SIMULTANEOUS DETERMINATION OF Cu(Ⅱ),Zn(Ⅱ),Fe(Ⅱ),Mn(Ⅱ),Co(Ⅱ) AND Ni(Ⅱ) WITH A SINGLE SWEEP POLAROGRAPHY

A new method of simultaneous determining Cu(Ⅱ), Zn(Ⅱ), Fe(Ⅱ), Mn(Ⅱ), Co(Ⅱ)and Ni(Ⅱ) with a single sweep polarography was developed. The experiment condition was studied and the results shou that the optimum base solution is that the residue got from evaporating 25 mL mixed solution, 2.5 mL 1.0 mol/L ethylenediamine, 3.0 mL 1 .0 mol/L ammonia-ammonium chloride,5.0mL, 10 % sodium sulfite and 0.5 mL 0.5 % gelatin were mixed and diluted to 25 mL, with water.Under the condition of this base solution, the polarography wave shapes of the six cations are ideal and without overlap of the peaks. In this base solution, Cu(Ⅱ), Zn(Ⅱ), Fe(Ⅱ), Mn(Ⅱ). Co(Ⅱ) and Ni(Ⅱ)in synthetic samples were determined with relative errors 0.4-9.4 % and relative standard deviations 0.8%- 12.2%. Under this experiment condition, one fold of Pb(Ⅱ), Cr(Ⅵ) and Mo(Ⅵ ) do not interere with the determination for Cu(Ⅱ). This method has been used to the simultaneous determination of the amount of the six cations in the samples of soil and Beiqi Tea. The relative standard deviations were 0.1%-2.1 % and recoveries were 93.5%-99.0 %.

Catalytic Kinetic Determination of Micro Amounts of Oxalic Acid by Second-Order Derivative Oscillopolarography

It was found that micro amounts of oxalate showed a very strong catalytic effect on the slow reaction between K 2Cr 2O 7 and Orange Ⅳ in a diluted sulfuric acid medium in a water bath at 70 ℃ . Orange Ⅳ exhibited a sensitive second order derivative polarographic wave at -0 50 V( vs . SCE). This provides the basis for a sensitive and selective catalytic kinetic method for oxalate determination with second order derivative oscillopolarography. The effects of sulphuric acid, K 2Cr 2O 7, and orange Ⅳ concentrations, reaction temperature and reaction time were investigated. A calibration curve of oxalate in the range of 0 1-2 0 μg/mL was obtained by the fixed time procedure. The detection limit was 0 03 μg/ mL. The possible interference from co existing substances or ions was examined. The new method has a high sensitivity and a good selectivity compared to other existing methods for oxalic acid determination. It has been applied to the determination of micro amounts of oxalate in real urine samples with satisfactory results.

Determination of Consuming Rate for Pb－Ag－Ca Anode in Preparation of Electrolytic MnO＿2 by Differential Pulse Polarography

The determination of trace element Pb in electrolyte MnSO_4H_2SO_4 was studied with differential pulse po-larography. The trace Pb was originated from new type Pb-Ag-Ca alloy anode being used in preduction processof electrolytic MnO_2 (EMD). The KCl was added as background of electrolyte. The differential pulse polarco-gram obtained for Pb(Ⅱ) is well in peak contour and is easy to determination. The peak potential is -0. 44 V(vs Ag-AgCl potential , experimental valuel). The Pb content may be determined by standard addition methodwhich is simple , reliable and fast. This study presents some foundamental data for Pb-Ag-Ca anode (abbreviated to PAC anede). The consuming rate for PAC anode is evaluated as 4. 82% annually.

Determination of Naphthalene by Single Sweep Polarography

A second derivative polarographic wave of naphthalene is observed in 50% N, N-dimethylformamide and ammonia-ammonium chloride medium. The peak potential is about ?1.05 V (vs. SCE). The concentration of naphthalene is linear with peak current in the range of 5.00×10?6 mol/L to 5.00×10?4 mol/L, The detection limit is 2.00×10?6 mol/L. This method can be used to determine naphthalene content of the sample such as coal, mothball and asphaltic bitumen. The relative standard deviation (RSD) are in the range of 0.38%≈1.30%. The determined recoveries by adding known amounts of naphthalene to sample solution are in the range of 92%≈101%. This paper also study on the polarographic behavior of naphthalene.

