Mercury selective electrochemical sensor based on a double armed crown ether as ionophore

PVC based membranes of a double armed crown ether, N, N'-dibenzyl, 1,4,10,13-tetraoxa-7, 16-diaza cyclooctadecane (I) as ionophore with sodium tetra phenyl borate (NaTPB) as anion excluder and with many plasticizing solvent mediators have been prepared and used for Hg(II) ion determination. The membrane with DBBP (dibutyl butyl phosphonate ) as plasticizer with various ingredients in the ratio PVC: I: NaTPB: DBBP (150: 12: 2: 100) shows the best results in terms of working concentration range (3.1x10-5-1.0x10-tM) with a Nernstian slope (29.0′0.5 mV/decade of activity). The electrode works in the pH range 2.1-4.5. The response time of the sensor is 15s and it can be used for about 4 months in aqueous as well as in non-aqueous medium. It has good stability and reproducibility. The potentiometric selectivity coefficient values for mono-, di-, and trivalent cations are tabulated. The sensor is highly selective for Hg2+ in the presence of normal interferents like cadmium, silver, sodium and iron.

Sorption of metals on humic acid

The sorption on humic acid (HA) of metals from an aqueous solution containing Hg(II). Fe(III), Pb, Cu, Al, Ni, Cr(III), Cd, Zn, Co and Mn, was investigated with special emphasis on effects of pH, metal concentration and HA concentration. The sorption efficiency tended to increase with rise in pH, decrease in metal concentration and increase in HA concentration of the equilibrating solution. At pH 2.4. the order of sorption was: Hg Fe Pb Cu=Al Ni Cr=Zn=Cd=Co=Mn. At pH 3.7. the order was: Hg and Fe were always most readily removed, while Co and Mn were sorbed least readily. There were indications of competition for active sites (CO2H and phenolic OH groups) on the HA between the different metals. We were unable to find correlations between the affinities of the eleven metals to sorb on HA and their atomic weights, atomic numbers, valencies, and crystal and hydrated ionic radii. The sorption of the eleven metals on the HA could be described by the equation Full-size image (1K), where Y = % metal removed by HA; X = mgHA; and A and B are empirical constants

MOCVD生长的II-VI族化合物固溶体组分的热力学分析.2.Hg（1-x）CdxTe体系

对MOCVD生长Hg_(1-x)Cd_xTe进行了热力学分析.所用的起始原材料为Hg、DM-Cd和R_2Te.计算结果一方面表明CdTe优先并入倾向使得在通常的DAG工艺中x值非常不易控制.另一方表明即使在Hg存在的情况下,也可以沉积几平纯的CdTe,这对实现IMP工艺非常有利,计算结果还表明II/VI比对HgCdTe的组分控制起着关键性的作用.在DAG工艺中,较低的II/VI比可以改善对x值的控制能力,LMP-DAG工艺是降低II/VI比的较好途径.还计算了生长温度和反应室压力对固相组分的影响以及LMP-DAG工艺中生长温度与HgCdTe组分对最低汞分压的影响.

Extraction and separation of cadmium(II), iron(III), zinc(II), and europium(III) by Cyanex302 solutions using hollow fiber membrane modules

The mass transfer behaviors of Cd(II), Fe(III), Zn(II), and Eu(III) in sulfuric acid solution using microporous hollow fiber membrane (HFM) containing bis(2,4,4-trimethylpentyl)monothiophosphinic acid (commercial name Cyanex302) were investigated in this paper. The experimental results showed that the values of the mass transfer coefficients (K-w) decreased with an increase of H+ concentration and increased with an increase of extractant Cyanex302 concentration. The mass transfer resistance of Eu3+ was the largest because K-w value of Eu3+ was the smallest. The order of mass transfer rate of metal ions at low pH was Cd > Zn > Fe > Eu. Mixtures of Zn2+ and Eu3+ or of Zn2+ and Cd2+ were well separated in a counter-current circulation experiment using two modules connected in series at different initial acidity and concentration ratio. These results indicate that a hollow fiber membrane extractor is capable of separating the mixture compounds by controlling the acidity of the aqueous solution and by exploiting different mass transfer kinetics. The interfacial activity of Cyanex302 in sulfuric acid solution was measured and interfacial parameters were obtained according to Gibbs adsorption equation.

