The voltammetric determination of Mo in seawater after adsorptive accumulation of the Eriochrome Blue Black R complex

1987 ◽  
Vol 65 (5) ◽  
pp. 957-960 ◽  
Author(s):  
S. N. Willie ◽  
S. S. Berman ◽  
J. A. Page ◽  
G. W. VanLoon
Keyword(s):  
Limit Of Detection ◽  
Reference Electrode ◽  
Direct Determination ◽  
Linear Sweep Voltammetry ◽  
Linear Sweep ◽  
Negative Direction ◽  
Seawater Samples ◽  
Certified Values ◽  
A Current

A method for direct determination of molybdenum in seawater has been developed, and uses linear sweep voltammetry after adsorptive accumulation of the Erichrome Blue Black R (EBBR) complex on a static mercury drop electrode. To an acidified (pH 1.6) seawater (SW) sample, 6.0 × 10−6 M EBBR is added and preconcentration by adsorption is carried out for 30 s at a potential of −0.05 V vs. the Ag/AgCl/SW reference electrode. The potential is then scanned in the negative direction, giving a current peak for the reduction of the Mo—EBBR complex at −0.17 V. Under these conditions the limit of detection is 0.50 ng/mL. Experimental results for Mo in seawater using this technique agree well with certified values for two reference seawater samples (NASS-1, CASS-1).

The cathodic reduction of PbO in the passive layer on lead in aqueous sulphuric acid

1984 ◽  
Vol 62 (3) ◽  
pp. 596-600 ◽  
Author(s):  
R. G. Barradas ◽  
D. S. Nadezhdin
Keyword(s):  
Experimental Data ◽  
Three Dimensional ◽  
Reference Electrode ◽  
Linear Sweep Voltammetry ◽  
Passive Layer ◽  
Cathodic Reduction ◽  
Linear Sweep ◽  
Current Time ◽  
Lead Monoxide ◽  
Two Peaks

The cathodic reduction of the lead monoxide layer formed on lead in 30% aqueous H2SO4 under anodic oxidation at 0.6 V (vs. Hg/HgSO4 reference electrode) was investigated by linear sweep voltammetry, potential step and admittance measurements. The experimental data were analyzed respectively in terms of thin-layer electrochemistry, electrocrystallisation, and changes of resistance of the PbO layer under reduction. The results seem to be best interpreted from the theory of three-dimensional electrocrystallisation as PbO is reduced to Pb. At sub-zero temperatures the PbO peak observed on our voltammograms and potentiostatic current time transients reveals the splitting of the curves into two peaks, which may be a result of reduction of the same material but of different phases, namely, orthorhombic and tetragonal PbO.

Determination of Cholesterol by p-Nitrobenzoate Derivatization and Liquid Chromatography

1994 ◽  
Vol 77 (5) ◽  
pp. 1190-1196 ◽  
Author(s):  
Thomas W Hamill ◽  
Abdel M Soliman
Keyword(s):  
Dairy Products ◽  
Isopropyl Alcohol ◽  
Methylene Chloride ◽  
Limit Of Detection ◽  
Lipid Extraction ◽  
Diode Array ◽  
Gas Chromatographic Method ◽  
Certified Values ◽  
Peak Purity

Abstract The method involves direct saponification and formation of the sterol p-nitrobenzoate (PNB) derivatives or lipid extraction with methylene chloride and isopropyl alcohol, saponification, fatty acid methylation, and formation of the sterol PNB derivatives. The sterol PNB derivatives are separated on a C8 column with a mobile phase of acetonitrile-hexane-water (250 + 30 + 3) and quantitated by UV detection at 280 nm. The limit of detection for cholesterol is 2 ng. The response was linear over a range of 4 to 250 ng (r = 0.999). Assays of NIST SRM 1845 and 1563 by this method gave results that were closer to the certified values than were results obtained by the AOAC gas chromatographic method. Reproducibility was evaluated by using foods containing low, medium, and high levels of cholesterol. The % coefficient of variation ranged from 1.8 to 6.7. Studies on a wide variety of food products (using lipid extraction and saponification-methylation) gave a mean recovery of 87.5 ± 10.1%. Direct saponification of poultry and dairy products gave a mean recovery of 101.3 ± 15.8%. Peak purity was determined by diode array spectrophotometry.

