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1.
Flow injection amperometric detection of ascorbic acid using a Prussian Blue film-modified electrode
The PB film-modified electrode was used as an amperometric detector for flow injection analysis of ascorbic acid. The modified electrode detector showed good sensitivity, stability and reproducibility. The calibration curve for ascorbic acid was linear over the concentration range from 5.0x10(-6) to 1.0x10(-3) mol l(-1) with a slope of 19.9 mA mol(-1) per litre and a correlation coefficient of 0.999. The detection limit of this method was 2.49x10(-6) mol l(-1). The relative standard deviation of six replicate injections of 2.5x10(-4) mol l(-1) ascorbic acid was 2.5%. The results obtained for ascorbic acid determination in pharmaceutical products are in good agreement with those obtained by using the procedure involving the reaction between triiodide and ascorbic acid. 相似文献
2.
The synthesis and properties of a novel class of ortho-dialkylamino-substituted semisquaraines are described. The exceptionally low reactivity of the investigated compounds is caused by an intramolecular hydrogen bond as evidenced by experimental and computational studies. Although this constitutes the reason for our failed attempts to prepare poly(m-phenylene-alt-squaraine)s, the discovered influence of hydrogen bonding on the photophysical properties of these semisquaraines provides a promising new motif for sensor design. 相似文献
3.
Some polishing experiments have been carried out on copper anodes in a hyperbolic cell designed by Gilmont and Walton, using orthophosphoric acid as the electrolyte. The results obtained have been compared to those obtained in similar experiments in a Hull cell. It has been found that very similar bands of different reflectivity and polishes are found to form in both the cells. These bands shift with time and a study of such displacements has been made. The results are briefly discussed. 相似文献
4.
Fernando Oliveira Tartarotti Marcelo Firmino de Oliveira Valdir Roberto Balbo Nelson Ramos Stradiotto 《Mikrochimica acta》2006,155(3-4):397-401
A mercury-free electrode chemically modified with carbon paste containing dimethylglyoxime was used for determination of nickel
in fuel ethanol. The instrumental parameters and composition of the modified paste were optimized. The analytical curve for
nickel determination from 5.0 × 10−9 to 5.0 × 10−7 mol L−1 was obtained using 25 min of accumulation time. The detection limit and amperometric sensitivity obtained for this method
were 2.7 × 10−9 mol L−1 and 5.2 × 108 μA mol−1 L, respectively. The values for nickel concentration in four commercial samples of fuel ethanol were obtained in the range
of 1.1 × 10−8 to 6.9 × 10−8 mol L−1. A comparison to graphite furnace atomic absorption spectrometry (GFAAS) was performed for nickel determination in commercial
samples of ethanol. 相似文献
5.
Tian A. Qiu Valeria Guidolin Khoi Nguyen L. Hoang Thomas Pho Andrea Carra' Peter W. Villalta Jiayi He Xiaoxiao Yao Robert J. Hamers Silvia Balbo Z. Vivian Feng Christy L. Haynes 《Chemical science》2020,11(41):11244
The increasing use of nanoscale lithium nickel manganese cobalt oxide (LixNiyMnzCo1−y−zO2, NMC) as a cathode material in lithium-ion batteries poses risk to the environment. Learning toxicity mechanisms on molecular levels is critical to promote proactive risk assessment of these complex nanomaterials and inform their sustainable development. We focused on DNA damage as a toxicity mechanism and profiled in depth chemical and biological changes linked to DNA damage in two environmentally relevant bacteria upon nano-NMC exposure. DNA damage occurred in both bacteria, characterized by double-strand breakage and increased levels of many putative chemical modifications on bacterial DNA bases related to direct oxidative stress and lipid peroxidation, measured by cutting-edge DNA adductomic techniques. Chemical probes indicated elevated intracellular reactive oxygen species and transition metal ions, in agreement with DNA adductomics and gene expression analysis. By integrating multi-dimensional datasets from chemical and biological measurements, we present rich mechanistic insights on nano-NMC-induced DNA damage in bacteria, providing targets for biomarkers in the risk assessment of reactive materials that may be extrapolated to other nano–bio interactions.The increasing use of nanoscale lithium nickel manganese cobalt oxide (LixNiyMnzCo1−y−zO2, NMC) as a cathode material in lithium-ion batteries poses risk to the environment. We report DNA damage that occurs in bacteria after nano-NMC exposure with rich chemical details. 相似文献
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7.
Carlo Bicchi Cristina Balbo Arianna Binello Angelam D'Amato 《Journal of separation science》1996,19(2):105-110
Two distinct methods are described for determination of residues of ethiofencarb and triforine, and of diflubenzuron, teflubenzuron, and triflumuron at the 0.01 ppm level in apple and pear pulp used for baby food;recoveries are above 50%. Diflubenzuron, teflubenzuron, and triflumuron are extracted with a 1:1 mixture of dichloromethane and acetone, and the extracts are cleaned by SPE using C18 as stationary phase and methanol as mobile phase. Ethiofencarb and triforine are extracted with dichloromethane, and the extracts cleaned using the same stationary phase but a 1:1 mixture of acetonitrile and water as mobile phase. Analysis of both groups of pesticides is by isocratic HPLC—UV at 210 nm using an RP-18 column and acetonitrile-water as mobile phase. 相似文献
8.
In this paper, we report for the first time finite size effects on Néel temperature (T
N) of magnetoelectric BiFeO3 system. Novel wet chemical route has been developed to produce fine particles of BiFeO3 with controlled size and size distribution. Unlike other oxide systems, lattice volume contraction has been observed with
decrease in particle size. The decrease in T
N is co-related to unit cell volume contraction occurring with reduction in particle size. 相似文献
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10.
Cecilia Monticelli Andrea Balbo Carmela Vaccaro Maria Teresa Gulinelli Gian Luca Garagnani 《Applied Physics A: Materials Science & Processing》2013,113(4):1029-1038
In the Civic Museum of Palazzo Schifanoia in Ferrara, a collection of 1104 coin striking tools is stored. Among these, eight steel dies produced from the 2nd decade of the seventeenth to the half of the eighteenth century, representative of the whole period of activity of the papal mint in Ferrara, have been chosen and studied. In that period, while important innovations in the coin minting technique were introduced in Europe, Ferrara declined from the rank of ducal mint to that of peripheral minting center of the highly centralized Papal States. The dies have been characterized by metallographic, chemical, and microhardness investigations. The results suggest that the dies were obtained by a manual smithing technique consisting in hammer hot forging. The die quality improved with time. In fact, in the period 1619–1622, a hardening treatment for the engraved die end consisting in a simple local carburization coexisted with a more efficient production method, based on the application of a proper final heat treatment. This treatment induced a graded microstructure from the engraved end, with a hard martensitic or bainitic structure, to the opposite end, with a tough ferritic/pearlitic structure. From 1675 onward, the latter production method was applied on all the studied dies. The chemical analysis of the alloys suggest that they were likely obtained from iron ores with a common provenance, while the analysis of the slag inclusions suggests the adoption of a direct method of ironmaking throughout the activity period of the mint. 相似文献