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At least 73 records · Page 4Linked to original sources
PubMed2003

Differential pulse polarography: a method for the direct study of biosorption of metal ions by live bacteria from mixed metal solutions.

The technique of differential pulse polarography is shown here to be applicable to the monitoring directly the biosorption of metal ions from solution by live bacteria from mixed metal solutions. Biosorption of Cd(II), Zn(II) and Ni(II) by P. cepacia was followed using data obtained at the potential which is characteristic of the metal ion in the absence and presence of cells. Hepes buffer (pH 7.4, 50 mM) was used as a supporting electrolyte in the polarographic chamber and metal ion peaks in the presence of cells of lower amplitude were obtained due to metal-binding by the cells. Well defined polarographic peaks were obtained in experiments involving mixtures of metal ions of Cd(II)-Zn(II), Cu(II)-Zn(II), Cu(II)-Cd(II) and Cd(II)-Ni(II). Biosorption of Cd(II), Zn(II) increased with solution pH. The method was also tested as a rapid technique for assessing removal of metal ions by live bacteria and the ability of the polarographic technique in measuring biosorption of metal ions from mixed metal solutions is demonstrated. Cu(II) was preferentially bound and removal of metals was in the order Cu(II) > Ni(II) > Zn(II), Cd(II) by intact cells of P. cepacia.

Adsorption↗
PubMedDate not supplied

Sweep potential polarography and multiwire surface tissue electrodes.

A multitipped seven barrelled platinum electrode for brain surface oxygen measurements during neurosurgery is described. Its performance has been examined when employed under conditions of sweep potential polarography. Although there is no plateau within the oxygen polarogram, the electrode displays linear performance within the physiological range, gives reproducible results in practice, has an acceptable temperature coefficient and a fast response time.

Cerebral Cortex↗
PubMed1983

Pulse polarography and intravascular oxygen electrodes.

The membranes covering standard polarographic in vivo PO2 electrodes were modified with a view to altering their response times. Their performance was examined under constant and pulsed polarization. Pulse polarization diminished the under-reading of the PO2 signal which occurred at low flow rates. The stability of the electrode signal was greatly improved by integrating the electrode current over the pulse period. The combination of thin membranes and pulsed polarography will provide a PO2 electrode with a fast time response without under-reading the true in vivo PO2.

Electrodes↗
PubMed1979

Immunoassay by differential pulse polarography.

An immunological method based on labeling an antigen with an electroactive group detectable by differential pulse polarography has been demonstrated. Estriol labeled with mercuric acetate is electroactive, giving a reduction wave at -300 millivolts versus a standard calomel electrode. Addition of estriol antibody to 4-mercuric acetate estriol diminishes the peak current as a result of the antigen-antibody binding reaction. Separation of free-labeled estriol from antibody-bound-labeled antigen is unnecessary. The method is potentially useful as an analytical immunological technique.

Estriol↗
PubMed1992

[Studies on secondary derivative differential pulse polarography and its applications].

Secondary derivative differential pulse polarography was developed and used for the quantitative analysis of ribostamycin sulfate, kanamycin and their preparations. By using sodium hydroxide-potassium dihydrogen phosphate solution as the base solution, ribostamycin sulfate and kanamycin showed good peaks at 0.105 V and -0.37 V (vs Ag/AgCl) respectively. The linear relationship of ribostamycin sulfate and kanamycin between concentration and peak height was obtained in the concentration range of 1.8-10.8 x 10(-4) mol/L and 3.1-18.6 x 10(-4) mol/L and the determination limit was 7.2 x 10(-9) mol/L and 4.6 x 10(-8) mol/L respectively. This method is simple, rapid and sensitive. The result is accurate.

Kanamycin↗
PubMed2006

[Inclusion of coenzyme Q10 with beta-cyclodextrin studied by polarography].

