SEARCH · PubMed Health

Results for “POLAROGRAPHY”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 775 records · Page 43Linked to original sources

PubMed1975

[Polarographic determination of some phenylsubstituted anticonvulsants].

A method is described to determine the anticonvulsive drugs phenobarbital, phenytoin, mephenytoin, methylphenobarbital and primidone. A serum extract is nitrated, separated by thin-layer chromatography, and the nitro compounds are determined by polarography. The rates of recovery are: phenobarbital 81%, phenytoin 79%, mephenytoin 80%, methylphenobarbital 86% and primidone 84%. The sensitivity limits range from 3.5 mug/ml plasma for phenytoin to 5.5 mug/ml for mephenytoin and methylphenobarbital. This method might be useful not only for determination of therapeutic blood levels but also for toxicology because it saves time and the expenditure of work is small. The mean deviation for mononitrated anticonvulsive drugs is +/- 2.8% (for 50 mug/ml) and +/- 11.6% (for 10 mug/ml). For phenytoin being dinitrated, the values are +/- 0.6% and +/- 7.5% for 50 mug and 5 mug, respectively). We determined blood levels of out-patients containing phenobarbital and phenytoin besides other substances. Having once established calibrating curvers internal or external standards are not required.

Anticonvulsants↗

PubMed1998

[Study on voltammetric behaviour of clozapine and its single-sweep oscillopolarography].

A sensitive reduction peak of clozapine is obtained by single-sweep oscillopolarography in 0.1 mol.L-1 H2SO4 solution. The peak potential is -0.95 V (vs. SCE). The peak current is directly proportional to the concentration of clozapine with a detection limit of 2.0 x 10(-8) mol.L-1. The voltammetric behaviour of clozapine and its mechanism of electrode reaction have been studied by linear-sweep and cyclic voltammetry and pulse polarography etc. The reduction process is irreversible with adsorptive characteristics. The number of electrons transferred n is 2. The electron transfer coefficient alpha is 0.62. Its behaviour obeys Langmuir adsorption isotherm. The adsorption coefficient beta is 1.91 x 10(6) L.mol-1. The energy of adsorption delta G0 = -35.83 kJ.mol-1. The method has been applied to the determination of clozepine in tablet and urine.

Antipsychotic Agents↗

PubMedDate not supplied

Differential pulse polarographic determination of lead in complex materials after adsorption of its N-methylethylxanthocarbamate complex on microcrystalline naphthalene or on N-methylethylxanthocarbamate-benzyldimethyltetradecylammonium-naphthalene adsorbent.

Lead is quantitatively adsorbed as the lead N-methylethylxanthocarbamate (MEXC)-benzyldimethyltetradecylammonium (BDTA) ion pair complex on microcrystalline naphthalene in the pH range 4.0-11.0. The metal is desorbed with HCI and determined by differential pulse polarography. Alternatively lead can be quantitatively adsorbed on the adsorbent (MEXC-BDTA-naphthalene) packed in a column at a flow rate of 1-2 mL/min and determined similarly. Dissolved oxygen is removed by adding a few milliliters of 4% NaBH4 solution. The detection limit is 0.12 microg/mL at the minimum instrumental settings (signal-to-noise ratio, 2). Linearity was obtained over the concentration range 0.3-20.0 microg/mL with a correlation factor of 0.9998 and a relative standard deviation of +/- 0.98%. Various parameters, such as the effect of pH, volume of aqueous phase, flow rate, and the interference of a large number of metal ions and anions, were studied in detail to optimize the conditions for the trace determination of lead in various standard alloys, standard biological materials, and environmental samples.

Adsorption↗

PubMedDate not supplied

[Mechanism of enzymatic dismutation of superoxide anion-radicals].

The mechanism of interaction of the superoxide radical O2-. with lysine was studied by the methods of polarography and ab initio quantum chemical calculations. It was shown that O2-. interacts with lysine to form a thermodynamically stable complex with proton transfer and formation of the HO2. radical.

Free Radicals↗

PubMed1990

Polarographic and spectrophotometric determination of Nifuroxazide in pharmaceuticals. II. Determination of Nifuroxazide in suspensions.

The properties of Ercefuryl suspensions which contain Nifuroxazide as active constituent were studied by spectrophotometry and polarography. On this basis two analytical methods for determination of Nifuroxazide content in suspensions were devised: one polarographic, based on the electrochemical reduction of the nitro-group, and a spectrophotometric, based on the absorbance measurements at 373 nm.

