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PubMedDate not supplied

Improved polarographic method for determination of glyphosate herbicide in crops, soil, and water.

A prior method for determination of glyphosate in water samples has been modified to accommodate samples of crops and soils. Differential pulse polarography as the determinative step enables analysis in an aqueous medium, which is important during extraction of this compound. Residues are cleaned up and concentrated by ion exchange on a strong basic resin in OH- form. The method is rapid, is applicable to a relatively broad selection of sample types, and gives recoveries consistently better than 60% with good precision. The main shortcoming of the method is that the limit of detection of 0.5-1.0 ppm may sometimes be inadequate. The metabolite, aminomethyl phosphonic acid, is not detected.

Chemical Phenomena↗

PubMedDate not supplied

DC polarographic assay of piperazines.

Piperazine, piperazine salts, and piperazine-containing compounds, e.g., diethylcarbamazine and piperazine theophylline, are determined by direct current polarography of the corresponding nitroso-derivative. The nitroso-derivative exhibits a well defined cathodic wave at -0.8 V vs SCE. The plot of peak height vs concentration is rectilinear between 1.6 X 10(-5) and 19.2 X 10(-5) M. Recoveries from bulk drugs were 97.7-101.12% with a standard deviation of 2.14-3.44. The procedure was successfully applied to analysis of drug content in representative dosage forms with good accuracy.

Buffers↗

PubMed1979

[Liver function disorders and hepatic insufficiency in diseases of the abdominal cavity organs].

The tissue respiration and oxidative phosphorylation in mitochondrial preparations of the liver were studied by means of the polarography in 14 cases of peptic ulcer localised in the stomach and the duodenum and 46 cases of cancer of the stomach. The deterioration of the indices of oxidative phosphorylation in the liver (decrease of the respiratory control, desintegration of the respiration and phosphorylation processes) has been found to occur with the development of the tumor process.

Adult↗

PubMed1979

[Local pO2 measurements in the cochlear perilymph of guinea pigs in oxygen and oxygen/carbon dioxide breathing (author's transl)].

After breathing a mix of 10% CO2 and 90% O2 or hyperbaric O2 (2 bar absolute) an appreciable rise of pO2 can be demonstrated by D.C. polarography in the scala tympani of the guinea pig chochlea. When test animals are made to breathe 100% pure O2 at normal pressure the rise of pO2 is significantly less pronounced. The observations made in these animal experiments suggest that the inhalation of CO2O2 currently constitutes the only valid inhalation treatment in acute inner ear deafness. Further compression of hyperbaric O2 is associated with a clear-cut rise of pO2. It should, however, be remembered that hyperbaric oxygen may produce toxic effects in various body tissues.

Animals↗

PubMed1979

Electrochemical properties of polycyclic compounds studied by the polarographic method in anhydrous systems. VII. Polarographic oxidation of carcinogenic hydrocarbons in dimethylformamide.

The electrooxidation of polycyclic carcinogenic hydrocarbons in dimethylformamide solutions was studied by polarography. The results generally have confirmed that a correlation exists between oxidation potentials and carcinogenic activity of the studied polycyclic aromatic hydrocarbons. The half-wave potentials of the polarographic curves have been found to be directly related to the root xn of the Hückel secular equation for the highest bonding orbital and to the reduction potentials measured in dimethylformamide.

Carcinogens↗

PubMed1982

Moxalactam disodium compatibility with intramuscular and intravenous diluents.

The stability of moxalactam disodium with mannitol injection in combination with intramuscular and intravenous diluents was investigated. Solutions were stored in original glass containers stoppered with butyl rubber closures or in polyvinyl chloride bags. Five diluents were evaluated at an intramuscular concentration of moxalactam 1 g (as the disodium salt) in 3 ml of diluent. Twenty intravenous diluents were evaluated with moxalactam 1 g (as the disodium salt) in 50 or 500 ml of diluent. High-performance liquid chromatography, polarography, thin-layer chromatography, spectrophotometric color evaluations, nephelometry, and pH determinations were performed. Solutions were assayed initially after reconstitution and stored for subsequent assay at refrigerator (5 degrees C) and room (25 degrees C) temperatures. The moxalactam disodium solutions were stable for up to 96 hours when stored at 5 degrees C or 24 hours when stored at 25 degrees C. The color, clarity, and TLC data were satisfactory for all diluent combinations tested. Polarographic, HPLC, and TLC data showed that the degradation products remained within acceptable limits when stored for 96 hours at 5 degrees C or 24 hours at 25 degrees C. The slight pH changes were within regulatory limits for moxalactam. The moxalactam disodium solutions maintained at least 90% of initial potency for up to 96 hours when stored in a refrigerator. If kept at room temperature, the reconstituted solutions should be used within 24 hours.

Cephalosporins↗

PubMedDate not supplied

Rapid differential pulse polarographic determination of tiaprofenic acid.

