Showing papers on "Polarography published in 1982"
TL;DR: In this paper, a critical evaluation of adsorptive accumulation in stripping analysis, with differential pulse polarography for the measurement step, is described, and generally applicable conditions for this method are given.
126 citations
TL;DR: An electrochemical method based on the measurement of the capacity current at the hanging mercury drop electrode by alternating-current polarography was developed and applied to the analysis of surface-active substances in seawater and in sea-surface microlayer samples.
Abstract: An electrochemical method based on the measurement of the capacity current at the hanging mercury drop electrode by alternating-current polarography was developed and applied to the analysis of surface-active substances in seawater and in sea-surface microlayer samples. Surfactant activities of natural samples collected in the Adriatic Sea in 1978–1980 are compared with different model surfactants (Triton-X-100, albumin, fatty acid, humic acid, polysaccharide) and with parallel measurements by the polarographic maximum method. The shape of the capacity current-potential curves of natural samples indicates that the adsorption effect at the electrode is produced predominantly by high molecular weight compounds. The surfactant activity corresponds to about 0.01–0.5 mg·liter−1 for bulk seawater and 0.1–2 mg·liter−1 for sea-surface microlayer samples, relative to Triton-X-100. Seasonal variations in surfactant activity values at offshore stations were related to biological activity.
110 citations
TL;DR: In this article, the 6amino group of adenine was found to be the binding site of 1-methyl-6-aminopurine and its methylated derivatives.
Abstract: : Adenine and its methylated derivatives, 1-methyl-6-aminopurine, 3-methyl-6 aminopurine, N-methyl-6-aminopurine, and N,N-dimethyl-6-aminopurine, were studied in alkaline solution by DC, normal pulse and differential pulse polarography and by cyclic voltammetry and cathodic stripping voltammetry at hanging mercury drop electrodes. All save N, N-dimethyl-6-aminopurine gave polarographic mercury drop electrodes. All save N, N-dimethyl-6-aminopurine gave polarographic currents anc cathodic stripping peaks due to the formation of slightly soluble compounds with mercury. It was concluded that the 6-amino group of adenine is the mercury binding site in these cases. Cathodic stripping behavior suggests that 1-methyl-6-aminopurine, 3-methyl-6-aminopurine, and N-methyl-6-aminopurine can be determined by cathodic stripping voltammetry, and that detection limits for N-methyl-6-aminopurine are comparable to those for adenine (10 to the minus 9th power M). (Author)
60 citations
TL;DR: In this paper, a flow injection analyzer for students, teaching and research (FIAstar) is used in conjunction with a new micropool mercury flow-through electrode, to explore the possibilities offered by using d.c. polarography, rapid scan and amperometric titrations on a dispersed sample zone in motion.
53 citations
TL;DR: In this article, a pulse polarographic study of low-potential electron-transferring proteins at the mercury electrode was performed, and it was observed that the reduction efficiency of these proteins reaches an optimum when the net charge of the protein times its ccncentration is about equal to the same amount of opposite charges, which was added as a polymer or surfactant.
52 citations
TL;DR: A polarographic method has been developed for the determination of formaldehyde in workplace air using midget fritted glass bubblers containing an aqueous solution of 10% methanol to form a formaldehyde hydrazone compound.
Abstract: A polarographic method has been developed for the determination of formaldehyde in workplace air. Samples are collected in midget fritted glass bubblers containing an aqueous solution of 10% methanol. The collected formaldehyde in the absorbent solution is derivatized with hydrazine reagent to form a formaldehyde hydrazone compound. An aliquot of the resulting solution is analyzed by differential pulse polarography at a dropping mercury electrode. The sample generation system, impinger collection, polarographic analysis, and precision and accuracy data are described. The method was validated over the range of 5.8 to 17.7 mg/cu m, which corresponds to 0.5 to 2 times the (peak) OSHA-PEL for a 30-liter sample at a flow rate of 1 Lpm. The average recovery was 103%. The pooled coefficient of variation or relative standard deviation was 0.08.
46 citations
TL;DR: In this paper, explicit expressions for NPP limiting current densities influenced by reactant adsorption are derived for two cases: (1) a linear NPP and (2) a lin
44 citations
TL;DR: In this article, a study of some properties of Pb(II) in solutions of sulphuric acid was carried out by means of differential pulse polarography, and the range of concentrations of acid extended from 0.6 to 70 weight % of H 2 SO 4 (0.06-11.5 M).
41 citations
TL;DR: The differential pulse polarography of Ge(IV, Sn(IV), As(V, Sb(V), Se(IV) and Te(VI) has been investigated in perchlorate media containing catechol using a static mercury drop electrode.
38 citations
TL;DR: The binding of electroactively labeled estriol with estrogen-specific antibody and its subsequent displacement by unlabeled Estriol have been monitored by differential pulse polarography, indicating competitive and reversible binding of the two ligands for the antibody.
