Simultaneous determination of some trace metal impurities in high-purity sodium tungstate using coprecipitation and inductively coupled plasma atomic emission spectrometry

A method based on the combination of coprecipitation with inductively coupledplasma atomic emission spectrometry (ICP-AES) was developed for the determination of impurities inhigh-purity sodium tungstate. Six elements (Co, Cu, Fe, Mn, Ni, and Pb) were coprecipitated bylanthanum hydroxide so as to be concentrated and separated from the tungsten matrix. Effects of somefactors on the recoveries of the analytes and on the residual amount of sodium tungstate wereinvestigated, and the optimum conditions for the coprecipitation were proposed. Matrix-matchingcalibration curve method was used for the analysis. It is shown that the elements mentioned abovecan be quantitatively recovered. The detection limits for Co, Cu, Fe, Mn, Ni, and Pb are 0.07, 0.4,0.2, 0.1, 0.6, and 1.3 μg·g^(-1), respectively. The recoveries vary from 92.5% to 108%, and therelative standard deviations (RSDs) are in the range of 3.1%-5.5%.

Reagent optimization for on-line simultaneous polarographic determination of trace amounts of Cu^(2+), Cd^(2+) and Co^(2+) in the presence of anextremely large excess of Zn^(2+)

Reagents are optimized for the simultaneous determination of trace amounts of Cu^(2+), Cd^(2+) and Co^(2+) in zinc sulfate solution, which contains an extremely large excess of Zn^(2+). First, the reagents and their doses for the experiment are selected according to the characteristics of the zinc sulfate solution. Then, the reagent doses are optimized by analyzing the influence of reagent dose on the polarographic parameters(i.e. half-wave potential E_(1/2) and limiting diffusion current I_p). Finally, the optimization results are verified by simultaneously determining trace amounts of Cu^(2+), Cd^(2+) and Co^(2+) in the presence of an extremely large excess of Zn^(2+). The determination results indicate that the optimized reagents exhibit wide linearity, low detection limits, high accuracy and good precision for the simultaneous determination of trace amounts of Cu^(2+), Cd^(2+) and Co^(2+) in the presence of an extremely large excess of Zn^(2+).

Determination of Trace Impurities of Rare Earth Elements in High Purity Yttrium Oxide by ICPMS

Determination of trace rare earth elements(REEs)in 99. 999% purity yttrium oxide using the inductively coupled plasma mass spectrometric technique (ICPMS) has been developed. Instrumental parameters and factors affecitng analytical results have been studied and then optimized.Samples are analyzed directly following an acid digestion without separation or preconcentration and with limit of detection of 0. 003～0. 02 ng/ml, precision of ±5. 4%(cofficient of variation)and recovery of 90～115%. Correction for isobaric interferences from oxide ions and hydroxide ions is made mathematically. Special internal standard procedures are used to compensate drift in metal:metal oxide ratios and sensitivity. The analytical results of several samples are accurate as compared with inductively coupled plasma atomic emission spectrometry (ICPAES) and spark source mass spectrometry (SSMS).

Direct Determination of Trace Titanium in High Purity Yttrium Oxide by FETV/ICP-AES

Based on selective volatilization taking place among elements in graphite furnace, a new method for direct determination of trace titanium in high purity yttrium oxide by fluorination electrothermal vaporization(FETV)/ICP AES has been proposed. The vaporization behavior of the analyte and matrix element was studied in detail. Various factors of influence on vaporization of analyte were also investigated. Under optimal experimental conditions, the detection limit(3 σ ) of Ti is 1 0 ng/ml, and the RSD is 2 3%( n =10, c =0 2 μg/ml). The proposed method is simple, rapid and sensitive, and pretreatment is not necessary. This method can be used to directly determine trace refractory impurity titanium in high purity powder sample(Y 2O 3). The recovery for sample analysis is more than 96%.

A FLUORESCENCE QUENCHING IMNUNOASSAY METHOD FOR DETERMINATION OF TRACE ALBUMIN USING UNLABELED EUROPIUM CHELATE

A fluoroimmunoassay method using unlabeled europium chelate is described.The principle is similar to that of fluoroimmunoassay method using lanthanide chelate as labels.The procedure is simple because labeling process is omitted.The detection limit is about 10^(10) mol/L antigen.The relative standard deviation of immunoassay is less than 10%.The recoveries of human serum albumin and estradiol protein conjugate are 96-105% and 111% respectively.

