scholarly journals On the nature of dissolved copper ligands in the early buoyant plume of hydrothermal vents

2018 ◽  
Vol 15 (2) ◽  
pp. 58 ◽  
Author(s):  
Laura Cotte ◽  
Dario Omanović ◽  
Matthieu Waeles ◽  
Agathe Laës ◽  
Cécile Cathalot ◽  
...  
Keyword(s):  
Hydrothermal Vents ◽  
Binding Capacity ◽  
Stripping Voltammetry ◽  
Conditional Stability ◽  
Buoyant Plume ◽  
Conditional Stability Constant ◽  
Sulfur Species ◽  
Inorganic Sulfur ◽  
Competitive Ligand Exchange ◽  
High Concentrations

Environmental contextCopper released by deep-sea hydrothermal vents has been recognised to be partly stabilised against precipitation by its complexation with strong Cu binding ligands. Yet, the sources and nature of these compounds in such environments are still not fully understood. This study shows that the Cu ligands detected are hydrothermally sourced and could be mainly inorganic sulfur species. AbstractThe apparent speciation of Cu in the early buoyant plume of two black smokers (Aisics and Y3) from the hydrothermal vent field Lucky Strike (Mid-Atlantic Ridge) was investigated using competitive ligand exchange-adsorptive cathodic stripping voltammetry (CLE–AdCSV). We have assessed the apparent Cu-binding ligand concentration ([L]) and the corresponding conditional stability constant (log K′) for 24 samples. At the smoker Aisics, [L] ranged from 18.2 to 2970 nM. Log K′CuL ranged from 12.4 to 13.4. At Y3, the binding capacity of natural ligands was from 32.5 to 1020 nM, with Log K′CuL ranging from 12.5 to 13.1. Total dissolved Cu ranged from 7.0 to 770 nM and from 12.7 to 409 nM at Aisics and Y3, respectively. Our results show that the amount of ligand L increases with dissolved Mn (dMn) concentrations, suggesting a hydrothermal origin of the Cu-binding ligands detected. In addition, such high concentrations of Cu-binding ligands can only be explained by an additional abiotic source differing from organic processes. Based on the massive in situ concentrations of free sulfides (up to 300 µM) and on the striking similarities between our log K′CuL and the log K′Cu(HS) previously published, we infer that the Cu-binding ligands could be predominantly inorganic sulfur species in the early buoyant plume of the two vent sites studied.

Method for the differentiation of leaf litter extracts and study of their interaction with Cu(II) by molecular fluorescence

1998 ◽  
Vol 76 (8) ◽  
pp. 1197-1209 ◽  
Author(s):  
Joaquim CG Esteves da Silva ◽  
Adélio ASC Machado ◽  
Miguel A Ferreira ◽  
Francisco Rey
Keyword(s):  
Leaf Litter ◽  
Binding Sites ◽  
Extraction Procedure ◽  
Castanea Sativa ◽  
Fulvic Acids ◽  
Conditional Stability ◽  
Conditional Stability Constant ◽  
Two Samples ◽  
Molecular Fluorescence ◽  
High Concentrations

Six leaf litter extracts (LLE) (eucalyptus (Eucaliptus globulus), fern (Pteridium aquilinium), oak (Quercus robur), chestnut (Castanea sátiva), laurel (Laurus nobilis), and ulex (Ulex europoeus) canopies) were isolated following an extraction procedure similar to that used for fulvic acids (FA) and were characterized by elemental analysis and UV-Vis, FT-IR, and synchronous molecular fluorescence (SyF) spectroscopies. Moreover, information about their interaction with the Cu(II) ion in aqueous solution (100 mg yL of LLE in 0.1 M KNO3 at pH = 6) was obtained from the measurement of SyF spectra at increasing concentrations of Cu(II). These spectral sets were treated by a self-modeling mixture analysis method (SIMPLISMA) to obtain improved quenching profiles to be used in the estimation by the method of Ryan and Weber of the conditional stability constants (Kc), concentration of binding sites, and percentage of fluorescent binding sites accessible for complexation. For comparison purposes, two samples of FA extracted from two horizons of an oak forest soil (0-5 cm and 5-15 cm) were also studied. The spectroscopic data obtained for LLE and FA were different. The results suggest that LLE are characterized by relatively high concentrations of individualized simple molecules and include reactive structures (alkene and protein residues). The ratio of aliphatic yaromatic structures was higher in LLE than for FA. Both LLE and soil FA form stable complexes with Cu(II), but the logarithm of the conditional stability constant of the 1:1 complexes is larger for LLE (about 5) than for the soil FA (about 4.5).Key words: leaf litter extracts, soil fulvic acids, synchronous fluorescence, Cu(II) complexation, SIMPLISMA, spectral pattern recognition.

