Kinetic models of migration of melamine and formaldehyde from melamine kitchenware with data of liquid chromatography

European legislation has established a specific migration limit (SML) of 15 mg kg−1 for formaldehyde and 2.5 mg kg−1 for melamine. Formaldehyde resins are used in the manufacture of melamine kitchenware. Formaldehyde is listed in group 1 of the IARC list of carcinogenic compounds. To determine the quantity of formaldehyde and melamine as potential migrants from different types of melamine kitchenware (glass, mug, cutlery, big cup and bowl), a HPLC-DAD method has been implemented. This method is an alternative to the ones proposed in technical guidelines to determine formaldehyde by UV–vis spectrophotometry and melamine by HPLC. The final objective was to fit the migration kinetic curves of these two analytes in melamine kitchenware. After the method was validated, decision limit (CCα) and detection capability (CCβ) were calculated for both analytes, when the probabilities of false positive (α) and false negative (β) were fixed at 0.05; being CCβ 0.269 mg L−1 and 0.311 mg L−1 for melamine and formaldehyde respectively. CCα and CCβ were also calculated at the SML of both analytes. The migration testing were conducted with simulant B (3% acetic acid (w/v) in aqueous solution), the conditions of each exposure being 70 °C for 2 h. The quantities of melamine and formaldehyde found in the third exposure of the total kitchenware analysed were between 0.21 and 1.09 mg L−1 and between 0.55 and 3.86 mg L−1, respectively. Migration kinetic curves were built for each type of kitchenware with the data of sixteen consecutive migration cycles (70 °C each 30 min). The SML for melamine was surpassed in the mug, in the big cup and in the bowl after eleven, thirteen and one cycles, respectively. When more cycles were carried out in the mug, the values of the accumulated quantity of formaldehyde and melamine were 15.30 and 6.79 mg L−1, respectively, after thirty-two cycles. Both concentrations exceeded the corresponding SML.MINECO (AEI/FEDER, UE) and Consejería de Educación de la Junta de Castilla y León through projects CTQ2017-88894-R and BU012P17 respectively (all co-financed with FEDER funds

Univariate data analysis versus multivariate approach in liquid chromatography. An application for melamine migration from food contact materials

The aim of this work is focused on the melamine migration from food contact materials (FCMs), considering data obtained from univariate analysis versus that obtained from multivariate approach in liquid chromatography coupled to diode array detector. Plastic food contact materials are made from monomers and additives. Moreover, non-intentionally added substances (NIAS) can be part of the composition of the FCM: raw material impurities or process by-products, inks or adhesives. Any compound present within a FCM can migrate to foodstuff. Specific migration of some substances from plastic FCMs to food/simulant is limited by European legislation in force (Commission Regulation No 10/2011). Quantification of analytes in migration samples through a univariate analysis could lead to erroneous results. As an example, in liquid chromatography NIAS can interfere when coeluting with analytes or when they have close retention time. In that case, an overestimation would happen and the verification of the compliance of the specific migration limit (SML) of a substance would be incorrect. A solution to the problem can be found in the application of a chemometric tool with the second-order advantage, which allows the unequivocal identification of analytes. Specifically, for this work, PARAFAC/ PARAFAC2 decomposition technique along with tensors arranged from HPLC-DAD data of migration (test and kinetics) samples were used for the identification and quantification of melamine. Results of melamine quantity found in migration samples from five types of melaware by means of a multivariate approach were compared to results obtained with a univariate data analysis carried out with values of chromatographic peak area as response. The comparison reveals that in test samples, univariate analysis supposes an overestimation in the quantity of melamine of 30 % on average, with respect of the concentration obtained from the multivariate approach. Besides, in kinetics samples it is remarkable that for one migration cycle the melamine found was 10 times above the one that obtained with PARAFAC decomposition. Summing up, multivariate data analysis of migration samples supposes a great advantage in order to comply with the established regulation about migrants and to decrease the false non-compliant results.The authors thank the Consejería de Educación de la Junta de Castilla y León, Spain for financial support through project BU052P20, cofinanced with FEDER funds. M.M. Arce wish to thank JCyL for her postdoctoral contract through project BU052P20