Tiaprofenic acid (Surgam) has been determined directly by using differential pulse polarography (DPP) and pH 5.5 acetate buffer as a supporting electrolyte. The differential pulse polarogram was obtained under constant amplitude pulses of 50 mV superimposed on a linearly increasing dc ramp. Peak current was measured at the peak potential of -0.990 V vs Ag/AgCl reference electrode. Under the experimental conditions used, a linear relationship between peak current and concentration was established over the range 0.5-5.0 micrograms/mL. Mean percentage recoveries for tiaprofenic acid in authentic and tablet forms were 100.27 +/- 2.25 and 99.45 +/- 1.44, respectively. The results obtained by the DPP method were compared with those of the spectrophotometric method used by the manufacturer for the analysis of tiaprofenic acid and its tablet form.

Hydrogen-Ion Concentration↗

PubMedDate not supplied

[Determination of copper, lead and zinc in fruit preserves].

Copper, lead and zinc content in canned fruit manufactured in Moldavia in 1979 and 1980 was determined by polarography and atomic-absorption spectrophotometry. The authors developed a method for determining the above trace elements in one sample using an atomic-absorption spectrophotometer. The errors of each method were calculated. It was ascertained that the data obtained by both the methods were identical. Analysis of the data indicates that the content of copper, lead and zinc is within the standards approved by the USSR Ministry of Health. The data obtained in the studies can be used in both toxicological work on setting standards of heavy metals content in canned food and in the tables of the chemical composition of canned food. The methods for copper, lead and zinc determination can be used as the basis for the development of standard procedures for heavy metals.

Copper↗

PubMed1984

Osmium-induced alteration in DNA structure.

In the presence of pyridine and other ligands osmium tetroxide binds covalently to pyrimidine bases in DNA. Properties of osmium-modified native and denatured calf thymus DNA, and plasmid Co1E1 DNA were investigated by means of differential pulse polarography, absorption spectrophotometry, circular dichroism, agarose gel electrophoresis, and nuclease S1 digestion. A great difference in the reaction kinetics of native and denatured DNAs with osmium, pyridine was observed. On the ground of the slow stepwise reaction kinetics of native DNA in the initial stage of its modification by osmium it has been suggested that the primary reaction sites do not include bases contained in the intact double helix. Osmium binding to sporadic primary reaction sites (represented e.g. by bases in the vicinity of a single-strand break) in native calf thymus DNA resulted in local changes in DNA conformation limited to a close neighbourhood of the binding site. At higher osmium/nucleotide ratios disordering of the DNA structure over a region extending beyond the immediate binding site was observed. With denatured DNA the same type of structure disordering was detected already in the initial stage of the reaction at osmium/nucleotide ratios as low as 0.01. Osmium binding to the supercoiled Co1E1 DNA resulted in its relaxation without nicking and it increased its sensitivity to linearization by cleavage with nuclease S1. The behaviour of Co1E1 DNA has been explained by the formation of a denatured region in the molecule (accompanied by a coupled loss of duplex and superhelical turns). It has been suggested that osmium can be used to label and to visualize distorted regions in the DNA double helix.

Animals↗

PubMed1983

Polarographically detected effect of ultrasound and irradiation on DNA solution.

Aqueous solutions of DNA were sonicated, irradiated, or sonicated and irradiated. The effect of the treatment was detected by pulse-polarography. The polarographic response of irradiation depended on the concentration of DNA. It was found that the effects of sonication and irradiation were non-additive. The reason for this is discussed briefly.

Animals↗

PubMed1983

Electrochemistry of double-stranded complexes of synthetic polyribonucleotides having interferonogenic and antiviral activity.

Double-stranded (ds) complexes of poly(C) with poly(G) and poly(G,I) were studied using differential pulse polarography (DPP) and differential pulse voltammetry at a pyrolytic graphite electrode (DPV). The complex formed by copolymer was found to be DPP inactive. On the other hand, poly(G).poly(C) yielded a small DPP peak corresponding to single-stranded (ss) poly(C). It was suggested that ss poly(C) present in the solutions of poly(G).poly(C) appeared due to the existence of segments in poly(G) during the complex-forming process in which guanine residues were unable to be hydrogen-bonded with bases in poly(C). Polynucleotide complexes investigated in this report yielded a DPV peak corresponding to electrooxidation of guanine residues, which was markedly lower than that yielded by ss polymers. Moreover, this DPV peak yielded by the complex prepared from an equimolar mixture of poly(G) and poly(C) was still markedly higher than that yielded by poly(G,I).poly(C), or by poly(G).poly(C) prepared in the excess of poly(C). The lowering of the DPV peak was explained as being particularly due to the presence of the polynucleotide segments with an intact and regular secondary structure. The results of our electrochemical analysis of the complexes investigated were compared with their biological activity reported earlier. This comparison calls attention to the fact that biological effectiveness of these biopolymers may be dependent on details of their secondary structure which may be monitored using the methods of electrochemical analysis.