Abstract: The binding of electroactively labeled estriol with estrogen-specific antibody and its subsequent displacement by unlabeled estriol have been monitored by differential pulse polarography. Estriol was found to be electro-inactive in the potential range -200 mV to -1000 mV vs a silver/silver chloride electrode. Estriol labeled in the 2 and 4 position with nitro groups was electroactive, giving two reduction waves at -422 mV and -481 mV vs a silver/silver chloride electrode. The peak current was linear with concentration over the range 60 micrograms/L to 3.7 mg/L. The addition of aliquots of estrogen-specific antibody reduced the peak current proportionately, indicating the binding of ligand to specific antibody. Subsequent addition of unlabeled estriol produced incremental increases in peak reduction current, indicating competitive and reversible binding of the two ligands for the antibody. Separation of bound from free labeled hapten was not necessary because reduction of the antibody-bound labeled estriol is attenuated at the electrode.
36 citations
TL;DR: Differential pulse voltammetry of cytochrome c 553 from Desulfovibrio vulgaris Hildenborough shows the existence of a reduction peak at E p ≈ −0.20 V (vs. Ag/AgCl reference electrode) as mentioned in this paper.
TL;DR: In this article, the inhibition of the electrode reaction of Cd(II) in seawater as supporting electrolyte in the presence of the non-ionic surfactant T-X-100 was studied by differential pulse polarography in a wide concentration range of surfactants (10 −7 −5×10 −4 mol dm −3 ).
TL;DR: In this article, the inhibitory effect of three homologous dialkyl-phenyl-phosphine oxides (C 6 H 5 (R) 2 ) PO; R=C 2 H 5, C 3 H 7, C 4 H 9 ) on the Cu 2+ discharge reaction at a fully covered dropping mercury electrode has been investigated by the polarographic technique.
TL;DR: In this article, the advantages of the current-scan method over the potential scan method are discussed and a simple device for the compensation of the ohmic potential drop is proposed, which has been found to be favorable in the voltammetric study on the ion transfer across the aqueous/organic solutions interface.
Abstract: The current-scan method has been found to be favourable in the voltammetric study on the ion transfer across the aqueous/organic solutions interface, and successfully applied to the polarography with the aqueous electrolyte dropping electrode. The advantages of the current-scan method over the potential-scan method are discussed. A simple device for the compensation of the ohmic potential drop is proposed.
TL;DR: In this paper, a set of data for trace cadmium diffusing in mercury amalgams has been produced over the temperature range 283-333 K and for zinc at 298 K. The classical open-ended capillary technique has been used for both sets of measurements.
TL;DR: A comparison of gas-liquid chromatography, differential-pulse polarography and a colorimetric method for the determination of nitrilotriacetic acid in settled sewage, sewage effluent, potable water, soil extracted water and deionised water has been undertaken.
Abstract: A comparison of gas-liquid chromatography, differential-pulse polarography and a colorimetric method for the determination of nitrilotriacetic acid in settled sewage, sewage effluent, potable water, soil extracted water and deionised water has been undertaken. Differential-pulse polarography has also been applied to the determination of nitrilotriacetic acid in saline samples. By statistical analysis of replicate determinations, accuracy and precision have been evaluated, and calibration linearity assessed. Interferences were observed for sewage samples when analysed by all three methods. Precision was generally higher for differential-pulse polarography down to 100 μgl−1, although only gas-liquid chromatography is applicable to concentrations below 25μgl−1 in non-saline samples. The colorimetric method was not applicable to concentrations below 500 μgl−1 of nitrilotriacetic acid.
TL;DR: In this paper, a polarographic and kinetic study of the reduction of diacetyl has been carried out in the 0 < pH < 10 range in buffered aqueous solutions.
TL;DR: In this paper, a microprocessor-based waveform generator was used to optimize the electrochemical detection of ethynyloestradiol and laevonorgestrel, which was applied to pharmaceutical formulations; the data obtained agree satisfactorily with the nominal contents.
TL;DR: In this paper, a fast-scan modification of differential pulse polarography (d.p.) is described, in which a dropping mercury electrode with a drop lifetime of 50 s is polarized by 100-ms pulses with a 100ms interval between pulses; sampling and treatment of the current data are the same as in d.p.
TL;DR: In this article, the electrode reaction of Ni(II)/Ni(Hg) system occurring in 4−13.7 mol kg−1 solutions of Ca(ClO4)2 in the temperature range 20−185°C was studied by means of pulse polarography and cyclic voltammetry.
TL;DR: In this paper, the behavior of solute ions at the interface between aqueous and organic phases is clearly demonstrated by the current-scan polarography at the electrolyte dropping electrode, and the potential-generating process at the liquid membrane type ion-selective electrode is explained on the basis of the polarographic results.
Abstract: The behavior of solute ions at the interface between aqueous and organic phases is clearly demonstrated by the current-scan polarography at the electrolyte dropping electrode. The potential-generating process at the liquid membrane type ion-selective electrode is explained on the basis of the polarographic results.
TL;DR: In this paper, the ion pair formation effects of metal ions on the electroreduction of p-quinones in N,N-dimethylformamide were studied systematically by polarography, and the formation constants of 1 : 1 and 1 : 2 associates, as evaluated by the 1/F02-weighted least squares method, decrease with increase in the anion size.
