共查询到20条相似文献,搜索用时 15 毫秒
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A systematic study of various experimental parameters which may influence the response time and precision of an automated polarographic system is described. The effects of segmented streams, flow rate, pump stop during sample shifts, debubbler position, current damping, scale expansion, sampling rate and type of deaerating gas are discussed. Low response times are favoured by the use of segmented streams, a high aspiration rate, a short distance between the debubbler and the working electrode and a low current damping, while the best precision is obtained by using scale expansion, pump stop during sample shifts, a low sampling rate and argon gas for deaeration. Under optimized conditions a standard deviation of 0.3 % was obtained. 相似文献
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A constat-potential pulse waveform is applicable for the polacographic analysis of buffered solutions (pH ?= 7) of cathodically active metal ions without voltammetric interference from dissolved oxygen. The technique is demonstrated at a dropping mercury electrode for detection of lead(II) and cadmium(II) in a conventional polarographic Cell (ca. 75 ml) as well as for small samples (2 ml) in a flow-injection system. The flow-injection polarographic technique is recommended for higher sample throughout than conventional polagraphy and is demonstrated for an electroless copper plating solution containing about 1.5 × 10–2 M copper(II). 相似文献
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Differential pulse polarography is assessed as amethod for the determination od N-nitrosodiethanolamine (NDEA) in aqueous media. Optimum conditions with respect to pH and supporting electrolyte are found with simple mineral acid solutions (H2SO4) at pH 1–2. Detection limits in this medium are of the order 5 × 10-5 M NDEA. the procedure is applied to the direct determination of NDEA in commercially available grinding fluids which contain, on manufacture, precursors for nitrosamine formation. High concentrations of NDEA were found (75 μM) with an estimated accuracy better than 92% and a precision of ±8%. 相似文献
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Electrothermomechanical film (ETMF) is a cellular, biaxially oriented plastic film which is coated with electrically conductive layers. It is an elastic impedance. ETMF relates electrical, mechanical, and thermal energies as well as parameters. The functional basis of the film comprises the compression of gases, the mechanical parameters of the film, and the electric or magnetic field. By exploiting these basic characteristics, the film can be used in measuring techniques, in acoustics, in ultrasonics, in motion elements, in energy transformation, etc. 相似文献
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A novel design of the cross-axis synchronous flow-through coil planet centrifuge is introduced. The apparatus holds a pair of large coil holders symmetrically, one on each side of the rotary frame, at a lateral position 12.5 cm from the center of the holder shaft held 10 cm from the centrifuge axis. Mathematical analysis of acceleration generated by the planetary motion of the apparatus revealed a unique centrifugal force field which promises high retention of the stationary phase in the multilayer coil to perform efficient preparative-scale counter-current chromatography. 相似文献
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The theory of transient processes in photogalvanic cells is developed. The systems treated consist of a photoactive species B which can be oxidized (or reduced) to A in its excited state B* by a one-electron acceptor Z which itzelf is reduced (oxidized) to Y. It is further assumed that both redox couples undergo one-electron transfer reactions at the metal electrodes. The electrode kinetics for both redox couples is taken into account. A computer program is described with which the following data can all be obtained as functions of time, after illumination has started: current, potential of the illuminated electrode, potential of the dark electrode, power, and the concentration profiles of A, B, Z and Y near the electrodes. 相似文献
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An HPLC method with polarographic detection for the trace determination of artemether in plasma and whole blood was developed and applied to pharmacokinetic and clinical pharmacological studies. The method showed high sensitivity and selectivity because of the easy reduction of the peroxide linkage of artemether at the mercury drop electrode. The detection limit was 10 ng and the detector response was linear over the range of 10 ng to 1 microgram artemether injected onto the column. The largest relative standard deviation of 10 replicate measurements of standard solutions (concentrations of 10 ng/mL-1 microgram/mL) was 8%. The recovery from whole blood and plasma of added drug (concentrations of 15-480 ng/mL) was 71-100%. 相似文献