AIM: To investigate the inclusion of coenzyme Q10 with beta-cyclodextrin (beta-CD). METHODS: The inclusion of the electroactive guest molecule coenzyme Q10 with the host molecule beta-CD was studied by the polarography. The change of the reduction peak current of the inclusion complex with time and the change of the peak potential of the inclusion complex with beta-CD concentration were examined. In order to study the photostability, the change of the reduction peak current of both coenzyme Q10 and coenzyme Q10-beta-CD inclusion complex with time were also examined under light, separately. RESULTS: In 0.1 mol x L(-1) HAc/NaAc (pH 4.7) buffer-ethanol/water (60:40) medium, coenzyme Q10 was included with p-CD to form an 1:1 inclusion complex. The formation constant Kf was 1.26 x 10(4) L x mol(-1) the apparent formation rate constant was 6.64 x 10(-2) min(-1). The photodegradation apparent rate constant of coenzyme Q10 as 7.77 x 10(-3) min(-1) and that of the coenzyme Q10-beta-CD inclusion complex was 3.38 x 10(-3) min(-1). CONCLUSION: The inclusion of coenzyme Q10 with beta-CD took place. The stability of coenzyme Q10 to lights was improved in a certain degree due to the formation of the inclusion complex.

Coenzymes↗
PubMed1975

Application of pulse polarography with anodic stripping voltammetry to biological and toxicological analyses for lead and cadmium.

The development of polarographic techniques within the last thirty years has made possible exceptional increases in sensitivity ; thus the order of concentration studied has passed from 10-3 g ion/1. to 10-10 g ion/1. Pulse polarography with anodic stripping voltammetry is, therefore, particularly suitable for the determination of a large number of the so-called " biologically essential " and " highly toxic " metals, more often than not present in extremely low concentrations in biological samples which may be of limited volume (blood, for example). Our principal concern has been to describe and apply a method for the determination of lead and cadmium, sufficiently sensitive, precise, practical and rapid for everyday use by biologists and toxicologists. A fortiori this method is applicable in hydrology to the determination of traces of these metals in water.

Cadmium↗
PubMed1989

Determination of avicularin in Polygonum aviculare L. by square wave polarography.

A method for the determination of avicularin in Polygonum aviculare L. is described. Square wave polarography (SWP) with a static mercury drop electrode was used to observe the reduction of avicularin. The supporting electrolyte was an acetate buffer solution of pH 4. Avicularin gives a well-defined peak at a potential of -1.30 V (vs. Ag/AgCl). An excellent linear relationship was obtained between the concentration (1.20-3.59 x 10(-6) mol/L) and peak current. The method can be used to analyze small amounts of sample.

Drugs, Chinese Herbal↗
PubMedDate not supplied

Determination of sulfites in foods by simultaneous nitrogen purging and differential pulse polarography.

An improved technique has been developed for determination of sulfites in food by differential pulse polarography. A Teflon sleeve is fitted to the dropping mercury electrode capillary so that SO2 is purged from the sample and simultaneously detected at peak potential. Bound sulfite in the sample is released at room temperature by addition of base in the absence of oxygen. For some foods, the prepared sample was passed through a Sep-Pak C-18 cartridge to remove naturally occurring sulfur compounds so that only added sulfite is measured. The level of detection was approximately 1 microgram SO2/g. Results agreed with those obtained by the optimized Monier-Williams method for a variety of foods.

Food Analysis↗
PubMed1978

[Qualitative and quantitative determination of amino-2 benzimidazole in aqueous medium by polarography (author's transl)].

Amino-2 Benzimidazole, a residue of the decomposition of some fungicides (Benomyl, Carbendazine, Thiophanate, Methylthiophanate), is measured by polarography in aqueous medium, with a platinium rotating electrode, for the exploration in potentials from +0.5 v to 1.4 v. The best conditions for the quantitative determination are investigated, the study according to pH is performed and the standard curve is given for concentrations from 10(-5) to 10(-3) M/l. The interaction of elementts found in tap water and in aquarium water is also investigated.

Benzimidazoles↗
PubMed1978

[Estimation of mescaline and pellotine in Lophophora coulter plants (Cactaceae) by means of the oscillographic polarography].

