The voltammetric determination of cobalt(II) in seawater – adsorptive preconcentration of the dimethylglyoxime complex

1990 ◽  
Vol 68 (2) ◽  
pp. 209-213 ◽  
Author(s):  
W. W. Westenbrink ◽  
J. A. Page ◽  
G. W. VanLoon
Keyword(s):  
Reference Sample ◽  
Stripping Voltammetry ◽  
Reduction Peak ◽  
Analytical Sensitivity ◽  
Adsorbed Complex ◽  
Seawater Samples ◽  
The One ◽  
Reduction Peak Potential ◽  
Good Agreement

Conditions for the determination of trace Co in seawater are described. The method involves formation of the dimethylglyoxime complex and adsorptive accumulation onto a hanging mercury drop electrode at an applied potential of −0.70 or −0.96 V vs. SCE. The adsorbed complex is then reduced by scanning the electrode potential to −1.20 V; the reduction peak potential (Ep) is −1.12 V. Nickel behaves in a similar manner with Ep of −0.99 V but the Co complex appears to be preferentially adsorbed, making analysis for Co possible even in the presence of a large excess of Ni. Adsorption of organic matter also occurs; this does not affect analytical sensitivity but limits the maximum deposition time allowed in the analysis.Determination of Co in six seawater samples yielded results ranging from 4 to 114 ng L−1. Good agreement was obtained with the one reference sample (NASS-1) for which there was a certificate value. Keywords: cobalt, dimethylglyoxime, stripping voltammetry, adsorption, seawater.

Determination of trace amounts of lead by adsorptive cathodic stripping voltammetry with L-3-(3,4-Dihydroxyphenyl)alanine

2009 ◽  
Vol 74 (4) ◽  
pp. 599-610 ◽  
Author(s):  
Mohammad Bagher Gholivand ◽  
Alireza Pourhossein ◽  
Mohsen Shahlaei
Keyword(s):  
Lead Concentration ◽  
Stripping Voltammetry ◽  
Optimum Conditions ◽  
Lead In Blood ◽  
Accumulation Time ◽  
Cathodic Stripping Voltammetry ◽  
Voltammetric Measurement ◽  
Adsorbed Complex ◽  
Reduction Current

A sensitive and selective procedure is presented for the voltammetric determination of lead. The procedure involves an adsorptive accumulation of lead L-3-(3,4-dihydroxyphenyl)alanine (LDOPA) on a hanging mercury drop electrode, followed by a stripping voltammetric measurement of reduction current of an adsorbed complex at –0.15 V (vs Ag|AgCl). Optimum conditions for lead analysis include pH 8.5, 80 μM LDOPA and accumulation potential –0.15 V (vs Ag|AgCl). The peak currents are proportional to the lead concentration 1–300 nmol l–1 with a detection limit of 0.6 nmol l–1 and accumulation time 60 s. The method was used for the determination of lead in blood, dry tea and also in waters.

scholarly journals Nanostructured materials for sensing Pb(II) and Cd(II) ions: Manganese oxohydroxide versus carbonized polyanilines?

2013 ◽  
Vol 78 (11) ◽  
pp. 1717-1727 ◽  
Author(s):  
Biljana Sljukic ◽  
Darko Micic ◽  
Nikola Cvjeticanin ◽  
Gordana Ciric-Marjanovic
Keyword(s):  
Nanostructured Materials ◽  
Electrode Materials ◽  
Anodic Stripping Voltammetry ◽  
Aqueous Media ◽  
Stripping Voltammetry ◽  
Lead And Cadmium ◽  
Manganese Oxyhydroxide ◽  
The One ◽  
Lower Limits

Nanostructured materials including three different carbonized polyanilines and manganese oxyhydroxide were prepared and evaluated as electrode materials for sensing of lead and cadmium ions in aqueous media. Anodic stripping voltammetry results indicated that all prepared materials could be successfully used for determination of these two heavy metal ions. Carbonized polyaniline-based electrodes have higher signal and lower limits of detection (10-7 ?) compared to manganese oxyhydroxide-based electrode. Among the three studied carbonized polyanilines, the one that was derived from polyaniline precursor produced in the presence of 3,5-dinitrosalicyclic acid showed the highest electrocatalytic activity towards the lead and cadmium oxidation.

scholarly journals Inhibitive Determination of Hg(II) in Aqueous Solution Using Urease Amperometric Biosensor

