Development of a microchip analytical system with PCR reagents lyophilized into aluminum microchips and modified by the plasma enhanced chemical vapor deposition

Микрочиповые аналитические системы для молекулярно-генетического анализа в последние годы привлекают повышенный интерес исследователей. Алюминиевые микрочипы являются особенно перспективными для внедрения микрочипового формата полимеразной цепной реакции (ПЦР) в лабораторную практику. Подобные микрочипы требуют пассивации поверхности для предотвращения ингибирования ПЦР и улучшения аналитических характеристик системы. Привлекательна и возможность снижения трудозатрат и ошибок оператора за счет лиофилизации реактивов в микрочипах. Микрочипы с лиофилизированными реактивами позволяют избежать сложностей, связанных с хранением при низкой температуре, сокращают количество стадий пипетирования и тем самым уменьшают риск ложноположительных результатов, которые могут быть вызваны контаминацией проб. В работе предложен метод иммобилизации реагентов для ПЦР в микрореакторах алюминиевых микрочипов, поверхность которых была предварительно пассивирована с помощью плазмохимического осаждения из газовой фазы (ПХО). В качестве модельных объектов для лиофилизации выбраны тест-системы для определения фрагмента гена 35S вируса мозаики цветной капусты, используемого в генетически-модифицированных организмах (ГМО), фрагмента геномной ДНК микроорганизма Mycoplasma hominis, а также фрагмента гена глобина человека (белковая часть гемоглобина человека). Разработана экспериментальная установка для лиофилизации, которая позволила оптимизировать условия проведения процесса. Показано, что полученные таким образом алюминиевые микрочипы могут храниться не менее двух месяцев при комнатной температуре, и их аналитические характеристики сравнимы с ПЦР с использованием жидких реактивов, при в 20 раз меньшем потреблении реактивов и в 2-3 раза меньшем количестве операции пипетирования.Microchip analytical systems for the polymerase chain reaction (PCR) have attracted an increased interest of researchers in recent years. Aluminum microchips are particularly promising for the microchip PCR techniques implementation in a routine laboratory practice. However, the surface of the chips needs to be chemically inert for the PCR inhibition prevention and improved analytical characteristics of the system. It should also be noted that the possibility of decreasing of handling procedures and operator mistakes by using lyophilized reagents inside microreactor remains very attractive. Such microchip systems allow avoiding some of the storage difficulties and significantly decrease the number of pipetting stages. All of these lead to minimizing the risk of false positive results due to the sample cross-contamination. In this paper a method of PCR reagents lyophilization into the microreactors of aluminum microchips was developed. The surface of the microchip was modified using the Plasma Enhanced Chemical Vapor Deposition (PE CVD). As the model reagents for the lyophilization, the PCR test systems for 35S gene fragment determination (cauliflower mosaic virus) and human globin (protein part of human GEM) were used. The newly developed experimental system for lyophilization allowed optimizing the process for several microchips. It was shown that the obtained aluminum microchip could be stored under the ambient conditions up to 5 months and their analytical characteristics are comparable with the test-tube PCR, with 20 times less the reagents consumption and 2-3 times less the number of pipetting steps

Analysis of magnesium and levofloxacin complex compounds lipophilicity

The purpose of the study is to evaluate lipophilicity of complex compounds of levofloxacin with magnesium.Цель исследования – оценка липофильности комплексных соединений левофлоксацина с магнием

A compilation of field surveys on gaseous elemental mercury (GEM) from contrasting environmental settings in Europe, South America, South Africa and China: separating fads from facts

Mercury is transported globally in the atmosphere mostly in gaseous elemental form (GEM, Hg0 gas), but still few worldwide studies taking into account different and contrasted environmental settings are available in a single publication. This work presents and discusses data from Argentina, Bolivia, Bosnia and Herzegovina, Brazil, Chile, China, Croatia, Finland, Italy, Russia, South Africa, Spain, Slovenia and Venezuela. We classified the information in four groups: (1) mining districts where this contaminant poses or has posed a risk for human populations and/or ecosystems; (2) cities, where the concentration ofatmospheric mercury could be higher than normal due to the burning of fossil fuels and industrial activities; (3) areas with natural emissions from volcanoes; and (4) pristine areas where no anthropogenic influence was apparent. All the surveys were performed using portable LUMEX RA-915 series atomic absorption spectrometers. The results for cities fall within a low GEM concentration range that rarely exceeds 30 ng m-3, that is, 6.6 times lower than the restrictive ATSDR threshold (200 ng m-3) for chronic exposure to this pollutant. We also observed this behavior in the former mercury mining districts, where few data were above 200 ng m-3.We noted that high concentrations of GEM are localized phenomena that fade away in short distances. However, this does not imply that they do not pose a risk for those working in close proximity to the source. This is the case of the artisanal gold miners that heat the Au–Hg amalgam to vaporize mercury. In this respect, while GEM can be truly regarded as a hazard, because of possible physical–chemical transformations into other species, it is only under these localized conditions, implying exposure to high GEM concentrations, which it becomes a direct risk for humans.Grants CGL2009-13171 and CTM2012-33918 from the Spanish Ministry of Economy and Competitiveness and PII1I09-0142- 4389 from theCastilla-LaMancha (Spain)RegionalGovernment.Published713-7346A. Monitoraggio ambientale, sicurezza e territorioJCR Journalrestricte

Multi-model study of mercury dispersion in the atmosphere : Atmospheric processes and model evaluation