Composition, buoyancy regulation and fate of ice algal aggregates in the central Arctic Ocean

Sea-ice diatoms are known to accumulate in large aggregates in and under sea ice and in melt ponds. There is recent evidence from the Arctic that such aggregates can contribute substantially to particle export when sinking from the ice. The role and regulation of microbial aggregation in the highly seasonal, nutrient- and light-limited Arctic sea-ice ecosystem is not well understood. To elucidate the mechanisms controlling the formation and export of algal aggregates from sea ice, we investigated samples taken in late summer 2011 and 2012, during two cruises to the Eurasian Basin of the Central Arctic Ocean. Spherical aggregates densely packed with pennate diatoms, as well as filamentous aggregates formed by Melosira arctica showed sign of different stages of degradation and physiological stoichiometries, with carbon to chlorophyll a ratios ranging from 110 to 66700, and carbon to nitrogen molar ratios of 8–35 and 9–40, respectively. Sub-ice algal aggregate densities ranged between 1 and 17 aggregates m−2, maintaining an estimated net primary production of 0.4–40 mg C m−2 d−1, and accounted for 3–80% of total phototrophic biomass and up to 94% of local net primary production. A potential factor controlling the buoyancy of the aggregates was light intensity, regulating photosynthetic oxygen production and the amount of gas bubbles trapped within the mucous matrix, even at low ambient nutrient concentrations. Our data-set was used to evaluate the distribution and importance of Arctic algal aggregates as carbon source for pelagic and benthic communities

Contextual determinants of induced abortion: a panel analysis

OBJETIVO Analizar las características contextuales e individuales que explican las diferencias en la tasa de aborto inducido, temporal y territorialmente. MÉTODOS Se realizó un análisis econométrico, con datos panel, de la influencia de la inversión pública en salud y renta per cápita sobre el aborto inducido, además de una medición del efecto de factores sociales y económicos relacionados con el mercado laboral y con la reproducción: empleo femenino, inmigración, fecundidad adolescente y nupcialidad. El ejercicio empírico se realizó con una muestra de 22 países de Europa, para el periodo 2001-2009. RESULTADOS La gran variabilidad territorial del aborto inducido fue consecuencia de factores socioeconómicos contextuales e individuales. Mayores niveles de renta nacional y de inversiones en salud pública, reducen su incidencia. Las siguientes características sociodemográficas también fueron regresores significativos del aborto inducido: empleo femenino, estado civil, migración y fecundidad adolescente. CONCLUSIONES El aborto inducido responde a patrones sociodemográficos, en los que las peculiaridades de cada país son fundamentales. Las desigualdades socioeconómicas, a nivel individual y contextual, afectan de forma significativa su incidencia. Es necesaria más investigación acerca de relaciones entre crecimiento económico, mercado laboral, instituciones y normas sociales, para comprender mejor su variabilidad transnacional, y para poder reducir su incidencia.OBJECTIVE Analyze the contextual and individual characteristics that explain the differences in the induced abortion rate, temporally and territorially. METHODS We conducted an econometric analysis with panel data of the influence of public investment in health and per capita income on induced abortion as well as a measurement of the effect of social and economic factors related to the labor market and reproduction: female employment, immigration, adolescent fertility and marriage rate. The empirical exercise was conducted with a sample of 22 countries in Europe for the 2001-2009 period. RESULTS The great territorial variability of induced abortion was the result of contextual and individual socioeconomic factors. Higher levels of national income and investments in public health reduce its incidence. The following sociodemographic characteristics were also significant regressors of induced abortion: female employment, civil status, migration, and adolescent fertility. CONCLUSIONS Induced abortion responds to sociodemographic patterns, in which the characteristics of each country are essential. The individual and contextual socioeconomic inequalities impact significantly on its incidence. Further research on the relationship between economic growth, labor market, institutions and social norms is required to better understand its transnational variability and to reduce its incidence