Heavy metal (Zn and Cu) complexation and molecular size distribution in wastewater treatment plant effluent

2008 ◽  
Vol 58 (6) ◽  
pp. 1207-1213 ◽  
Author(s):  
G. G. T. Chaminda ◽  
F. Nakajima ◽  
H. Furumai
Keyword(s):  
Wastewater Treatment ◽  
Wastewater Treatment Plant ◽  
Anodic Stripping Voltammetry ◽  
Treatment Plant ◽  
Molecular Size ◽  
Stripping Voltammetry ◽  
Conditional Stability ◽  
Conditional Stability Constant ◽  
Conditional Stability Constants ◽  
Molecular Size Distribution

The size distributions of zinc and copper species in the effluent of a wastewater treatment plant were determined by a combination of ultrafiltration and chelating disk cartridge fractionation. The results showed that 75–87% of total Zn and 84–86% of total Cu were strongly complexed or particle-bound in the final effluents. It was also found that the major part of Cu was bound to ligands in the <500 Da fraction while the trend for Zn was not so clear and exhibited significant seasonal variability. Labile Cu and Zn were detected not only in the smallest fraction (<500 Da) but also in the larger fractions. It meant that the labile species in the effluent were not equivalent to free metal ions. Conditional stability constants and ligand concentrations were also determined from the measured metal concentrations by square wave anodic stripping voltammetry. Existence of two types of ligand for each metal was inferred from the experimental data. Conditional stability constant obtained for the stronger type Ligand of Zn was higher than that of Cu, although the estimated Ligand concentrations were almost similar.

scholarly journals Electroanalytical Techniques for the Detection of Selenium as a Biologically and Environmentally Significant Analyte—A Short Review

Molecules ◽  
2021 ◽  
Vol 26 (6) ◽  
pp. 1768
Author(s):  
Miroslav Rievaj ◽  
Eva Culková ◽  
Damiána Šandorová ◽  
Zuzana Lukáčová-Chomisteková ◽  
Renata Bellová ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Essential Element ◽  
Analytical Techniques ◽  
High Sensitivity ◽  
Stripping Voltammetry ◽  
Short Review ◽  
Electroanalytical Methods ◽  
High Concentrations ◽  
Speed Of Analysis

This short review deals with the properties and significance of the determination of selenium, which is in trace amounts an essential element for animals and humans, but toxic at high concentrations. It may cause oxidative stress in cells, which leads to the chronic disease called selenosis. Several analytical techniques have been developed for its detection, but electroanalytical methods are advantageous due to simple sample preparation, speed of analysis and high sensitivity of measurements, especially in the case of stripping voltammetry very low detection limits even in picomoles per liter can be reached. A variety of working electrodes based on mercury, carbon, silver, platinum and gold materials were applied to the analysis of selenium in various samples. Only selenium in oxidation state + IV is electroactive therefore the most of voltammetric determinations are devoted to it. However, it is possible to detect also other forms of selenium by indirect electrochemistry approach.

scholarly journals Spectrophotometric determination of dothiepin hydrochloride in pharmaceuticals through ion-pair complexation reaction

2012 ◽  
Vol 18 (2) ◽  
pp. 339-347 ◽  
Author(s):  
Sameer Abdulrahman ◽  
Kanakapura Basavaiah
Keyword(s):  
Ion Pair ◽  
Pure Form ◽  
Bromocresol Green ◽  
Bromophenol Blue ◽  
Complexation Reaction ◽  
Conditional Stability ◽  
Conditional Stability Constant ◽  
Accuracy And Precision ◽  
Significant Difference

Two simple, sensitive and extraction-free spectrophotometric methods are described for the determination of dothiepin hydrochloride (DOTH) both in pure form and in pharmaceutical tablets. The methods are based on ion-pair complex formation between dothiepin base (DOT) and two acidic dyes, namely, bromophenol blue (BPB) or bromocresol green (BCG) with absorption maximum at 425 nm for BPB method or 430 nm for BCG method. Beer?s law is obeyed over the concentration ranges of 1.0-15.0 and 1.0-17.5 ?g mL-1 DOT for BPB and BCG methods, respectively. The molar absorptivity values and Sandell?s sensitivity values are reported for both methods. The limits of detection (LOD) and quantification (LOQ) were calculated to be 0.18 and 0.53 ?g mL-1 for BPB method, and 0.17 and 0.50 ?g mL-1 for BCG method, respectively. The stoichiometry of the complex in either case was found to be 1: 1 and the conditional stability constant (KF) of the complexes has also been calculated. The proposed methods were applied successfully to the determination of DOTH in pure form and in its tablet form with good accuracy and precision. Statistical comparison of the results was performed using Student's t-test and variance ratio F-test at 95% confidence level and there was no significant difference between the official and proposed methods with regard to accuracy and precision. Further, the validity of the proposed methods was confirmed by recovery studies via standard addition technique.