2019 ◽  
Vol 19 (3) ◽  
pp. 786 ◽  
Author(s):  
Dhony Hermanto ◽  
Bambang Kuswandi ◽  
Dwi Siswanta ◽  
Mudasir Mudasir
Keyword(s):  
Dynamic Range ◽  
Limit Of Detection ◽  
Absorption Spectrometry ◽  
Amperometric Biosensor ◽  
Reduction Peak ◽  
Polyelectrolyte Complexes ◽  
Indirect Determination ◽  
Biosensor Response ◽  
Good Agreement

An amperometric biosensor for the indirect determination of Hg(II) has been developed based on inhibition of urease (EC 3.5.1.5) immobilized into alginate–chitosan polyelectrolyte complexes membrane. The biosensor response was monitored by following the reduction peak of hydrolyzed urea at around -0.15 V. The amperometric biosensor has a dynamic range 40–90 ppb Hg(II) with limit of detection of 66.45 ppb toward Hg(II) ions, repeatability (CV) value of 0.86% and only Ag(I) as the main potential interference. The sensor shows a stable and reproducible response for more than 2 weeks when it stored dry at 4 °C. The analytical results of Hg(II)-spiked water sample showed a good agreement with those obtained by atomic absorption spectrometry method, suggesting that the developed method may be applied in the determination of Hg(II) in the water samples.

scholarly journals Interaction study of moxifloxacin with Cu(II) ion using square-wave voltammetry and its application in the determination in tablets

2006 ◽  
Vol 31 (1) ◽  
pp. 31-38 ◽  
Author(s):  
M. A. G. Trindade ◽  
P. A. C. Cunha ◽  
T. A. de Araújo ◽  
G. M. da Silva ◽  
V. S. Ferreira
Keyword(s):  
Square Wave Voltammetry ◽  
Reduction Peak ◽  
Interaction Study ◽  
Accumulation Time ◽  
Square Wave ◽  
Wave Voltammetry ◽  
Electroanalytical Method ◽  
Limit Detection ◽  
Good Agreement

This work presents an electroanalytical method for the determination of moxifloxacin (MOXI) in tablets by its interaction with Cu(II) ion and subsequent electrochemical reduction at hanging mercury drop electrode (HMDE). A well-defined reduction peak at -0.21 V vs. Ag/AgCl in Phosphate buffer 0.04 mol L-1 pH 8.0 was observed for the complex reduction MOXI-Cu(II), using square-wave voltammetry (SWV). Using a 10 s of accumulation time at -0.40 V was found a limit detection of 3.60x10-8 mol l-1. The obtained results have shown good agreement with those obtained by spectrophotometric method.

Monoclonal antibody-based immunoenzymometric assays of retinol-binding protein

1993 ◽  
Vol 39 (3) ◽  
pp. 472-476 ◽  
Author(s):  
A B Pereira ◽  
S K Nishida ◽  
J G Vieira ◽  
M T Lombardi ◽  
M S Silva ◽  
...  
Keyword(s):  
Binding Protein ◽  
Retinol Binding Protein ◽  
Good Precision ◽  
Routine Work ◽  
One Step ◽  
High Concentrations ◽  
The One ◽  
Convoluted Tubules ◽  
Good Agreement

Abstract Retinol-binding protein (RBP) is a low-molecular-mass protein (21 kDa), easily filtered in renal glomeruli and very efficiently reabsorbed by the proximal convoluted tubules (PCTs). In PCT dysfunction, high concentrations of RBP are found in urine. Several methods have been used to determine RBP in serum or urine. We describe the production, selection, labeling, and utilization of anti-RBP monoclonal antibodies in two- or one-step immunoenzymometric assays for the determination of RBP. The one-step assay has good precision, with within-run and between-run CVs < 6.6% and 5.9%, respectively. Comparison with radial immunodiffusion (x) showed good agreement: y = 0.068 mg/L + 0.899x (n = 24). Comparison between the one-step (y) and two-step (x) versions of the assay also showed a very good correlation: y = 212 micrograms/L + 0.910x. The one-step assay has been adopted for routine work; it detects transthyretin-bound as well as free RBP and may have clinical usefulness in evaluating the functional status of PCTs.

scholarly journals Determination of Plasma Electron Temperature from the Reversal of Radial Ambipolar Electric Field in a Longitudinal Magnetic Field