Anti-Infective Agents↗

PubMed1992

[Polarographic analysis of cobalt in biological specimens].

References to different methods of cobalt detection in biologic material are given. Polarographic detection of cobalt in human urine and animal biologic material worked out by authors was used for evaluation of biologic MAC. Biologic material was limed by nitric and sulfuric acids. Sulfuric acid was carefully distilled off the burnt material. Mineralized material was dissolved in 10 ml of 1N hydrochloric acid, filtered and again steamed into moist salts. 2.5 ml of water, 0.5 ml of dimethylglyoxime (0.02 M), 2 ml of Na4P2O7 (0.2 M) and 5 ml of buffer solution (0.1 M NH4Cl and NH4OH) were added to limed mineral, than pH was driven to 9 by 1 = 2 drops of ammonia solution and after blowing through, the specimen was exposed to polarography in alternating current. ++Redox potential of cobalt is 1.18 V. The method can be used for detection of cobalt in urine of workers contacting with the stated metal. Sensitivity of the method is 0.02 Mkg/ml.

Animals↗

PubMed2004

[Polarograhic adsorptive wave of protein hydrolysate in Pb2+ and sodium hydroxide solution and its application].

AIM: To propose a new simple and sensitive voltammetric method for determination of proteins. METHODS: Protein with sulfhydryl or disulfide bond in 0.5 mol x L(-1) NaOH, 1.5 x 10(-4) mol x L(-1) Pb2+ and 0.02% tetrabutylammonium iodide was heated in boiling water for 5 minutes. The reactive product gave a well defined reductive adsorption wave at -0.66 V (vs SCE) by means of single sweep polarography, and the height of derivative wave was proportional to the concentration of proteins. RESULTS: The peak height was linearly proportional to bovine serum albumin (BSA) or human serum albumin (HSA) concentration in range of 7.5 x 10(-10) -3.0 x 10(-7) mol x L(-1) (r(BSA) = 0.9995, and r(HSA) = 0.9990). The detection limit of BSA or HSA was 3.0 x 10(-10) mol x L(-1). For lysozyme (Lyso), the concentration range was from 1.4 x 10(-8) to 1.3 x 10(-6) mol x L(-10 (r(Lyso) = 0.9997) and the detection limit was 7.0 x 10(-9) mol x L(-1). CONCLUSION: The method is simple, rapid, sensitive and applicable to the assay of diluted human serum albumin samples.

Adsorption↗

PubMed2004

[Polarographic catalytic wave of clarithromycin and its applications].

AIM: To develop a new method for the determination of clarithromycin. METHODS: The catalytic wave of clarithromycin in the presence of K2S2O8 was used for improving the analytical sensitivity. The rapid determination of clarithromycin has been carried out by linear single sweep polarography. RESULTS: The reduction wave of clarithromycin appeared at ca. -0.79 V (vs SCE) in 0.24 mol x L(-1) KH2PO4-Na2HPO4 (pH 6.81) supporting electrolyte, which was ascribed to the reduction of carbonyl group on C-9 position. In the presence of 0.01 mol x L(-1) K2S2O8, the reduction wave was catalyzed to produce a parallel catalytic wave. The peak current of the catalytic wave was ca. Twenty times higher than that of the corresponding reduction wave. Based on the catalytic wave, a new method for the determination of clarithromycin has been proposed. The peak current of the catalytic wave was rectilinear to clarithromycin concentration in the range of 4.0 x 10(-7)-5.0 x 10(-5) mol x L(-1). The detection limit was 2.0 x 10(-7) mol x L(-1). CONCLUSION: The proposed method could be used for the direct determination of clarithromycin in pharmaceuticals and urine without preliminary separation.

Anti-Bacterial Agents↗

PubMed2005

[Polarographic behavior and determination of glimepiride].

AIM: To establish a polarographic method of parallel catalytic hydrogen wave for determination of glimepiride. METHODS: The catalytic wave of glimepiride in the presence of K2S2O8 was used to improve the analytical sensitivity. The rapid determination of glimepiride was done by linear single sweep polarography. RESULTS: The catalytic hydrogen wave of glimepiride was measured at ca. -1.36 (vs SCE) in 0.09 mol x L(-1) Na2B4O7-KH2PO4 (pH 6.24 +/- 0.1) supporting electrolyte. When 1.0 x 10(-2) mol x L(-1) K2S2O8 was present, the current increased by 25 times, and the peak potentioal was unchanged, producing a more sensitive parallel catalytic hydrogen wave. The peak current of the parallel catalytic hydrogen wave was rectilinear to the glimepiride concentration in the range 1.0 x 10(-7) - 4.2 x 10(-5) mol x L(-1) (r = 0.9990, n = 9). The detection limit was 5.0 x 10(-8) mol x L(-1). CONCLUSION: The proposed method could be applied to the determination of glimepiride in pharmaceuticals without preliminary separation.