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A systematic scheme of separation by solvent extraction methods is described for 19 metals. 相似文献
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The influence of triethylenetetraminehexaacetic acid (TTHA) on the d.c. and square-wave polarographic curves of Cu(II), Pb(II), Cd(II), Ni(II), Co(II), Zn(II), Fe(III), Bi(III), Sb(III), As(III) and In(III) has been investigated in several supporting electrolytes over the pH range 1–13. The E and Ep values with and without a 10-fold excess of TTHA are compared. Some analytical applications are suggested. 相似文献
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Alejandra Salerno Monica E. Hedrera Isabel A. Perillo Norma B. D'Accorso Miriam Martins Alho 《Journal of heterocyclic chemistry》2000,37(1):57-62
The electron impact mass spectral fragmentation pathways for a series of 1,3‐di‐ and 1,2,3‐trisubstituted imidazolidines were investigated. The data show remarkable differences depending on the location and identity of substituents. The atypical 1,2,2,3‐tetrasubstituted imidazolidine, 2‐cyano‐1‐methyl‐3‐(p‐nitro‐phenyl)‐2‐phenylimidazolidine, was also investigated. 相似文献
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Anodic stripping voltammetry at a glassy carbon disc electrode covered by a thin mercury film was adapted for use in a flow-through cell. The resulting system is characterized by extreme simplicity of set-up and operation, high sensitivity and excellent precision and stability. Its performance was tested via the determination of hydrated or labile complex ions of heavy metal ions in sea water, using short (2–10 min) deposition periods. The dependence of the stripping peak charge on metal ion concentration, length of deposition period, solution flow rate and other variables was examined and the reliability of the results obtained were evaluated under conditions resembling continuous monitoring. 相似文献
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Francesco Pergola Maria R. Moncelli Rolando Guidelli 《Journal of Electroanalytical Chemistry》1980,107(2):295-306
A polarographic investigation of CuII electroreduction from solutions of benzotriazole (BTA) of pH from 1 to 3 at a dropping mercury electrode shows the presence of two successive adsorption waves of equal height (waves Ic and IIIc) due, respectively, to the formation and to the subsequent dissolution of an adsorbed film of a CuI compound. The dependence of the half-wave potential of wave IIIc, which is polarographically reversible, upon pH and BTA concentration indicates that the adsorbed film has the composition [CuI(BTA?)], where BTA? denotes the deprotonated anionic form of benzotriazole. Moreover, the maximum height of wave IIIc indicates that this film is one monolayer thick. A third cathodic wave (wave IIc), lying between waves Ic and IIIc, stems from the reduction to the metal state of the CuII ions diffusing from the bulk solution. Copper(0) oxidation at dropping amalgam electrodes in BTA solutions yields two successive adsorption waves (waves Ia and IIa). Wave Ia is due to the same electrode process, Cu0 (Hg)+BTA?CuI(BTA?)+H++e, responsible for the cathodic wave IIIc. On the other hand, wave IIa is due to the formation of roughly two adsorbed monolayers of [CuI(BTA?)] upon that formed along wave Ia. 相似文献
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Differential pulse polarographic methods are reported for the determination of N-nitrosodiphenylamine and N-nitrosodibutylamine in aqueous media. Optimum conditions for analysis were obtained with acetate buffer (pH 3.74) and 0.01 M H2SO4, where reduction peak separations were of the order of 300 mV and 200 mV, respectively. Detection limits were approximately 3×10-8 M for each compound. Methods for the extraction of these nitrosamines from iso-octane to aqueous solutions were quantitatively examined. 相似文献
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Luigi Mondello Keith D. Bartle Giovanni Dugo Paola Dugo 《Journal of separation science》1994,17(5):312-314
The application of a new method, computer-controlled on-line HPLC-HRGC, to the analysis of the components of sweet orange oil has enabled the determination of aldehydes without interferences. HPLC was used to separate the oil aldehydes into three fractions, aliphatic aldehydes, sesquiterpene aldehydes, and monoterpene aldehydes. These fractions were transferred automatically to the GC, where the individual aldehydes were separated into well resolved chromatographic peaks. 相似文献
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