1972 ◽  
Vol 27 (10) ◽  
pp. 1439-1443 ◽  
Author(s):  
Günter Franck ◽  
R. Held ◽  
H. D. Pfeil
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Longitudinal Magnetic Field ◽  
Plasma Electron ◽  
Langmuir Probes ◽  
Field Reversal ◽  
Field Diffusion ◽  
The One ◽  
Good Agreement

Abstract When a longitudinal magnetic field is superimposed to a low pressure plasma, reversal of the radial ambipolar electric field takes place at a definite magnetic field Br. From the Br-values electron temperatures Te in the plasma can be found, when classical magnetic field diffusion exists. In the negative H2-and He-glow plasmas with superimposed longitudinal magnetic field, electron temperatures have been measured on the one hand by the method of electric field reversal and on the other hand with Langmuir probes. There is a fairly good agreement between the Te-values obtained by both methods.

scholarly journals Polarographic determination of DNA based on its interaction with the phenanthroline-zinc(II) complex

2015 ◽  
Vol 80 (1) ◽  
pp. 87-96
Author(s):  
Ni Hui ◽  
Aiqin Liang ◽  
Changhui Xue ◽  
Wei Sun
Keyword(s):  
Reduction Peak ◽  
Determination Limit ◽  
Peak Potential ◽  
Buffer Solution ◽  
Peak Current ◽  
Reduction Peak Current ◽  
Relative Standard ◽  
Reduction Peak Potential ◽  
Voltammetric Technique

By using the linear sweep voltammetric technique, a phenanthroline (Phen) and zinc(II) (Phen-Zn(II)) complex was used as the electrochemical probe for the determination of double-stranded (ds) DNA. In pH 9.0 Britton- -Robinson (B-R) buffer solution, Phen can interact with Zn(II) to form a stable electroactive [Phen-Zn(II)] complex, which had a sensitive second order derivative polarographic reductive peak at -1.300 V (vs. SCE). After the addition of dsDNA into a solution of Phen-Zn(II) complex, the reduction peak current decreased with a negative shift of the reduction peak potential and without the appearance of new peaks. The results showed that a new supramolecular complex was formed via interaction of the Phen-Zn(II) complex with dsDNA. The conditions of interaction and the electrochemical detection were carefully investigated. Under the optimum conditions, the decrease in the reduction peak current was directly proportional to the dsDNA concentration in the range of 0.4-18.0 mg L-1 with the linear regression equation: ?Ip?/nA = 349.48 + + 84.647(c/mg L-1) (n = 13, ? = 0.991) and a determination limit of 0.20 mg L-1 (3?). The relative standard deviation (RSD) for 10 parallel determinations of 10.0 mg L-1 dsDNA was found to be 2.03 %. The method was successfully applied to the detection of synthetic samples with satisfactory results.

scholarly journals Trace and selective determination of cobalt(II) in water and salt samples using cathodic adsorptive stripping voltammetry in the presence of pyrogallol red

2013 ◽  
Vol 78 (5) ◽  
pp. 717-724 ◽  
Author(s):  
Foroozan Hasanpour ◽  
Hossein Teimori ◽  
Masoud Fouladgar ◽  
Masoumeh Taei
Keyword(s):  
Stripping Voltammetry ◽  
Optimum Conditions ◽  
Accumulation Time ◽  
Selective Determination ◽  
Cathodic Stripping Voltammetry ◽  
Pyrogallol Red ◽  
Adsorbed Complex ◽  
Scan Rate ◽  
Reduction Current

A sensitive and selective procedure is presented for voltammetric determination of cobalt. The procedure involves an adsorptive accumulation of cobalt pyrogallol red (PGR) complex on stationary mercury drop electrode, followed by cathodic stripping voltammetry measurement of reduction current of adsorbed complex at -1.17 V (vs. Ag/AgCl). The optimum conditions for determination of cobalt include pH 11.0, 35 ?M pyrogallol red, an accumulation potential of -0.9 V (vs. Ag/AgCl) and scan rate 80 mVs-1. The peak current is proportional to the concentration of cobalt over the concentration range of 5.0 to 280 ng mL-1 with a detection limit of 1 ng mL-1 with an accumulation time of 140 s. The method was applied for the determination of cobalt in analytical grade NaCl and water samples.