Measuring Marine Iron(III) Complexes by CLE-AdSV

2005 ◽  
Vol 2 (2) ◽  
pp. 80 ◽  
Author(s):  
Raewyn M. Town ◽  
Herman P. van Leeuwen
Keyword(s):  
Ligand Exchange ◽  
Essential Element ◽  
Stripping Voltammetry ◽  
Chemical Form ◽  
Kinetic Properties ◽  
Marine Systems ◽  
Dissolved Ions ◽  
Competitive Ligand Exchange ◽  
Concentration Limits ◽  
Kinetic Features

Environmental Context. Iron is an essential element for life in the world's oceans, and in some regions its concentration limits the growth of phytoplankton. The amount of iron(iii) which is available to an organism depends on the exact chemical form in which it exists, for example as dissolved ions or associated with organic compounds. There are widespread reports that marine iron(iii) is predominantly bound in extremely strong complexes. We show that such claims might be the result of an artefact of the measurement technique, CLE-AdSV. Ensuing ideas about the iron biogeochemistry in marine systems might require reconsideration as well. Abstract. Iron(iii) speciation data, as determined by competitive ligand exchange?adsorptive stripping voltammetry (CLE-AdSV), is reconsidered in the light of the kinetic features of the measurement. The very large stability constants reported for iron(iii) in marine ecosystems are shown to be possibly due to an artefact of the technique, arising from the assumption that equilibrium is achieved between all iron(iii) species of relevance. Particular kinetic properties, related to the special nature of hydroxide as a metal complexant, have the consequence that CLE-AdSV measurements of iron(iii) in seawater generally correspond to the hydroxide complexes only. By the same token, dissolved hydroxide complexes are the key components of the bioavailable iron(iii) pool. The analysis presented herein opens opportunities to exploit CLE-AdSV for more rigorous investigation of the links between the speciation and the bioavailability of iron(iii).

scholarly journals Vitamin B12 transport in blood. I. Congenital deficiency of transcobalamin II

Blood ◽  
1975 ◽  
Vol 45 (1) ◽  
pp. 71-82 ◽  
Author(s):  
E Gimpert ◽  
M Jakob ◽  
WH Hitzig
Keyword(s):  
Vitamin B12 ◽  
Binding Capacity ◽  
Polyacrylamide Gel Electrophoresis ◽  
Congenital Deficiency ◽  
Complete Clinical Remission ◽  
High Concentrations ◽  
High Doses ◽  
Vitamin B12 Binder ◽  
Very High ◽  
Transcobalamin Ii

Abstract Some characteristics of vitamin B12 binding and transport in the serum of an infant with congenital hereditary transcobalamin II (TC II) deficiency were studied using the following parameters and methods: vitamin B12 level and binding capacity; electrophoretic mobility in polyacrylamide gel electrophoresis; various immunodiffusion and absorption experiments, using a specific anti-TC II antiserum and the patient's serum as antigen. The results of these studies point to a deficient synthesis of TC II. Parenteral administration of high doses of vitamin B12 was followed by rapid and complete clinical remission and the appearance of vitamin B12 binder in the alpha 2 region which is similar to “fetal binder.” Thus, very high concentrations of vitamin B12, either carrier free or bound to this alpha 2 binder, were able to correct the disturbed physiology of TC II deficiency, presumably by normalization of DNA-thymine synthesis.

Effect of UVB Irradiation on Cu2+-Binding Organic Ligands and Cu2+ Speciation in Alpine Lake Waters of New Zealand

2005 ◽  
Vol 2 (1) ◽  
pp. 56 ◽  
Author(s):  
Sylvia Sander ◽  
Jonathan P. Kim ◽  
Barry Anderson ◽  
Keith A. Hunter
Keyword(s):  
New Zealand ◽  
Surface Waters ◽  
Natural Waters ◽  
Austral Summer ◽  
Organic Ligands ◽  
Conditional Stability ◽  
Uvb Radiation ◽  
Dissolved Metals ◽  
Conditional Stability Constant ◽  
Uvb Irradiation