Studies on Quantitative Determination of Active Principles in Chinese Herbal Medicine by Second Derivative Differential Pulse Polarography

The second derivative differential pulse polarography was developed for the quantitative determination of active principles in medicinal herbs (baicalin in Scutellaria baicalensis Georgi, indigo in Baphicacanthus cusia (Nees) Bremek, paeonol in Paeonia suffruticosa Andr and piperine in Piper longum L ) The C O group in baicalin, indigo, paeonol and piperine could be reduced to CH OH in acidic solution at the dropping mercury electrode, and showed very good second derivative differential pulse polarographic peak at 1 550V, 1 300V, 1 630V and 0 860V (vs Ag/AgCl) respectively The linear relationship between concentration of baicalin, indigo, paeonol, piperine and peak height was obtained in the concentration range of 4 5×10 5 ～ 2 7×10 4 mol·L 1 , 3 8×10 5 ～ 4 2×10 4 mol·L 1 , 1 0～6 0×10 4 mol·L 1 and 7 0×10 5 ～2 5×10 4 mol·L 1 and the determination limits were 9 0×10 8 mol·L 1 , 8 4×10 9 mol·L 1 , 9 2×10 9 mol·L 1 and 8 7×10 9 mol·L 1 respectively This method is simple, rapid and sensitive, and the results are accurate

Determination of Vitamin B12 Using Differential Pulse Polarography

Vitamin B12 is a type of vitamin also known by the name cobalamin. B12 is involved in many metabolism activities, including DNA synthesis, nervous system, red blood formation and immune system. Therefore, we chose the Differential Pulse Polarography (DPP) method is that has a high sensitivity for the determination of vitamin B12. This determination was possible with cobalt present in vitamin B12 structure. Since Co(III) is formed from the oxidation of the vitamin, its polarographic behavior had to be determined in various electrolytes such as acetate, borate, phosphate and ammonia. The polarograms of Co(III) were taken in these electrolytes in which 1.0 M NH3/ (pH = 9.8) and 1.0 M AcOH/AcO- (pH = 4.0) were found as the most suitable electrolytes. This method was successfully applied vitamin of B12 determination in a 1 mL ampoule with high precision. The LOD was found as 3.7 × 10-7 for instead of (S/N = 3). Besides Co(III), interference effects of Zn(II), Ni(II), Cr(III), Fe(III), Cu(II), Cd(II) and Se(IV) were also studied. It was found that only Zn(II) peak had an overlap Co(III) peak in ammonium buffer. This problem could be solved by working in 1.0 M AcOH/AcO- (pH = 4.0) buffer. B12, which is 1000 μg in 1 mL vitamin ampoule, was found for 4 measurements as 999 ± 15 μg as a result of 95% confidence interval.

Study on the determination of trace rhenium(Ⅶ)by the adsorption differential pulse polarography

The determination of trace rhenium(Ⅶ)by differential pulse polarography in the system of H_2SO_4-(NH_2OH)_2·H_2SO_4-TeO_4^(2-) is markedly improved by the addition of Nitron,which is adsorbed on the surface of mercury electrode.The limit of detection is down to 2×10^(-10) M.The adsorptive peak potential is -0.80V(vs.SCE).In the ranges of 5×10^(-10)-10^(-8),1×10^(-8)-10^(-7) and 1× 10^(-7)-10^(-6)M,there are good linear relationships between the peak current increment and the concentration,of which the relative standard deviations are 9.5,6.6,1.8% respectively with the correlation coefficients of linear regression of 0.995—0.999.The results relating to this polarographic wave show that it is an adsorption-catalytic wave.The mechanism of the electrode reaction is dis- cussed.

