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Results for “Conductometry”

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At least 19 recordsLinked to original sources

PubMed1977

[Conductometry in determining measurements of urine electrolyte concentration (author's transl)].

1. Na+ concentration, measured by the flame photometer, cryoscopic osmolality, and the specific electrolyte conductivity of urine show a close statistical correlation if only small amounts of a molecular disperse solution are dissolved in the urine. 2. Since conductance of a fluid is an expression of its ion concentration, better relationships exist between Na+ concentration and conductivity than between Na+ concentration and osmolality. 3. In the presence of large amounts of glucose in the urine, osmolality no longer represents the electrolyte content, and therefore no longer serves as a parameter of renal concentration power. On the other hand, the close correlation between conductance and Na+ concentration remains. 4. Conductometry supplements osmometry significantly by its selective capacity to determine electrolyte components in the urine. 5. Owing to the short time spent on the method and small errors in technique, it remains debatable whether conductometry is preferable to osmometry in normal cases for determining measurements in concentration in the urine.

Child↗

PubMedDate not supplied

[Use of methods of derivative conductometry and photometry for assessing the structure of a cellular suspension].

Experimental proofs for the possibility of studying the dynamical structure of rotatory moving erythrocyte suspension with the methods of derivative conductometry and photometry are presented. The amplitude of the recorded impulses was proportional to the cell concentration and the angle velocity, and strongly depended on the shape of the suspended cells.

Cell Movement↗

PubMedDate not supplied

The kinetics of hydroxyl-radical-induced strand breakage of hyaluronic acid. A pulse radiolysis study using conductometry and laser-light-scattering.

Hydroxyl radicals were generated radiolytically in N2O- and N2O/O2(4:1)-saturated aqueous solutions of hyaluronic acid. The hydroxyl radicals react rapidly with hyaluronic acid mainly by abstracting carbon-bound H atoms. As a consequence of subsequent free-radical reactions, chain breakage occurs the kinetics of which has been followed using the pulse radiolysis technique. In the absence of oxygen, strand breakage was followed by the change in conductivity induced by the release of cationic counterions condensed at the surface of hyaluronic acid which is a polyanion consisting of subunits of glucuronic acid alternating with N-acetyl-glucosamine. It appears that strand breakage is not due to one single first-order process, however, the contributions of the different components cannot be adequately resolved. At pH 7 the overall half-life is 1.4 ms, in both acid and basic solutions the rate of free-radical induced strand breakage is accelerated (at pH 4.8, t1/2 = 0.6 ms; at pH 10, t1/2 = 0.18 ms). In the absence of oxygen there is no effect of dose rate on the kinetics of strand breakage. In the presence of oxygen in addition to conductometric detection, strand breakage was also followed by changes in low-angle laser light-scattering. These two techniques are complementary in that in this system the conductometry requires high doses per pulse while the light-scattering technique is best operated in the low-dose range. In the presence of oxygen a pronounced dose-rate effect is observed, e.g. at pH 9.7 after a dose of 9.4 Gy the overall half-time is approx. 0.5 s, while after a dose of 6.6 Gy the half-time is approx. 0.23 s. Both the yield and the rate of strand breakage increase with increasing pH, e.g. at pH 7 G(strand breaks) = 0.7 x 10(-7) mol J-1 and at pH 10.4, 4.8 x 10(-7) mol J-7. The radiolytic yields of CO2, H2O2, organic hydroperoxides, O2.- and oxygen consumption have been determined in gamma-irradiated N2O/O2(4:1)-saturated solutions of both hyaluronic acid and beta-cyclodextrin.

Carbohydrate Sequence↗

PubMed1990

[Automatic blood group determination in the ABO- and Rh-system using conductometry].

A method was developed and tested on the basis of conductometry for determining blood group-specific agglutinates in the AB0 and Rh-system (D). By comparing the measured particle numbers before and after administration of specific antisera or test erythrocytes and objective evaluation can be made whether agglutination has occurred or not. The calculated degrees of agglutination were compared depending on the method, sex, and age of patients. The method can be automated.

ABO Blood-Group System↗

PubMed1989

[Diagnosis of mucoviscidosis by examination of sweat: value of conductometry].

Two methods for the determination of sodium in the sweat after stimulation by pilocarpine-iontophoresis were compared in 227 patients, among them 27 with a known cystic fibrosis. These two methods were 1. the standardized method by flame fotometry (State Pharmacopoeia of the German Democratic Republic) and 2. the determination of the sweat conductance by the new apparatus "CF-Conductognost". Both methods showed a good correlation. We recommend the conductometry for the decentralized screening because it saves time and gives results immediately. But in all patients with a questionable or pathologic value of conductance the sweat test should be repeated with the standardized method. This concerns only about 10 per cent of all patients.

Adolescent↗

PubMedDate not supplied