Ciclo inmobiliario y demográfico. Un análisis de cointegración para el caso español

The relationship between the real estate cycle and demographic behavior in Spain during the period 1975-2013 is analyzed. The existence of a pattern of behavior between the two cycles following the traditional methodology of time series studies are empirically evaluated. A model error correction is specified. The domain of the long-term effect on the short term is evaluated. The model detects a long-term equilibrium between the two series, a cointegrating equation that displays the domain of the real number estate series.Se analiza la interrelación entre el ciclo inmobiliario y el comportamiento demográfico en España durante 1975 a 2013. Se evalúa empíricamente la existencia de un modelo de comportamiento entre ambos ciclos, siguiendo la metodología tradicional de los estudios de series de tiempo. Se especifica un modelo de corrección de error. Se evalúa el dominio del efecto de largo plazo sobre el corto plazo. El modelo obtenido detecta un equilibrio a largo plazo entre ambas series, ecuación de cointegración que visualiza el dominio de la serie inmobiliaria

Journey to the deep sea: Do Arctic sea-ice bacteria hitchhike on ice-algal aggregates?

In 2012 Arctic sea ice declined to a record minimum. As a consequence of the melting, large sub-ice filaments of the diatom Melosira arctica were released and sank to the seafloor, resulting in a widespread deposition of fresh ice-algal material at 4400 m water depth. Elevated rates of oxygen consumption in sediments with algal deposits indicated remineralization by bacteria and evidenced a response of the entire ecosystem down to the deep sea to elevated carbon flux rates (Boetius et al. 2013, Science 339: 1430-1432). Bacteria play essential roles in carbon and nutrient cycling not only at the seafloor but also in the sea ice and in the water column, contributing significantly to Arctic ecosystem functioning. We sampled a wide range of Arctic environments from the surface to the deep sea, in order to compare bacterial communities from sea ice, melt ponds, surface seawater, deep-sea sediment with and without algal aggregates. Structure and composition of bacterial communities showed strong environmental specificity, with distinct differences between surface and deep-sea environments. Yet, some taxa were shared between algae aggregates from the surface and the seafloor, suggesting a transport of surface-derived bacteria to the deep ocean, as a consequence of rapid sea-ice melt

Procedure to explore a ternary mixture diagram to find the appropriate gradient profile in liquid chromatography with fluorescence detector. Application to determine four primary aromatic amines in napkins

The purpose of this work is to develop a tool to search for a gradient profile with ternary or binary mixtures in liquid chromatography, that can provide well-resolved chromatograms in the shortest time for multianalyte analysis. This approach is based exclusively on experimental data and does not require a retention time model of the compounds to be separated. The methodology has been applied for the quantification of four primary aromatic amines (PAAs) using HPLC with fluorescence detector (FLD). Aniline (ANL), 2,4-diaminotoluene (TDA), 4,4 -methylenedianiline (MDA) and 2-aminobiphenyl (ABP) have been selected since their importance in food contact materials (FCM). In order to achieve that, partial least squares (PLS) models have been fitted to relate CMP (control method parameters) and CQA (critical quality attributes). Specifically, PLS models have been fitted using 30 experiments for each one of the four CQA (resolution between peaks and total elution time), considering 33 predictor variables (the composition of the methanol and acetonitrile in the mobile phase and the time of each one of the 11 isocratic segments of the gradient). These models have been used to predict new candidate gradients, and then, some of those predictions (the ones with resolutions above 1.5, in absolute value, and final time lower than 20 min) have been experimentally validated. Detection capability of the method has been evaluated obtaining 1.8, 189.4, 28.8 and 3.0 μg L−1 for ANL, TDA, MDA and ABP, respectively. Finally, the application of chemometric tools like PARAFAC2 allowed the accurate quantification of ANL, TDA, MDA and ABP in paper napkins in the presence of other interfering substances coextracted in the sample preparation process. ANL has been detected in the three napkins analysed in quantities between 33.5 and 619.3 μg L−1, while TDA is present in only two napkins in quantities between 725.9 and 1908 μg L−1. In every case, the amount of PAAs found, exceeded the migration limits established in European regulations.The authors thank the Consejería de Educación de la Junta de Castilla y León for financial support through project BU052P20, cofinanced with FEDER funds. M.M. Arce wish to thank JCyL for her postdoctoral contract through project BU052P20