INDIRECT VOLTAMMETRIC DETERMINATION OF TRACE SULFATE IN NATURAL WATERS WITH THE ADSORPTIVE COMPLEX WAVE OF LEAD(Ⅱ)-TETRAKIS (4-TRIMETHYLAMMONIUM PHENYL) PORPHYRIN

The indirect voltammetric determination of trace sulfate (2.0×10^(-6)～4.0×10^(-5) mol/L ) with the adsorptive complex wave of lead(Ⅱ)-tetrakis (4-trimethylammonium phenyl) porphyrin (PbTTMAPP) is reported.This method has been used for the analysis of natural waters with satisfactory results.

STUDIES ON DERIVATIVE FLUORIMETRY Ⅲ. DETERMINATION OF TRACE AMOUNT OF TERBIUM IN THE PRESENCE OF SODIUM DODECYL SULFONATE

The derivative fluorimetric characteristics of Tb—SDS and Tb—SDS—phenanthroline systems have been studied. The optimum conditions were obtained. The 2nd—derivative spectrofluorimetric method in the systems has been applied to the determination of trace amounts of terbium, in rare earth ore and their oxides. The results are satisfactory.

A QUENCHING FLUORESCENCE IMMUNOASSAY METHOD FOR DETERMINATION OF TRACE ALBUMIN USING UNLABELED TERBIUM CHELATE

A fluoroimmunoassay method using unlabeled Terbium chelate is described.The principle is similar to that of fluoroimmunoassay method using lanthanide chelate as labels.The procedure is simpte because labeling process is unnecessary.The recovery of HSA and albumin in urine is 107% and 95% respectively.The standard deviation is tess than 10%.

THE USE OF CHELATING RESIN FOR THE PRE-CONCENTRATION OF TRACE RARE EARTH ELEMENTS IN BIOLOGICAL SAMPLES AND THEIR DETERMINATION

Macroporous amino-carboxvlic chelating resin of acrylic acid series may concentrate trace rare earth in the presence of 0.1 mol/l α-hydroxy-isobutyric acid at pH 4.5.With 0.10 mol/l HCl as eluant rare earth may be eluted quantitatively and separated from Ca,Mg,Fe and Cu.This method is used to determine trace amount of rare earth in human hair,stone (in kidney and bladder),peanut,grape,strawberry,cucumber,pig liver and other biological samples.

STUDIES ON DERIVATIVE FLUORIMETRY Ⅳ. DETERMINATION OF TRACE AMOUNT OF TERBIUM THROUGH ITS TERNARY COMPLEX WITH ACETYLACETONE AND EDTA IN THE PRESENCE OF CETYL PYRIDINIUM CHLORIDE

Terbium can form a ternary complex having a ratio of 1:1:1 with acetylacetone and EDTA. By adding cetyl pyridinium chloride into the above system, a marked enhancement of fluorescence intensity is observed and the ternary complex becomes more stable than before. For analytical application, the derivative spectrofluorimetric method has high sensitivity and the effect of foreign ions is very low. The optimum conditions were obtained. The calibration graph is linear over 5～100μg/mL.

STUDY ON THE DETERMINATION OF TRACE BISMUTH(III) BY THIN-LAYER RESIN PHASE SPECTROPHOTOMETRY

In this paper, a new thin-layer ion-exchange resin phase analytical method is introduced. It is based on that, the bismuthous cation can associate with iodic anions, so as to formed an anion complex [BiI4-] in a strong acidic environments. This anion complex can also exchanges with a weaker anions on the surface active site of anion exchange resin, so that a [R+] [BiI4-] solid phase binary associational system is produced. Owing to the solid system is a great many dispersive particulates, it can be pressed to a thin-layer by press tools of the so called 搕hin-layer resin phase?or 搑esin phase? and using this solid association system spectrophotometry for the determination of trace metals. So it can increase the analytical sensitivity. This association system exhibits maximum absorbance at 460nm, and obeys Beer抯 law over the concentration range 0.01ug/ml^1.20ug/ml of bismuthous(III). It has a molar absorptivity of 7.1×105 [L/mol穋m]. It indicated the resin phase spectrophotometry is a sensitive analytical method for trace bismuthous. It is 18 times higher than routine aqueous spectrophotometry. The relative standard deviations is 1.82% (n=6) for the measurements of 0.5ug/ml Bi(III). The detection limit of Bismuthous(III) is 1.4×10-8mol/L. The method has applied to the analysis Bi(III) in environmental water samples.