Antiviral Agents↗

PubMedDate not supplied

[Polarographic method of studying natural cobalamins in mixtures].

By means of polarography and tree-angle scan voltammetry, AdoCbl, MeCbl and OH-Cbl were studied in mixtures and separately. The possibility to obtain a polarographic scope of quality for each of the natural cobalamins studied was shown. The ability of cobalamins to be adsorbed on a mercury electrode enables to increase the sensitivity of the method by conducting the accumulative adsorption from solutions with the concentration up to 1 microgram/ml.

Adsorption↗

PubMed1980

[Selective electrochemical method of quantitative determination of chlorides in biological material].

An experiment was made to test the possibility of the quantitative analysis of chlorides in biological material by the modern potentiometric method using an ion-selective electrode. The results were compared with the current practical methods--polarography and photometry. The results demonstrate the suitability and benefits of the use of the ion-selective electrode, mainly in the series determination of Cl- ion concentration in biological material. The expediency of the tested analytical method and its well-reproducible results demonstrate the advantages of the ion-selective method in the analysis of chlorides in biological material, as compared with the polarographic and photometric methods.

Animals↗

PubMed1982

Oxygen dissociation curves for whole blood, recorded with an instrument that continuously measures pO2 and sO2 independently at constant t, pCO2, and pH.

We describe a method for recording oxygen dissociation curves for whole-blood specimens. The blood sample is placed in a thermostated measuring chamber, and pO2 and SO2 are measured continuously by polarography and by reflectometry, respectively. During the recording of an oxygen dissociation curve, the pO2 and SO2 signals are stored in a data-acquisition system, while pH, pCO2, and temperature are kept constant. Determination of precision and error discussion indicated that the coefficient of variation (CV) of the determination of the oxygen dissociation curve is mainly determined by the error in the measurement of SO2. The overall CV of pO2 values belonging to the lower, mid-, and upper parts of the SO2 range is estimated to be about 2.6, 3.1, and 2.1%, respectively. In practice the measurements are about 30% more precise than estimated. With our method, the fixed-acid-induced Bohr effect (H+ factor) can be determined over the entire SO2 range with much greater precision than hitherto.

Blood Gas Analysis↗

PubMed1983

Determination of copper, nickel, and chromium in foods.

A collaboratively studied method for Pb, Cd, As, Se, and Zn that uses a closed system digestion technique has now been extended to include 3 additional elements, Cu, Ni, and Cr. Cu is determined by either atomic absorption spectrophotometry or anodic stripping voltammetry, depending on the concentration. Ni and Cr are determined by differential pulse polarography. Analysis of National Bureau of Standards reference materials by this procedure gives values in close agreement with the accepted values. Recoveries from applesauce and chicken spiked at 0.6-4 micrograms/g are in the 92-101% range. The sensitivity of the multielement procedure is 0.34, 0.14, and 0.24 microgram/g for Cu, Ni, Cr, respectively, at the 90% confidence level.

Chromium↗

PubMed1982

Differential pulse polarographic determination of total iodine in milk.

A differential pulse polarographic method for total iodine in milk is presented. Samples are ashed, sodium hypochlorite is added to oxidize iodide to iodate, and the product is mixed with sodium sulfite solution and measured by differential pulse polarography at -90 V against SCE. The standard deviation for 53 duplicate samples was 0.011. Average recovery for 10 or more samples at different levels was 98.6% with a standard deviation of 2.9%.

Animals↗

PubMed1982

[Reduction of dehydroascorbic acid by thiols in presence of biocatalytic substances: polarographic study].

The chemical reduction of dehydroascorbic acid is studied in the presence of organic and vitaminic compounds. Redox properties of the compounds: ascorbic acid, dehydroascorbic acid, thiols such as glutathion, cistein, British anti-Lewisite (BAL), thiamin, riboflavin, para amino benzoic acid, biotin, 1-4 dihydronaphtoquinone and flavonoids (flavone and derived salts, quercetin rutin, 1-epicatechin and dimer) are established by direct and pulse polarography. The redox reactions are analysed by amperometry. From the results, it appears that the catalytic effect of biocatalyst of the dehydroascorbic reduction by thiols has no direct relation with the redox properties. This catalytic effect is specifically obtained with flavan-3 ol complex with antiscorbutic activities of C2 factor type.

Ascorbic Acid↗

PubMed1982

AC polarographic determination of cloxacillin.

Hydrolysis of cloxacillin at pH 4.0 yields an electroactive product which can be determined by polarography. Depending on the concentration of cloxacillin, one of 2 peaks was obtained: The potential ac peaks for a 4.36 mM cloxacillin solution were peak I, -0.23 V and peak II, -0.13 V. For analytical purposes, the first peak was used. A linear relationship was established for levels of cloxacillin between 2.2 X 10(-5) and 2.2 X 10(-3)M. Average recovery was 98.8% (SD 1.8), indicating satisfactory accuracy for the method. Individual capsule and composite assays as well as interference tests are described.

Capsules↗