Anodic Voltammetric Behavior of Lincomycin and its Electroanalytical Determination in Pharmaceutical Dosage form and Urine at Gold Electrode

2017 ◽  
Vol 231 (5) ◽  
Author(s):  
Jyothi C. Abbar ◽  
Manjunath D. Meti ◽  
Sharanappa T. Nandibewoor
Keyword(s):  
Gold Electrode ◽  
Dosage Form ◽  
Oxidation Process ◽  
Linear Sweep Voltammetry ◽  
Linear Sweep ◽  
Experimental Conditions ◽  
Pharmaceutical Dosage Form ◽  
Antibiotic Drug ◽  
Voltammetric Behavior

AbstractThe anodic voltammetric behavior of an antibiotic drug, lincomycin hydrochloride (LIN) at gold electrode (GE) has been investigated using cyclic and linear sweep voltammetry. The dependence of the current on pH, concentration and scan rate were investigated to optimize the experimental conditions for the determination of lincomycin. The anodic peak was characterized and the process was adsorption-controlled. The number of electrons transferred in the oxidation process was calculated. In the range of 8.0×10

Determination of Rate and Equilibrium Constants for the Reactions between Electron Transfer Mediators and Proteins by Linear Sweep Voltammetry

1997 ◽  
Vol 249 (2) ◽  
pp. 212-218 ◽  
Author(s):  
Vernon D. Parker ◽  
Alisa Roddick ◽  
Lance C. Seefeldt ◽  
Haijiang Wang ◽  
Gang Zheng
Keyword(s):  
Electron Transfer ◽  
Equilibrium Constants ◽  
Linear Sweep Voltammetry ◽  
Linear Sweep

Gas Chromatographic Determination of Pentachlorophenol in Gelatin

1984 ◽  
Vol 67 (2) ◽  
pp. 275-277
Author(s):  
Arnold P Borsetti ◽  
Lee S Thurston
Keyword(s):  
Gas Chromatography ◽  
Liquid Phase ◽  
Electron Capture ◽  
Limit Of Detection ◽  
Direct Determination ◽  
Chromatographic Determination ◽  
Gelatin Matrix ◽  
Limit Of Quantitation ◽  
Acetate Derivative

Abstract A method is described for the determination of pentachlorophenol (PCP) in gelatin. The method employs acid and heat to hydrolyze the gelatin matrix, a base partition and wash for separation and cleanup, and a reacidification and extraction with hexane for direct determination of PCP, without preparation of a derivative, using gas chromatography (GC) with a 1% SP-1240DA liquid phase and a 63Ni electron capture detector. Recoveries averaged 106% for fortifications between 0.02 and 1.0 ppm. The limit of quantitation is 20 ppb. The limit of detection is 4-6 ppb. The method, which has undergone a successful intralaboratory trial, is simple and rapid, and requires only general laboratory reagents and equipment. GC of the acetate derivative of PCP is used for confirmation of identity.

Polarographic determination of azobenzene

1986 ◽  
Vol 51 (1) ◽  
pp. 25-33 ◽  
Author(s):  
Jiří Barek ◽  
Roman Hrnčíř
Keyword(s):  
Detection Limit ◽  
Electrode Surface ◽  
Linear Sweep Voltammetry ◽  
Polarographic Determination ◽  
Hanging Mercury Drop Electrode ◽  
Linear Sweep ◽  
Aqueous Methanol ◽  
Mercury Drop Electrode

Conditions were found for the determination of azobenzene by means of DC, AC, TAST, DP, and FSDP polarography and linear sweep voltammetry on a hanging mercury drop electrode in the medium of aqueous methanol, which ensures a sufficient solubility of azobenzene. In the latter two methods, the detection limit was around 10-8 mol/l; a still lower value could be attained by preliminary accumulation of azobenzene, i.e. adsorption on the electrode surface.

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