Catalysis↗

PubMed1992

Mechanism of the polarographic reduction of a new 5-nitrofuran derivative with antibacterial activity.

The reduction at mercury electrodes of a new 5-nitrofuran derivative with antibacterial activity, N2-(5-nitrofurfurylidene)formohydrazide-4-(3,5-dicyanophenyl)-6-ethoxy-2- pyridyl)imide, was studied by conventional, normal pulse, reverse normal pulse and differential pulse polarography in water-dimethylformamide (30%) buffered media. The waves observed, whose number depended on pH, are attributed to the reduction of the nitro group (6 electrons) and the azomethinic unit (4 electrons). The basic mechanisms of the electrode reactions have been deduced from the characteristics of the waves. Conditions for determining the formal potential of the nitroderivative/radical-anion system, a parameter related to pharmacological activity, are also reported.

Anti-Infective Agents↗

PubMed2005

[Parallel catalytic hydrogen wave of acetylspiramycin caused by dissolved oxygen and its application].

AIM: To propose a novel polarographic method for the determination of acetylspiramycin (ASPM) is proposed. METHODS: In 0.1 mol x L(-1) NH4Cl-NH3 x H2O (pH 8.9) buffer containing dissolved oxygen, ASPM yielded a sensitive parallel catalytic hydrogen wave with the peak potential of -1.63 V (vs SCE) by single sweep polarography. RESULTS: The 2nd order derivative peak currents (i(p)") of the parallel catalytic hydrogen waves of ASPM showed a linear relationship with its concentrations in the range from 1.74 x 10(-3) microg x mL(-1) to 3.84 microg x mL(-1) (r = 0.9979, n=13). Its detection limit was 5.80 x l0(-4) microg x mL(-1) (3sigma) and RSD (n=13) was 1.24% at the concentration level of 0.871 microg x mL(-1). CONCLUSION: The proposed method could be applied to the determination of ASPM in ASPM tablets.

Anti-Bacterial Agents↗

PubMed1991

[Transplacental passage of vanadium after treatment with vanadium pentoxide in Wistar rat].

The passage of vanadium pentoxide across the placenta into the embryo/fetus was investigated by analyzing the vanadium content in embryo/fetus at various intervals between 1 h and 48 h after treatment of pregnant Wistar rats with single dose of the V2O5 (5mg/kg) on days 16-18 of gestation, at 4h after treatment of pregnant rats with single dose of V2O5 (5mg/kg) on day 12, and at 120 h after treatment of pregnant rats with dose of V2O5 0.33, 1.0, 3.0 mg/kg on days 6 through 15. The V concentration was determined by catalytic polarography. At after treatment on day 12, the V concentrations in maternal blood, placenta and embryos were elevated in comparison with those of the untreated group. At 4-48 h after treatment on days 16-18, the V concentrations in placenta and fetuses were elevated in comparison with those of the untreated group. The V concentration at 4 h after treatment in various tissues is the highest one among different time points. On days 16-18, 4 h after treatment, the V concentration in placenta was elevated in comparison with that on day 12 of gestation, but the V concentration in embryo/fetus was decreased. At 120 h after treatment on days 6-15, the V concentration in fetus is still high in comparison with that of the untreated group. The V content of fetus varied according to doses, suggesting that embryo/fetus accumulates vanadium. The results showed that vanadium can pass through the placental barrier and enter the embryo/fetus during the embryonal organogenesis in rat, but placenta accumulates vanadium, and the barrier action increases with placental maturity.

Animals↗

PubMed1991

[The species of titanium in natural water].

The species of titanium in natural water was studied. Sample was filtered with a paper filter and a 0.45 micron membrane filter. The content of titanium in each case was determined by polarography proposed by Li, et al. It was found that the main species for all the tested samples was of the particle form. A supernatant of a river water sample was taken to study the effect of pH on the distribution of titanium species. It was found that pH was an important factor for species distribution. At pH1-2, the particle will change into the dissolved form in a short time; at pH 6-8, the dissolved form will change into the particle form in several days.