Determination of trace lead in rice of sewage irrigation by graphite furnace atomic-absorption spectrometry

The early literatures reported that a lot of matrix interference were encounted in the determination of lead content in various samples. Chlorides produced serious interference on analysis of lead content. All acids except phosphoric acid reduced sensitivity of determination of Pb. Hinderberger et al.reported that lead was determined without the interference could be removed by using NH4H2PO4 as matrix modifier in L’vov platform atomization. The combination of pyrolytic graphite tube with solid pyrolytic graphite platform and Zeeman background correction technique was used in our experiments for determination of lead content in rice samples, with 0.1% Mg(NO)and 2% NHHPOas matrix modifier.

晶体海绵技术的研究进展

有机小分子的结构分析,往往超出了光谱技术的分析能力,为了充分表征其结构,单晶X射线衍射方法是可用的最强大的工具之一,可以在原子水平上提供分子的结构,然而,该方法很大程度上依赖于高质量的晶体,限制了其广泛应用。近年来,新兴的晶体海绵技术(crystalline sponge, CS)打破了单晶衍射必须应用于结晶化合物的局限性,采用了一种金属有机框架(metal organic frameworks, MOFs),将一些难结晶、含量低的小分子化合物有序包合在其空腔内,使其结构确定成为可能。综述了晶体海绵技术的发展、原理、实际操作步骤及应用范围,并讨论了该技术的相对优势和局限性,为微量化合物绝对构型的确定提供参考与借鉴。

Exogenous Selenium Mitigates Salt Stress in Soybean by Improving Growth,Physiology,Glutathione Homeostasis and Antioxidant Defense

The mechanism of selenium(Se)-induced salt tolerance was studied in moderately sensitive soybean(Glycine max L.)plants.To execute this view,soybean plants were imposed with salt stress(EC 6 dS m^(−1))applying NaCl.In other treatments,Se(0,25,50 and 75μM Na_(2)SeO_(4))was sprayed as co-application with that level of salt stress.Plant height,stem diameter,leaf area,SPAD value decreased noticeably under salt stress.Altered proline(Pro)level,together with decreased leaf relative water content(RWC)was observed in salt-affected plants.Salt stress resulted in brutal oxidative damage and increased the content of H_(2)O_(2),MDA level and electrolyte leakage.Exogenous Se spray alleviated oxidative damage through boosting up the antioxidant defense system by increasing the activity of antioxidant enzymes such as catalase(CAT),peroxidase(POD)and glutathione reductase(GR),as well as by improving non-enzymatic antioxidants like glutathione(GSH)and GSH/glutathione disulfide(GSSG).The upregulated antioxidant defense system,restored Pro and leaf RWC,higher SPAD value conferred better growth and development in Se-sprayed salt-affected soybean plants which altogether put forth for the progressive yield contributing parameters and finally,seed yield.Among different doses of Se,soybean plants sprayed with 50μM Na_(2)SeO_(4)showed better salt tolerance.

Effects of Different Selenium Application Methods on Wheat (Triticum aestivum L.) Biofortification and Nutritional Quality

Mineral nutrient malnutrition,especially deficiency in selenium(Se),affects the health of approximately 1 billion people worldwide.Wheat,a staple food crop,plays an important role in producing Se-enriched foodstuffs to increase the Se intake of humans.This study aimed to evaluate the effects of different Se application methods on grain yield and nutritional quality,grain Se absorption and accumulation,as well as 14 other trace elements concentrations in wheat grains.A sand culture experiment was conducted via a completely randomized 3×2×1 factorial scheme(three Se levels×two methods of Se application,foliar or soil×one Se sources,selenite),with two wheat cultivars(Guizi No.1,Chinese Spring).The results showed that both foliar Se and soil Se application methods had effects on wheat pollination.Foliar Se application resulted in early flowering of wheat,while soil Se application caused early flowering of wheat at low Se levels(5 mg kg^(−1))and delayed wheat flowering at high selenium levels(10 mg kg^(−1)),respectively.For trace elements,human essential trace elements(Fe,Zn,Mn,Cu,Cr,Mo,Co and Ni)concentrations in wheat grains were dependent of Se applica-tion methods and wheat cultivars.However,toxic trace elements(Cd,Pb,Hg,As,Li and Al)concentrations can be decreased by both methods,indicating a possible antagonistic effect.Moreover,both methods increased Se concentrations,and improved grain yield and nutritional quality,while the foliar application was better than soil.Accordingly,this study provided useful information concerning nutritional biofortification of wheat,indicating that it is feasible to apply Se to conduct Se biofortification,inhibit the heavy metal elements concentrations and improve yield and quality in crops,which caused human health benefits.