Clinical Application of a Chromogenic Substrate Method for Determination of Factor VIII Activity

1985 ◽  
Vol 54 (04) ◽  
pp. 818-823 ◽  
Author(s):  
S Rosén ◽  
M Andersson ◽  
M Blombäck ◽  
U Hégglund ◽  
M J Larrieu ◽  
...  
Keyword(s):  
Factor Viii ◽  
Clinical Application ◽  
Healthy Subjects ◽  
Hemophilia A ◽  
Chromogenic Substrate ◽  
Factor Viii Activity ◽  
One Stage ◽  
The One ◽  
Good Agreement

SummaryA chromogenic substrate kit for the determination of factor VIII activity (COATEST® Factor VIII) has been evaluated in five different laboratories, one of them using a semi-automated procedure. This chromogenic method was compared to one-stage clotting assays for factor VIII determination in plasmas from healthy subjects, carriers of hemophilia A, severe, mild and moderate hemophilia A as well as von Willebrand’s patients. In all these cases, a high correlation between these two methods was obtained (r = 0.96-0.99, n = 385) with a good agreement of the assigned potencies at all levels of factor VIII. A good correlation (r = 0.94) was also obtained for the levels of factor VIII after infusion of concentrates in six severe hemophiliacs or after administration of DDAVP to von Willebrand’s patients.The chromogenic method is insensitive to preactivation of factor VIII by thrombin, thus yielding valid potency assignments also in these situations.The precision was higher with the chromogenic method than with the one-stage clotting assays (C.V. = 2-5% vs 4-15%). Altogether, the new chromogenic substrate method has proven itself suitable for determination of factor VIII in plasma and concentrates.

scholarly journals Iron Speciation in Fram Strait and Over the Northeast Greenland Shelf: An Inter-Comparison Study of Voltammetric Methods

2021 ◽  
Vol 7 ◽  
Author(s):  
Indah Ardiningsih ◽  
Kechen Zhu ◽  
Pablo Lodeiro ◽  
Martha Gledhill ◽  
Gert-Jan Reichart ◽  
...  
Keyword(s):  
Stripping Voltammetry ◽  
Data Interpretation ◽  
Organic Ligands ◽  
Conditional Stability ◽  
Fram Strait ◽  
Seawater Samples ◽  
The One ◽  
Shelf Region ◽  
Ligand Model ◽  
Ligand Group

Competitive ligand exchange – adsorptive cathodic stripping voltammetry (CLE-AdCSV) is a widely used technique to determine dissolved iron (Fe) speciation in seawater, and involves competition for Fe of a known added ligand (AL) with natural organic ligands. Three different ALs were used, 2-(2-thiazolylazo)-p-cresol (TAC), salicylaldoxime (SA) and 1-nitroso-2-napthol (NN). The total ligand concentrations ([Lt]) and conditional stability constants (log K′Fe’L) obtained using the different ALs are compared. The comparison was done on seawater samples from Fram Strait and northeast Greenland shelf region, including the Norske Trough, Nioghalvfjerdsfjorden (79N) Glacier front and Westwind Trough. Data interpretation using a one-ligand model resulted in [Lt]SA (2.72 ± 0.99 nM eq Fe) > [Lt]TAC (1.77 ± 0.57 nM eq Fe) > [Lt]NN (1.57 ± 0.58 nM eq Fe); with the mean of log K′Fe’L being the highest for TAC (log ′KFe’L(TAC) = 12.8 ± 0.5), followed by SA (log K′Fe’L(SA) = 10.9 ± 0.4) and NN (log K′Fe’L(NN) = 10.1 ± 0.6). These differences are only partly explained by the detection windows employed, and are probably due to uncertainties propagated from the calibration and the heterogeneity of the natural organic ligands. An almost constant ratio of [Lt]TAC/[Lt]SA = 0.5 – 0.6 was obtained in samples over the shelf, potentially related to contributions of humic acid-type ligands. In contrast, in Fram Strait [Lt]TAC/[Lt]SA varied considerably from 0.6 to 1, indicating the influence of other ligand types, which seemed to be detected to a different extent by the TAC and SA methods. Our results show that even though the SA, TAC and NN methods have different detection windows, the results of the one ligand model captured a similar trend in [Lt], increasing from Fram Strait to the Norske Trough to the Westwind Trough. Application of a two-ligand model confirms a previous suggestion that in Polar Surface Water and in water masses over the shelf, two ligand groups existed, a relatively strong and relatively weak ligand group. The relatively weak ligand group contributed less to the total complexation capacity, hence it could only keep part of Fe released from the 79N Glacier in the dissolved phase.

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