Hydrogen-Ion Concentration↗

PubMedDate not supplied

[Peroxide modification of skeletal muscle sarcoplasmic reticulum in antioxidant deficiency and under the effect of ionol. II. Physico- chemical properties of the sarcoplasmic reticulum membrane].

Physico-chemical parameters of membranes of skeletal muscles' sarcoplasmic reticulum in antioxidant insufficiency, which was modelled by excluding alpha-tocopherol from the animals ration, and after treatment with phenol antioxidant ionol were studied. It was shown that activation of lipid peroxidation in vitamin E insufficiency results in a significant lowering of microviscosity of lipid bilayer membranes of sarcoplasmic reticulum. Using polarography significant changes in membrane protein conformation were revealed, which were characterized by lowering of integrity and by disorganization of protein globules. Treatment of animals with antioxidant insufficiency with ionol led to certain normalization of changes of physico-chemical characteristics of the learned membrane structures caused by lipid peroxidation.

Animals↗

PubMed1990

Some aspects of lead(II) DNA interactions.

The interaction of Pb(II) ions with calf-thymus DNA was studied by differential pulse polarography, sweep voltammetry, cyclic voltammetry, chromatography on hydroxyapatite and viscosity measurements. Pb(II) ions may interact with nucleic acid via phosphate groups causing some stabilization of the DNA structure. However, the more specific interaction occurs with nucleic bases. The latter interaction destabilizes the nucleic acid structure and leads to inter- and intra-chain binding.

Animals↗

PubMed1991

Transfer mechanism of quinine drug across the oil/water (O/W) interface.

The transfer phenomena of quinine drug at the aqueous 1,2-dichloroethane (DCE) interface have been studied by the current-scanning polarography. The relationships between the wave height and pH of aqueous phase, concentration of quinine as well as the rate of water drop are discussed. The effect of supporting electrolyte, buffer solution and the nature of organic solvent on the polarographic wave is studied. The transfer characteristics of quinine in aqueous phase and in organic phase are compared. The mono-protonated and diprotonated quinines can both transfer at the interface so as to produce two polarographic waves. The transfer process of quinine at the interface is simultaneously controlled by diffusion and reestablishment of the disturbed protonated equilibrium of quinine. A further investigation is made by chronopotentiometry. On the basis of the theoretical analysis, the formulae of the limiting current are derived and discussed. The theoretical results are in agreement with the experimental ones. The transfer mechanism of quinine is put forward.

Mathematics↗

PubMedDate not supplied

[Local capillarotrophic insufficiency syndrome in patients with osteoarthrosis deformans (polarographic and thermographic data)].

The condition of microcirculation in the region of the joints was studied by means of polarography on oxygen with an oxygen load and thermography on the Soviet high resolution television set "Paduga" in 30 patients with primary deforming osteoarthrosis (PDOA) and 15 practically healthy persons. Different direction shifts in the levels of supply and consumption of oxygen in the periarticular tissues in patients with PDOA were determined, a considerable drop in oxygen supply to the regions of the affected joints being noted. It has been established that thermography is a method of choice for diagnosis of secondary synovitis and other inflammatory affections of the joints.

Adult↗

PubMed1990

[Electroanalytical chemistry study of pilocarpine].

The electrochemical behaviour of pilocarpine was investigated by differential pulse polarography and cyclic voltammetry. The optimum conditions for the determination of pilocarpine were as follows: The electrolyte was 0.4 mol/L HAc-NaAc(pH 4.0) buffer solution, Zn (II) 1.0 x 10(-3) mol/L; initial potential -0.80 V (vs Ag-AgCl), final potential -1.30 V (vs Ag-AgCl), and voltage sweep rate 5 mV/s. A fair reproducibility in the above procedure and a good relationship between peak current and pilocarpine concentration (4.0 x 10(-6)-4.0 x 10(-5) mol/L) were achieved. The detection limit was 8.0 x 10(-7) mol/L. This paper also reports that the application of cyclic voltammetry to study electrode process behavior has been established. The PVC membrane ion-selective electrode for pilocarpine also was studied. It is based on the use of tetraphenylborate pilocarpine ion pair complex as the active material. The PVC membrane electrode showed Nernstian response over the pilocarpine concentration range from 1.0 x 10(-2) to 3.0 x 10(-5) mol/L, with a slope of 36 mV/decade, the detection limit being 3.0 x 10(-6) mol/L. The electrode gave fast response and good reproducibility. This method provides a rapid and simple way to the determination of pilocarpine in pharmaceutical preparations.

Electrodes↗