Toxicological effects of nanoselenium in animals

The productivity and sustainability of livestock production systems are heavily influenced by animal nutrition.To maintain homeostatic balance in the body of the animal at different phases of life,the percentage of organically active minerals in livestock feed must be optimized.Selenium(Se)is a crucial trace mineral that is required for the maintenance of many functions of the body.Se nanoparticles(SeNPs)attracted considerable interest from researchers for a variety of applications a decade ago,owing to their extraordinary properties.SeNPs offer significant advantages over larger-sized materials,by having a comparatively wider surface area,increased surface energy,and high volume.Despite its benefits,SeNP also has toxic effects,therefore safety concerns must be taken for a successful application.The toxicological effects of SeNPs in animals are characterized by weight loss,and increased mortality rate.A safe-by-strategy to certify animal,human and environmental safety will contribute to an early diagnosis of all risks associated with SeNPs.This review is aimed at describing the beneficial uses and potential toxicity of SeNPs in various animals.It will also serve as a summary of different levels of SeNPs which should be added in the feed of animals for better performance.

Trace of Positive Integer Power of Real 2 ×2 Matrices

The purpose of this paper is to discuss the theorems for the trace of any positive integer power of 2 × 2 real matrix. We obtain a new formula to compute trace of any positive integer power of 2 × 2 real matrix A, in the terms of Trace of A (TrA) and Determinant of A (DetA), which are based on definition of trace of matrix and multiplication of the matrixn times, where n is positive integer and this formula gives some corollary for TrAn when TrA or DetA are zero.

The Effect of Hemin and Deferoxamine on Selenium, Zinc, and Iron Levels of K562 Cells

This study investigated contents of trace elements selenium, zinc and iron both in control K562 cells, human leukemia cell line, and cells treated with hemin or the iron chelator deferoxamine cells. K562 cell line was grown in RPMI medium supplemented with 10% fetal calf serum, 100 IU/mL penicillin, 100 μg/mL streptomycin, 25 μg/mL amphotericin B and 2 mM L-glutamine at 37?C in humidified air containing 5% CO2. K562 cells were treated with hemin and deferoxamine from the first day to the fifth day. The trace element levels were measured by inductively coupled plasma optical emission spectrometry. Treatment of K562 cells with hemin resulted in an increase in the levels of selenium on fifth day compared with first day. No differences were observed in selenium levels of the control group compared with the hemin-induced group. Also there were no significant differences observed in the zinc levels of control cells compared with deferoxamine- and hemin-induced cells. Iron levels of hemin-induced cells were decreased on the fourth day com-pared with the third day. On the third day, iron levels of hemin-induced cells were significantly increased compared to the control group. Our observations suggest that alterations of selenium and zinc levels may play a role in hemin-induction and deferoxamine-inhibition, respectively. On the other hand, iron levels may influence both in hemin-induction and deferoxamine-inhibition of K562 human leukemia cell

Distribution and Accumulation of Major and Trace Elements in Gypsum Samples from Lignite Combustion Power Plant

Flue gas containing volatile elements, fine fly ash particulates not retained by particle control devices, and limestone are the most important sources of trace and major elements (TMEs) in wet flue gas desulphurization (WFGD) gypsum. In this study, samples of gypsum slurry were separated into fine and coarse fractions. Multi-elemental analysis of 45 elements in the different size fractions of gypsum, slurry waters and lignite were performed by k0-INAA (k0-instrumental neutron activation analyses). The study found that the volatile elements (Hg, Se and halogens) in the flue gas accumulate in the fine fractions of gypsum. Moreover, the concentrations of most TMEs are considerably higher in the fine fractions compared to the coarse fractions. The exceptions are Ca and Sr that primarily originate from the limestone. Variations of TMEs in the finer fractions are dependent on the presence of CaSO4·2H2O that is the main constituent of the coarse fraction. Consequently, the content of TMEs in the fine fraction is highly dependent on the efficiency of separating the fine fraction from the coarse fraction. Separation of the finer fraction, representing about 10% of the total gypsum, offers the possibility to remove effectively TMEs from WFGD slurry.

Resonance luminescence spectra of selenium （Ⅳ）—iodide—rhodamie B sy

Ｒｅｓｏｎａｎｃｅｌｕｍｉｎｅｓｃｅｎｃｅｓｐｅｃｔｒａｏｆｓｅｌｅｎｉｕｍ（Ⅳ）－ｉｏｄｉｄｅ－ｒｈｏｄａｍｉｅＢｓｙｓｔｅｍａｎｄｉｔｓ ａｎａｌｙｔｉｃａｌａｐｐｌｉｃａｔｉｏｎ￥ＬｉｕＳｈａｏｐｕ；ＬｉｕＺｈｏｎｇｆａｎｇ；ＬｉＭｉｎｇ（Ｓｃ...