Aging and personal finance: a long-term behavior model of the Spanish population

El envejecimiento demográfico determina las características del ámbito económico. La hipótesis de estabilidad en el consumo del ciclo de vida del individuo hace del envejecimiento demográfico un factor que podría afectar al nivel de ahorro agregado. Normalmente, en la modelización del comportamiento de los activos financieros, son los factores de coyuntura económica los tenidos en cuenta quedando el foco demográfico relegado a un segundo plano. Diversos estudios empíricos han encontrado una elevada correlación entre la distribución por edades y las cotizaciones bursátiles. Con base en lo anterior, este trabajo realiza un ejercicio empírico con objeto de captar la conexión entre el papel que las finanzas personales ocupan en el ciclo de vida del individuo y el contexto demográfico. Mediante la especificación de un Modelo de Corrección del Error (MCE) se realiza un análisis de cointegración, que visualiza la vinculación estable a largo plazo entre el consumo de productos financieros y los cambios en la estructura por edades de la población.The aging of a population determines the characteristics of its economic environment and, according to the life-cycle hypothesis, it may affect the level of aggregate saving. Generally, the modeling of financial asset behavior considers factors of economic events and neglects the demographic approach. However, several empirical studies have found a high correlation between age distribution and stock prices. Based on those ideas, this empirical work aims at capturing the connection between the role that personal finance plays in individuals’ lifecycles and their demographic context. By means of an Error Correction Model (ECM), a cointegration analysis was conducted to visualize the stable, long-term relationship between the consumption of financial products and changes in the age structure of the population

Monitoring under ice phyto- and zooplankton blooms with the Nereid Under Ice remotely operated vehicle

The perennially ice-covered Central Arctic is changing rapidly due to extensive sea-ice retreat and the loss of multiyear ice. The thinning of the ice allows more light to reach the water column enhancing productivity. These changes in the under ice ecosystem can lead to under-ice phytoplankton blooms which may increase grazing and carbon export. However, our knowledge of the interactions between sea ice, sub-ice and under-ice communities is still poor, especially in high latitudes. A key limitation is observations of the undisturbed under-ice flora and fauna. To address this gap in observations, the Nereid Under Ice remotely operated vehicle (NUI) was developed, equipped with thin optical fibre and acoustic navigation to explore under-ice environments at distances up to 20 km away from research vessels from which it is deployed. This vehicle can accommodate various interdisciplinary payloads including HD video cameras, CTD and biological sensor packages including chlorophyll fluorometers, CDOM optical sensors and optical nitrate sensors. Research capabilities of NUI were tested during the RV Polarstern PS86 expedition to the Aurora Vent field, at 83ºN 6°W north-east of Greenland. From 12 to 30 July 2014 the evolution of a phytoplankton bloom below 2m thick multiyear ice was followed. Video footage obtained with NUI directly below the ice showed the development of algal mats at the bottom of the ice floe and a succession of zooplankton blooms presumably causing a decline of the phytoplankton bloom. Polar copepods, ctenophores and appendicularia could be identified forming dense biomasses underneath the ice. From NUI’s chlorophyll, CDOM and nitrate profiles, steep gradients of high biogeochemical activity were detected in the mixed layer (upper 6-15 m), which could not be observed by the ship-deployed CTD. These structures were identified as layers of sinking particles with different optical characteristics. This poster summarizes the advantages of robotic observations over classical ship-based sampling for the study of under ice communities. In vivo observations of phyto- and zooplankton communities are needed to better assess the impacts of changing sea-ice conditions on under ice organisms