Oscillographic polarography has been applied for the mescaline and pellotine estimation. These alkaloids produce in 0.5 N NaOH electrolyte a sharp peak within the cathode region of the oscillogram, each of them showing different potential. It makes possible to estimate them at a concentration of 5.10(-6) g/ml. All the forms of Lophophora williamsii were found to contain mescaline and lower content of pellothine, L. jourdaniana--to have equal content of both alkaloide, L. diffusa and L. fricii--to contain pellotine and only traces of mescaline. Plants grown in the greenhouse accumulated the same amount of alkaloids as native plants. Grafting on roodstock which does not produce essential amount of the alkaloids, does not affect the ability of Lophophora to synthesize mescaline and pellotine.

Alkaloids↗
PubMedDate not supplied

[Identification of coenzyme B12 and other natural cobalamins by polarography].

AdoCbl, MeCbl and OH-Cbl were studied by methods of polarography and three-angle scan voltammetry. Cobalamines studied show a specific electrochemical activity that can be taken as a basis for their identification after separation and purification. The high sensitivity of the method allows to carry out the quantitative analysis of AdoCbl at concentrations ranging from 10(-6) M to 10(-4) M.

Cobamides↗
PubMed1982

Electrochemical investigation of hapten-antibody interactions by differential pulse polarography.

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.

Antibodies, Monoclonal↗
PubMed1980

[Determination of cadmium concentration in the air of a battery manufacturing plant by the method of alternating current polarography].

Concentrations of cadmium at 9 selected workplaces were measured for 3 years. Cadmium was determined by squarewave polarography. Results ranged between 0.024 mg/m3--0.737 mg/m3 (mean concentrations). The highest concentrations occurred at cadmium electrodes production for strip plate batteries. The study of cadmium concentration along with medical examinations allowed to specify how far Vitamin C administration might affect the health status of cadmium--exposed workers.

Air Pollutants↗
PubMed1977

Application of A. C.-polarography in a study of p-nitroanisole metabolism and its kinetic properties.

Phase sensitive alternating current polarography was introduced for the simultaneous determination of p-nitroanisole and its metabolites p-nitrophenol and p-nitrocatechol in kinetic studies with rat liver microsomes. The substrate p-nitroanisole disappears rather rapidly while p-nitrophenol is formed. First traces of a second oxidation product, p-nitrocatechol, can be detected only after a few minutes after the initiation of the reaction. This suggest that O-demethylation of p-nitroanisole is the primary reaction which is followed by aromatic ortho hydroxylation of p-nitrophenol. After incubation times longer than 15 minutes, appreciable amounts of p-nitrocatechol are found which shows optical absorption characteristics similar to those of p-nitrophenol (absorption maximum at 440 nm). It is concluded from these kinetic experiments that optical determination of the primary metabolite during the initial reaction phase constitutes a reliable measure of microsomal O-demethylation activity. Phenobarbital induction differentially increases O-demethylation and ring-ortho-hydroxylation activities. From this and respective inhibition studies it is concluded that possibly multiple forms of cytochrome P-450 are involved in the metabolism of either p-nitroanisole or p-nitrophenol.

Animals↗
PubMedDate not supplied

Electrochemical studies of some quinolone antibiotics. Part II. Determination by differential pulse polarography in substance and in pharmaceutical formulations.

Differential pulse polarography was used to study quinolone antibiotics: ciprofloxacin, enoxacin, norfloxacin, ofloxacin and pefloxacin on a mercury electrode. The optimal parameters and background solutions have been chosen. New polarographic method of quinolone determination in pure form and pharmaceutical formulations was found. Statistical analysis of the results obtained showed that proposed method is of good accuracy and precision.

Anti-Infective Agents↗
PubMed1996

[Determination of lead in blood by polarography].

A method for determination of trace lead in blood with complex catlysis polarography was develop. The peak potential of lead is -0.54 V in the system of hydrochloric acidpotassium iodide-vanadium (IV)-ethanol-ascorbic acid. There is good linelar relationship between peak current and lead concentration in the range of 0-1.0 microgram/3 ml. The recoveries of spiked samples ranged from 76.0% to 105.0% and the average recovery was 91.0% with RSD of 3.6% to 7.0%. The detection limit was 45 micrograms/L. The blood samples of 24 normal people and 6 workers with occupational exposure to lead were measured and the results were concordant with the clinical diagnoses. The proposed method is simple, rapid, sensitive and reliable. It is suitable for determination of trace lead in blood.

Humans↗