse contamination. The influence of time and initial OTC concentration on the species preservation was evaluated. TBT concentration was shown to have a positive effect on TBT preservation. Corresponding half-lives were calculated. They were 6 ± 1 days and over 39 days for TPhT and TBT, respectively. Degradation compounds, mono- and dibutyltin, and mono- and diphenyltin, were produced by both direct and successive dealkyl and dearylation processes. Copyright © 2008 John Wiley & Sons, Ltd

Assessment of metal–extracellular polymeric substances interactions by asymmetrical flow field-flow fractionation coupled to inductively coupled plasma mass spectrometry

Extracellular polymeric substances (EPSs) excreted by the bacterium Sinorhizobium meliloti and associated Ca, Cd and Pb were characterised by asymmetrical flow field-flow fractionation coupled with UV spectrophotometry and inductively coupled plasma mass spectrometry in terms of molar-mass distributions, number- and weight-average molar masses and polydispersity index. Two major populations with weight-average molar masses of 74 × 10^3 and 1.35 × 10^6 g mol^–1 were obtained for the EPS. Characterisation of the whole EPS–metal interactions evidenced the preferential binding of Ca and Cd to the low molar mass fraction, whereas Pb associated mainly with the high molar mass (HMM) fraction. Comparison with the EPS produced by exoY-mutant, deficient in HMM-EPS excretion, confirmed the preferential binding of Pb to the high molar mass fraction. Enrichment of the EPS with increasing metal concentrations induced the formation of aggregates, which was most pronounced in the presence of 10^–4 mol L^–1 Pb

On-line and off-line quantification of trace elements associated to colloids by As-Fl-FFF and ICP-MS

cited By 27International audienceA quantification procedure of trace elements during colloid size fractionation was developed and validated. This procedure is based on the hyphenation between Asymmetrical Flow Field-Flow Fractionation (As-Fl-FFF) and Inductively Coupled Plasma Mass Spectrometer (ICP-MS). The optimisation of the procedure was performed on a soil leachate spiked with six trace elements selected for their environmental and health impact (As, Cd, Sb, Se, Sn and Pb). The elements in the spiked sample were on-line monitored during the fractionation. The validation was carried out by comparison with a second off-line quantification procedure based on fraction collection and total element analysis by ICP-MS. This off-line one was previously validated using reference materials. Finally, the analytical performances of the two procedures were compared. © 2008 Elsevier B.V. All rights reserved

Characterization of oxidized tannins: comparison of depolymerization methods, asymmetric flow field-flow fractionation and small-angle X-ray scattering Céline Poncet-Legrand

Abstract Condensed tannins are a major class of plant polyphenols. They play an important part in the colour and taste of foods and beverages. Due to their chemical reactivity, tannins are not stable once extracted from plants. A number of chemical reactions can take place, leading to structural changes of the native structures to give so-called derived tannins and pigments. This paper compares results obtained on native and oxidized tannins with different techniques: depolymerization followed by high-performance liquid chromatography analysis, small-angle X-ray scattering (SAXS) and asymmetric flow field-flow fractionation (AF4). Upon oxidation, new macromolecules were formed. Thioglycolysis experiments showed no evidence of molecular weight increase, but thioglycolysis yields drastically decreased. When oxidation was performed at high concentration (e.g., 10 gL −1 ), the weight average degree of polymerization determined from SAXS increased, whereas it remained stable when oxidation was done at low concentration (0.1 gL −1 ), indicating that the reaction was intramolecular, yet the conformations were different. Differences in terms of solubility were observed; ethanol being a better solvent than water. We also separated soluble and non-water-soluble species of a much oxidized fraction. Thioglycolysis showed no big differences between the two fractions, whereas SAXS and AF4 showed that insoluble macromolecules have a weight average molecular weight ten times higher than the soluble ones