Facile separation and determination of Aconitine alkaloids in traditional Chinese medicines by CE with tris(2,2 '-bipyridyl) ruthenium(II)-based electrochemi-luminescence detection

A facile CE method coupled with tris(2,2'-bipyridyl) ruthenium(ll)-based electrochem iluminescence [Ru(bpy)(3)(2+)] detection was developed for simultaneous determination of Aconitum alkaloids, i.e., hypaconitine (HA), aconitine (AC), and mesaconitine (MA) in baseline separation. The optimal separation of these Aconitum alkaloids was achieved in a fused-silica capillary column (50 cm x 25 mu m id) with 30 mM phosphate solution (pH 8.40) as running buffer at 12 kV applied voltage. The three alkaloids can be determined within 10 min by a single run. The calibration curves showed a linear range from 2.0 x 10(-7) to 2.0 x 10(-5) M for HA, 3.4 x 10(-7) to 1.7 x 10(-5) M for AC, and 3.8 x 10(-7) to 1.9 x 10(-5) M for MA. The RSDs; for all analytes were below 3.01%. Good linear relationships were found with correlation coefficients for all analytes exceeding 0.993. The detection limits were 2.0 x 10(-8) M for HA, 1.7 x 10(-7) M for AC, and 1.9 x 10(-7) M for MA under optimal conditions. This method was successfully applied to determine the three alkaloids in Aconitum plants.

Separation of zinc(II) from europium(III) by using hollow fiber membrane

Extraction and separation of Eu3+ and Zn2+ in sulfuric acid solution was investigated by hollow fiber membrane with cyanex 302 (bis (2,4,4-trimethylpentyl) monothiophosphinic acid) in counter-currently circulating operation. Reaction mechanism of membrane extraction and effect of extractant concentration and H+ concentration in aqueous phase on the mass transfer coefficient were discussed. It can be concluded that Zn2+ can be extracted completely from Eu3+ sulfate solution according to the kinetics competing difference. In one extractor process, extraction percentage of Zn2+ was not completely and Eu3+ was not extracted. Extraction percentage of Zn2+ reached 94.92%, but Eu3+ only reached 8.59% after 100 minutes extraction in two series connectors and that of Zn2+ and Eu3+ reached 99.9% and 6.53% respectively after 40 minutes extraction in three series connectors.

Separation and determination of organogermanium compounds by ion chromatography

For nearly three decades, organogermanium compounds have become increasingly of interest owing to their extensive physiological and pharmaceutical activity. In this paper, two new high performance ion chromatographic methods for separation and determination of three kinds of organogermanium compounds beta-carboxyethylgermanium sesquioxide (I), beta-(alpha-methyl)-carboxyethylgermanium sesquioxide (II) and d-(beta-carboxyethyl)germanium hydroxide (III) were proposed. A Dionex DX-300 ion chromatograph equipped with a Dionex FED-II pulsed electrochemical detector (conductivity mode), and a Dionex AI-450 chromatography workstation was employed. The separation was achieved by using ion-exchange or ion-exclusion mechanism. The detection limits(S/N=3, expressed as germanium) for the three compounds were all below sub- mu g/mL level. The methods have been applied to the analysis of tonic oral drinks, and the average recoveries for the three compounds range from 95 - 108%. The results obtained were in agreement with those of hydride generation atomic fluorescence spectrometry (HG-AFS).

Toughness Of Ni/Al2O3 Interfaces As Dependent On Micron-Scale Plasticity And Atomistic-Scale Separation

Ceramic/metal interfaces were studied that fail by atomistic separation accompanied by plastic dissipation in the metal. The macroscopic toughness of the specific Ni alloy/Al2O3 interface considered is typically on the order of ten times the atomistic work of separation in mode I and even higher if combinations of mode I and mode II act on the interface. Inputs to the computational model of interface toughness are: (i) strain gradient plasticity applied to the Ni alloy with a length parameter determined by an indentation test, and (ii) a potential characterizing mixed mode separation of the interface fit to atomistic results. The roles of the several length parameters in the strain gradient plasticity are determined for indentation and crack growth. One of the parameters is shown to be of dominant importance, thus establishing that indentation can be used to measure the relevant length parameter. Recent results for separation of Ni/Al2O3 interfaces computed by atomistic methods are reviewed, including a set of results computed for mixed mode separation. An approximate potential fit to these results is characterized by the work of separation, the peak separation stress for normal separation and the traction-displacement relation in pure shearing of the interface. With these inputs, the model for steady-state crack growth is used to compute the toughness of the interface under mode I and under the full range of mode mix. The effect of interface strength and the work of separation on macroscopic toughness is computed. Fundamental implications for plasticity-enhanced toughness emerge.