Determination of Stability Constants of Cadmium-Glycine Complexes by a Unified Treatment for Potentiometric and Polarographic Data

The cadmium（Ⅱ）-glycine system was studied by the two experimental techniques, ion sensitive electrode （ISE） and differential pulse polarography （DPP）, and the experimental data obtained were used by a unified mathematical treatment to calculate the complex stability constants. The combination of the two techniques is of many advantages as ISE can be performed at low [LT]：[MT] ratios and significantly higher [MT], whereas DPP could be used well at large [LT]：[MT] ratios and much smaller [MT]. This makes it possible to study a metal-ligand system in a relatively broader range of experimental conditions that, in turn, provides more information about the metakligand system of interest. Applying the unified mathematical treatment to the cadmium-glycine system, two new complexes MHL and ML2（OH） as well as three complexes ML, ML2 and ML3, reported in literatures, could be modeled and all their stability constants have been refined.

Polarographic Studies on Associations of Midecamycin and Chloroquine with Hydrogen Peroxide

The associations of each of midecamycin and chloroquine phosphate to hydrogen peroxide were studied by using linear-potential scan polarography. In a 0.15 mol/L KH 2PO 4-NaOH(pH 7.4) buffer, the association ratio of the association complex of midecamycin to hydrogen peroxide is 1∶1, and the apparent association constant is 7.18. While in a 0.04 mol/L NH 3·H 2O-NH 4Cl(pH 9.5) buffer, the association ratio and the apparent association constant of the association complex of chloroquine phosphate to hydrogen peroxide are 1∶1 and 45.4, respectively. The formation of the association complexes stabilizes H 2O 2 and results in the accumulation of H 2O 2, which is baneful to human body.

Preparation of a New Solid-State Molybdenum-Selective Electrode and Application

A new solid state molybdenum-selective electrode has been developed. The electrode is composed of 20% MoS2, 60% Ag2S, and 20% Cu2S. An analytically useful potential change occurred, from 1 × 10-5 to 1 × 10-1 M molybdenum ion. The slope of the linear portion (1 × 10-1 - 1 × 10-5 M) was about 45 ± 2 mV/10-fold concentration changes in molybdenum. It was found that pH change between 1 and 12 had no effect on the potential of the electrode. There was no interference of most common cations such as K+, Na+, Ca2+, Mg2+, Cu2+ and Fe3+ anions such as Cl-, ,? and . The lifetime of the electrode was more than 2 years, when used at least 4 - 5 times a day, and the response time was about 30 s. This electrode has been used for the determination of molybdenum ion in wine using standard addition method. The validation of the electrode has been made with a commercial molybdenum DP polarography and high consistency was obtained.

巯基棉分离富集催化示波极谱法测定精锡中微量砷

本试验研究了催化极谱法测定精锡中微量砷的方法。在6mol/L盐酸酸度下,用巯基棉将砷(Ⅲ)定量吸附,使其与基体锡及共存元素Sb、Cu、Pb、Fe、Bi、Zn、Al等分离。吸附砷(Ⅲ)后的巯基棉用H_2SO_4-H_2O_2消解,在3.38mol/L H_2SO_4-0.12mol/L KI-3.13×10^(-5)mol/L Te底液中测定砷催化极谱波,As量在0.04～O.4μg/mL之间线性良好。回收率平均为98.9%,用两个精锡试料进行11次测定,平均值分别为1.51×10^(-3)%和4.61×10^(-4)%,RSD为5.2%及8.4%。

4-(2-QUINOLYLAZO)-1, 3-DIHYDROXY-NAPHTHALENE——A NEW SENSITIVE ANALYTICAL REAGENT FOR TRACE COPPER DETERMINATION

The azo compound 4-(2-quinolylazo)-1,3-dihydroxynaphthalene (2-QADNm) has been synthesized and used as a new sensitive spectrophotometric and electroanalytical reagent for determination of trace amounts of copper. In dilute alkaline solutions, 2-QADNm shows a single-sweep polarographic wave at -0.95 V (vs. SCE). In the presence of copper(Ⅱ) two new waves appear at -0.52 and -0.79 V. Using the wave at-0.79 V, a trace amount of copper down to 10^(-8) mol/L can be determined. The electroanalytical characteristics of 2-QADNm and the electrochemical reaction mechanism of the copper(Ⅱ)-2-QADNm complex have been studied in detail by the use of various electrochemical techniques. In alkaline solutions, 2-QADNm forms red complex with copper(Ⅱ) which has an absorption peak at 526 nm, the molar absorptivity being 6.4×10~4 1·mol^(-1)·cm^(-1). In the presence of a non-ionic surfactant the molar absorptivity of this complex is 1.6×10~5 1·mol^(-1)·cm^(-1).