Environmental Context. The bioavailability of dissolved metals in natural waters is directly affected by metal-sequestering agents. These agents include soil-derived matter and compounds released by microorganisms, since copper can support or inhibit aquatic microorganisms depending on concentration. During summer the levels of copper increase in surface waters, an effect intuitively attributable to increased ultraviolet light degrading the sequestering agents more effectively, leading to a concurrent release of the metal. This paper shows that the amount of degradation attributable to light is too low to explain the metal release and that a biological influence may instead be responsible. Abstract. The influence of UVB irradiation on the Cu2+ binding by natural organic ligands in six alpine lakes on the South Island, New Zealand, has been investigated using competitive ligand equilibration with salicylaldoxime and detection by cathodic stripping voltammetry (CLE-CSV). During austral summer 2002–2003 the total dissolved Cu ([Cu]T), the concentration of strong Cu2+-binding ligands ([L]T), and their conditional stability constant K´´ were determined in surface samples of all six lakes. All lakes exhibited appreciable concentrations of a strong Cu2+ binding ligand with similar K´´ values and concentrations always exceeding [CuT], thus dominating Cu2+ speciation. Four lakes (Hayes, Manapouri, Wanaka, Te Anau) showed no appreciable trend in [LT] throughout the summer, whereas in Lakes Wakatipu and Hawea [LT] increased steadily throughout this period. Laboratory UVB irradiation of lake water samples using a 400 W mercury lamp with a Pyrex glass filter (λ > 280 nm) showed that Cu2+-binding ligands are destroyed by UVB radiation, causing [L]T to decrease with a rate of –0.588 nmol L–1 h–1 (r2 0.88). From this we calculate that the in situ ligand destruction rate by UVB in summer for surface waters of these lakes is too small to significantly affect [LT], and conclude that variations in ligand concentrations must result from seasonally variable biological factors.

scholarly journals Spectrophotometric determination of nicradipine and isradipine in pharmaceutical formulations

2009 ◽  
Vol 15 (2) ◽  
pp. 69-76 ◽  
Author(s):  
S.M. Al-Ghannam ◽  
A.M. Al-Olyan
Keyword(s):  
Standard Deviation ◽  
Detection Limit ◽  
Reaction Pathway ◽  
Pharmaceutical Preparations ◽  
Pharmaceutical Formulations ◽  
Molar Absorptivity ◽  
Zinc Powder ◽  
Conditional Stability ◽  
Conditional Stability Constant

A sensitive spectrophotometric method was developed for the determination of some 1,4-dihydropyridine compounds namely, nicardipine and isradipine either in pure form or in pharmaceutical preparations. The method is based on the reduction of nicardipine and isradipine with zinc powder and calcium chloride followed by further reduction with sodium pentacyanoaminoferrate (II) to give violet and red products having the absorbance maximum at 546 and 539 nm with nicardipine and isradipine, respectively. Beer's law was obeyed over the concentration range 8.0-180 ?g/ml with the detection limit of 1.67 ?g/ml for nicardipine and 8.0-110 ?g/ml with the detection limit of 1.748 ?g/ml for isradipine. The analytical parameters and their effects on the reported methods were investigated. The molar absorptivity, quantization limit, standard deviation of intercept (Sa), standard deviation of slope (Sb) and standard deviation of the residuals (Sy/x) were calculated. The composition of the result compounds were found 1:1 for nicardipine and 1:2 for isradipine by Job's method and the conditional stability constant (Kf) and the free energy changes (?G) were calculated for compounds formed. The proposed method was applied successfully for the determination of nicardipine and isradipine in their dosage forms. The results obtained were in good agreement with those obtained using the reference or official methods. A proposal of the reaction pathway was presented.

scholarly journals The natural barrier to retention of the high concentration of gases: methane and carbon dioxide, methane and hydrogen under hydrothermal vents

2019 ◽  
pp. 11
Author(s):  
T.A. Smaglichenko
Keyword(s):  
Hydrothermal Vents ◽  
Geochemical Data ◽  
3D Seismic ◽  
Seismic Model ◽  
High Concentration ◽  
Geological Structures ◽  
Diffusion Parameters ◽  
High Concentrations ◽  
Tomography Method ◽  
Natural Barrier

The assumed seismic model of the area around fields having high concentrations of CH4 and CO2, CH4 and H2 dissolved in hydrothermal vents is first introduced. The model of so-called natural barrier to retention of gases accumulation has been revealed using outcomes of 3D seismic tomography method, which has been developed by the author and utilizing geochemical data that were earlier obtained by other researchers in scientific cruises and university laboratories. The built model is in agreement with a distribution of seismicity (M 2.5–4.5) that occurred during last 5 years. A comparison of diffusion parameters of methane for thermal reservoirs and rocks, and corresponding comparison of geological structures permits to suppose that the presented model can be used to find appropriated area for underground storage of gases mentioned above.

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