Sequence of mitochondrial DNA cytochrome oxidase II in Cryptopygus nanjiensis and phylogeny of apterygota

The mitochondrial cytochrome oxidase II (Co II) from four different apterygotens Cryptopygus nanjiensis (Collembola), Neanura latior (Collembola), Gracilentulus maijiawensis (Protura) and Lepidocampa weberi (Diplura) were sequenced. Their A+T content, number of nucleotide substitutions, TV/TV ratio; and Tamura-Nei's distance were calculated. A series of phylogenetic trees were constructed by parsimony and distance methods using a crustacean Artemia franciscana as outgroup, Finally the evolutionary trend A+T content of CO II genetic divergence and phylogenetic relationship of apterygotan groups were discussed.

Monte Carlo simulation of the neutron detection wall at RIBLL II in HIRFL-CSR

With the construction of the new Radioactive Ion Beam Line in Lanzhou (RIBLL II) which connects the CSRm and the CSRe, an experimental setup for physics research is highly required. A large area neutron detection wall is the main part of the setup. This paper introduced the detection principle of the neutron detection wall and the Monte-Carlo simulation of its design under the environment of the Geant4 toolkit. We presented the final design with the optimized parameters and the performance of the wall.

Selective Extraction of Mercury(II) by 1-Naphthylthiourea-Methyl Isobutyl Ketone System

Selective extraction of Mercury(II) using 1-naphthylthiourea-methyl isobutyl ketone (ANTU-MIBK) system from hydrochloric acid solutions (0.1-10 M) has been studied. Influence of foreign ions, acid and ligand concentrations has been investigated. Addition of ANTU in MIBK enhanced, extraction capacity of MIBK to several times. Low effect of foreign ions and high separation factors for a number of metal ions determined at 0.5 M hydrochloric acid concentration evaluated the proposed method efficient and selective. The experimental data obtained from application of the method for extraction of mercury from a synthetic aqueous solution reveal that more than 99% mercury can be separated from cadmium, zinc and selenium in a single step with five minutes equilibration

Analysis of quinolizidine alkaloids in Sophora flavescens Ait. by capillary electrophoresis with tris(2,2 '-bipyridyl) ruthenium (II)-based electrochemiluminescence detection

A capillary electrophoresis method coupled with electrochemiluminescence detection for the analysis of quinolizidine alkaloids was established, especially, oxymatrine (OMT) which could not be measured by previous electrochemiluminescence methods was detected sensitively herein. Complete separation of sophoridine (SR), matrine (MT) and OMT was achieved within 13 min using a background electrolyte of 50mM phosphate buffer at pH 8.4 and a separation voltage of 15 kV. The calibration curves showed a linear range from 2.8 x 10(-8) to 4.4 x 10(-7) M for SR, 2.7 x 10(-8) to 4.4 x 10(-7) M for MT.

Simultaneous determination of pethidine and methadone by capillary electrophoresis with electrochemiluminescence detection of tris(2,2 '-bipyridyl)ruthenium(II)

In this paper, we described a simple and rapid method, capillary electrophoresis with electrochemiluminescence (CE-ECL) detection using tris(2,2'-bipyridyl)ruthenium(II) (Ru(bpy)(3)(2+)), to simultaneously detect pethidine and methadone. Analytes were injected to separation capillary of 67.5 cm length (25 mu m i.d., 360 mu m o.d.) by electrokinetic injection for 10 s at 10 kV.

CEC with tris(2,2 '-bipyridyl) ruthenium(II) electrochemiluminescent detection

For the first time, CEC was coupled with tris(2,2-bipyridyl) ruthenium(II) (Ru(bpy)(3)(2+) electrochemiluminescence detection. Efficient CEC separations of proline, putrescine, spermidine and spermine were achieved when the pH of the mobile phase is in the range of 3.5-7.0. The optimum mobile phase for CEC separation is much less acidic than that for CZE separation, which matches better with the optimum pH for Ru(bpy)(3)(2+) electrochemiluminescence detection and dramatically shortens the analysis time because of larger EOF at higher pH.