STUDY ON THE ADSORPTIVE COMPLEX WAVE OF RARE EARTH IONS WITH MORIN

Ⅰ. INTRODUCTIONBy using extraction-spectrophotometry or extraction-fluorophotometry, some methods were utilized to study the complexes of rare earth ions with morin (MOR). The authors propose that the rare earth ions form unstable complexes with morin only in weak acidic so-

Polarographic immunoassay coupled with catalytic amplification of labeled copper ions

A new approach of polarographlc immunoassay based on the catalytic amplification of the labeled metal ions and the polarographlc detection of the catalytic product was developed.In this approach,the copper ions used as the catalyst for substrate conversion instead of natural enzyme were labeled to model antigen diphtheria toxoid (DT) through the bifunctional chelating reagent diethylenetriamine pentaacetic acid (DTPA).After heterogeneous competitive imrnunoreaction,the oxidation of substrate o-phenylenediatnine (OPD) was catalyzed by the labeled copper ions to generate an electroactive product 2,3-diammophenazine (DAP); subsequently,the product DAP was detected with linear-sweep polarography The proposed assay can determine the concentration in the range of 10-1 000 ng/mL of DT,two orders of magnitude more sensitive than those based on the direct detection of the metal ion labels The proposed immunoassay can be applied to detecting various proteins of interest.

Polarographic immunoassay coupled with catalysis of non-radioactive multiple iodine label

A now polarographic immunoassay was developed In this assay,human serum albumin (HSA) as the model antigen was covalently labeled with organic compound erythrosin B(EB) containing four non-radioactive iodides through Ⅰ step chemical reaction The labeling procedure is simple and the conditions needed are moderate.The molar labeling ratio of KB HSA was 12 Ⅰ The content of iodine in the conjugate obtained by the proposed procedure is ninth higher than that by the other existing methods.A heterogeneous competitive immunoassay was established by compling the catalysis of the conjugate to substrate As(Ⅲ)-Ce(Ⅳ) reaction with the linear-sweep polarographic detec-tion of As(Ⅲ) amount HSA can be determined in the HSA concentration range from 1 to 200μg/mL,with the de-tection hum of 0 66μg/ml.

Investigation on property and mechanism of redox wave of methylhesperidine at Hg electrode

The voltammetric behaviors of methylhesperidine (MH) were studied by means of linear sweep voltammetry, cyclic voltammetry and normal pulse voltammetry. In the Brit ton-Robinson buffer solutions with pH values from 2.05 to 6.37, MH could yield three reduction waves PC1, PC2 and PC3. PC1 wave is an adsorptive pre-wave. PC2 wave is an irreversible reduc tion of pre-protonated MH involving one electron and one proton. PC3 wave is an irreversible wave of reduction species radical of MH involving one electron.

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 be-tween the wave height and pH of aqueous phase, concentration of quinine as well as therate of water drop are discussed. The effect of supporting electrolyte, buffer solution andthe nature of organic solvent on the polarographic wave is studied. The transfer char-acteristics of quinine in aqueous phase and in organic phase are compared, The mono- pro-tonated and diprotonated quinines can both transfer at the interface so as to produce twopolarographic waves. The transfer process of quinine at the interface is simultaneouslycontrolled by diffusion and reestablishment of the disturbed protonated equilibrium ofquinine. A further investigation is made by chronopotentiometry. On the basis of thetheoretical analysis, the formulae of the limiting current are derived and discussed. Thetheoretical results are in agreement with the experimental ones. The transfer mechanismof quinine is put forward.