Abstract: Ion pair formation effects of metal ions on the electro-reduction of p-quinones in N,N-dimethylformamide were studied systematically by polarography The formation constants of 1 : 1 and 1 : 2 associates, as evaluated by the 1/F02-weighted least squares method, decrease with increase in the anion size
TL;DR: In this article, a method for the determination of metronidazole in pharmaceutical tablets is presented, which is demonstrated to be simple, rapid, linear, reproducible and accurate.
Abstract: A method for the determination of metronidazole in pharmaceutical tablets is presented. Differential pulse polarography at a static mercury drop electrode is used to observe the reduction of the imidazole. The method is demonstrated to be simple, rapid, linear, reproducible and accurate.
TL;DR: In this article, the equipment and procedure for the determination of heavy metals based on dc anodic stripping voltammetry at a rotating ring was described, and the results were compared with the theoretical considerations given by de Vries and van Dalen for a stationary mercury film electrode and by Bakanov et al. for a rotating film electrode.
TL;DR: In this paper, the best system for determining methionine is: 2 × 10−4M nickel(II)-0.06 M disodium tetraborate-nitric acid (pH 8.6).
Abstract: Methionine yields a nickel(II) catalytic polarographic pre-wave in borate media. This pre-wave was studied as a function of the composition and pH of the borate medium, the nickel(II) concentration, the addition of neutral salts and the methionine concentration. The best system for determining methionine is: 2 × 10–4M nickel(II)-0.06 M disodium tetraborate-nitric acid (pH 8.6). D.c. polarography is suitable for the determination of methionine over the concentration range 1 × 10–5–8 × 10–5M. In differential-pulse polarography the calibration graph is linear over the methionine concentration range 3 × 10–6–55 × 10–6M.
TL;DR: In this article, a method for quantitative trace level analysis of selenium in fish tissues using differential pulse polarography at a dropping mercury electrode (DME) is described, which is a simple, quick, sensitive, and cost effective technique for routine quantitative determination of fish tissues.
Abstract: A method is described for the quantitative trace level analysis of selenium in fish tissues using differential pulse polarography at a dropping mercury electrode (DME). Advantages of the method include high sensitivity (detection limit = 5μg/1), linear response over a wide range of concentrations (5 μg/l ‐ 20 mg/l), close precision among replicate analyses, and freedom from interfering elements. No pre‐concentration is necessary and both calibration and analysis of a number of samples can be done in a matter of minutes. The differential pulse‐DME method is a simple, quick, sensitive, and cost effective technique for routine quantitative determination of selenium in fish tissues.
TL;DR: Differential pulse polarography is used in a rapid-flow analysis system for automated determination of lead, zinc and ascorbic acid in acetate-buffered sample solutions, without the need for sample deaeration.
TL;DR: In this paper, the reduction of nitrate at mercury electrodes in the presence of Yb(III) was studied using differential pulse polarography, cyclic voltammetry and coulometry.
TL;DR: In this paper, an Ag/Ag+ this paperERENCE electrode in ethanolic solution was investigated and a method of ethanol purification for electrochemical purposes was also presented, where simple preparation, fast response and high exchange current density characterize this electrode.
Abstract: An investigation of an Ag/Ag+ REFERENCE electrode in ethanolic solution is reported. Simple preparation, fast response and high exchange current density characterize this REFERENCE electrode. A method of ethanol purification for electrochemical purposes is also presented.
TL;DR: In this article, the performance of a flow-through polarographic detector for HPLC was evaluated using a single-layer differential capacity (C) with the lateral interaction parameter in the limits 0.4 ≤a ≤ 1.0.
Abstract: Specific adsorption of cholanoic acids (cholic, hyodeoxycholic, deoxycholic, lithocholic and chenodeoxycholic acid) was studied in methanol + 0.2 M acetic buffer, (pH 4) at the dropping mercury electrode (DME) by alternating voltage (a. v.) and alternating current (a. c.) polarography. The usefulness of both techniques for detection in reversed phase high-performance liquid chromatography (HPLC) was evaluated using a previously developed flow-through polarographic detector. The adsorption of all acids at the DME could be described by the Frumkin isotherm deduced from the data on electrical double layer differential capacity (C) with the lateral interaction parameter (a) in the limits 0.4 ≤a ≤ 1.2 in 80 % CH3OH + 20 % 0.2 M acetic buffer (pH 4). When examining the theoretical Frumkin isotherms constructed for a values in the limits −1 ≤a ≤ 2.5 and the ratio of capacity at maximum DME coverage with the acid (C 1) to the capacity at zero coverage (C 0) C 1/C0=1/3, it appeared that polarographic detection for HPLC based on C variations is advantageous for 0 ≤ a ≤ 1.0. The dependence of the signal due to the change in C resulting from the presence of cholic acid on the concentration of the acid in the bulk of the solution was more useful for analytical purposes for a. v. than a.c. polarographic response. For cholic acid as for many other systems the adsorption becomes weaker and a decreases with increasing organic solvent content in the mixture. The combined effect of CH3OH on both isotherms of adsorption at DME and on the Chromatographic retention parameters results in much smaller decrease of sensitivity of the detector than could be predicted when examining solely changes in the slope of increasing parts of the adsorption isotherms.