Current understanding of mercury (Hg) behavior in the atmosphere contains significant gaps. Some key characteristics of Hg processes, including anthropogenic and geogenic emissions, atmospheric chemistry, and air-surface exchange, are still poorly known. This study provides a complex analysis of processes governing Hg fate in the atmosphere involving both measured data from ground-based sites and simulation results from chemical transport models. A variety of long-term measurements of gaseous elemental Hg (GEM) and reactive Hg (RM) concentration as well as Hg wet deposition flux have been compiled from different global and regional monitoring networks. Four contemporary global-scale transport models for Hg were used, both in their state-of-the-art configurations and for a number of numerical experiments to evaluate particular processes. Results of the model simulations were evaluated against measurements. As follows from the analysis, the interhemispheric GEM gradient is largely formed by the prevailing spatial distribution of anthropogenic emissions in the Northern Hemisphere. The contributions of natural and secondary emissions enhance the south-to-north gradient, but their effect is less significant. Atmospheric chemistry has a limited effect on the spatial distribution and temporal variation of GEM concentration in surface air. In contrast, RM air concentration and wet deposition are largely defined by oxidation chemistry. The Br oxidation mechanism can reproduce successfully the observed seasonal variation of the RM=GEM ratio in the near-surface layer, but it predicts a wet deposition maximum in spring instead of in summer as observed at monitoring sites in North America and Europe. Model runs with OH chemistry correctly simulate both the periods of maximum and minimum values and the amplitude of observed seasonal variation but shift the maximum RM=GEM ratios from spring to summer. O3 chemistry does not predict significant seasonal variation of Hg oxidation. Hence, the performance of the Hg oxidation mechanisms under study differs in the extent to which they can reproduce the various observed parameters. This variation implies possibility of more complex chemistry and multiple Hg oxidation pathways occurring concurrently in various parts of the atmosphere

A compilation of field surveys on gaseous elemental mercury (GEM) from contrasting environmental settings in Europe, South America, South Africa and China: separating fads from facts

Mercury is transported globally in the atmosphere mostly in gaseous elemental form (GEM, Hg0 gas), but still few worldwide studies taking into account different and contrasted environmental settings are available in a single publication. This work presents and discusses data from Argentina, Bolivia, Bosnia and Herzegovina, Brazil, Chile, China, Croatia, Finland, Italy, Russia, South Africa, Spain, Slovenia and Venezuela. We classified the information in four groups: (1) mining districts where this contaminant poses or has posed a risk for human populations and/or ecosystems; (2) cities, where the concentration ofatmospheric mercury could be higher than normal due to the burning of fossil fuels and industrial activities; (3) areas with natural emissions from volcanoes; and (4) pristine areas where no anthropogenic influence was apparent. All the surveys were performed using portable LUMEX RA-915 series atomic absorption spectrometers. The results for cities fall within a low GEM concentration range that rarely exceeds 30 ng m-3, that is, 6.6 times lower than the restrictive ATSDR threshold (200 ng m-3) for chronic exposure to this pollutant. We also observed this behavior in the former mercury mining districts, where few data were above 200 ng m-3.We noted that high concentrations of GEM are localized phenomena that fade away in short distances. However, this does not imply that they do not pose a risk for those working in close proximity to the source. This is the case of the artisanal gold miners that heat the Au–Hg amalgam to vaporize mercury. In this respect, while GEM can be truly regarded as a hazard, because of possible physical–chemical transformations into other species, it is only under these localized conditions, implying exposure to high GEM concentrations, which it becomes a direct risk for humans

Five-year records of mercury wet deposition flux at GMOS sites in the Northern and Southern hemispheres

International audienceThe atmospheric deposition of mercury (Hg) occurs via several mechanisms, including dry and wet scavenging by precipitation events. In an effort to understand the atmospheric cycling and seasonal depositional characteristics of Hg, wet deposition samples were collected for approximately 5 years at 17 selected GMOS monitoring sites located in the Northern and Southern hemispheres in the framework of the Global Mercury Observation System (GMOS) project. Total mercury (THg) exhibited annual and seasonal patterns in Hg wet deposition samples. Interannual differences in total wet deposition are mostly linked with precipitation volume, with the greatest deposition flux occurring in the wettest years. This data set provides a new insight into baseline concentrations of THg concentrations in precipitation worldwide, particularly in regions such as the Southern Hemisphere and tropical areas where wet deposition as well as atmospheric Hg species were not investigated before, opening the way for future and additional simultaneous measurements across the GMOS network as well as new findings in future modeling studies

Five-year records of mercury wet deposition flux at GMOS sites in the Northern and Southern hemispheres

The atmospheric deposition of mercury (Hg) occurs via several mechanisms, including dry and wet scavenging by precipitation events. In an effort to understand the atmospheric cycling and seasonal depositional characteristics of Hg, wet deposition samples were collected for approximately 5 years at 17 selected GMOS monitoring sites located in the Northern and Southern hemispheres in the frameworkof the Global Mercury Observation System (GMOS) project. Total mercury (THg) exhibited annual and seasonal patterns in Hg wet deposition samples. Interannual differences in total wet deposition are mostly linked with precipitation volume, with the greatest deposition flux occurring in the wettest years. This data set provides a new insight into baseline concentrations of THg concentrations in precipitation worldwide, particularly in regions such as the Southern Hemisphere and tropical areas where wet deposition as well as atmospheric Hg species were not investigated before, opening the way for future and additional simultaneous measurements across the GMOS network as well as new findings in future modeling studies.JRC.D.2-Water and Marine Resource

Atmospheric mercury concentrations observed at ground-based monitoring sites globally distributed in the framework of the GMOS network

International audienc