钒钼黄分光光度法测定有机化合物中的微量磷

介绍了钒钼黄分光光度法测定有机化合物中微量磷的方法。有机磷经浓硫酸-硝酸氧化分解,转化为正磷酸。在一定酸度下,溶液中的磷与偏钒酸盐和钼酸盐作用,形成稳定的黄色三元杂多酸钒钼磷酸,再用分光光度法测定磷含量。     

应用最小二乘法于壳聚糖测定的数据处理

应用紫外分光光度法和旋光法分别测定了壳聚糖的含量.在建立壳聚糖浓度与吸光度(紫外分光光度法)及壳聚糖浓度与旋光度(旋光法)之间的线性方程中,采用最小二乘法(LS法)对相关数据进行了处理.试验结果所示:用LS法所得上述两种测定方法的拟合曲线得出的测定结果,与常规方法所得曲线相比,具有更高的精密度和准确度.再者,两种测定方法的拟合曲线相比较,紫外分光光度法的曲线具有更高的精密度.     

分光光度法直接测定天然水中微量钼

本文研究了罗丹明B与硫氰酸钼形成红色络合物的问题,提出了分光光度法直接测定天然水中微量钼的新方法,方法灵敏(_600~ε=1.88×10~5)干扰少,相对标准偏差小于7%。检出限为2ppb。     

苯基荧光酮-曲通X-100光度法联测钢铁中微量钛及低含量钼

本文研究了以钛(钼)-苯基荧光酮-曲通X-100体系在水溶液中测定微量钛和低含量钼的分光光度法。方法灵敏度高,钛、钼有色络合物的最大吸收分别位于535nm,525nm处,其摩尔吸光系数分别为1.5×10~5,4.05×10~4,符合比尔定律的范围是:Ti:0—6μg/25mL,Mo:0—22μg/25mL。本法简便并具有较好的准确性、再现性和稳定性,适用於钢铁中微量钛及低含量钼的直接分光光度测定。     

过氧化氢氧化硫酸耐尔蓝催化褪色光度法测定痕量硅

测定痕量硅的方法有硅钼蓝光度法、间接原子吸收光谱法、硅钼蓝杂多酸极谱法、流动注射示差动力学化学发光法、硅钼蓝．罗丹明B离子缔合物分光光度法、阻抑．褪色光度法、硅锑钼杂多酸．罗丹明B四元络合体系光度法、乙基罗丹明B-硅钼杂多酸．PVA光度法、乙基罗丹明B-硅钼杂多酸．阿拉伯树胶体系分光光度法及停流流动注射化学发光法,未见     

邻苯二酚紫-溴化十六烷基吡啶分光光度法测定钢中钼

常用的硫氰酸盐光度法测定钢中钼灵敏度较低。对微量钼且须富集或萃取。近年来,对阳离子表面活性剂存在下,邻苯二酚紫光度法测定钼已有报导。本文采用在溴化十六烷基吡啶(CPB)存在下,邻苯二酚紫(PV)分光光度法直接在水溶液中测定钼。并用抗坏血酸(AK)、KF-EDTA掩蔽共存元素的干扰。对六种含钼量为0.005-0.56％的普碳钢及低合金钢标样测定均获得满意结果。本方法钼浓度在25—150微克/50毫升范围内符合比尔定律,比现行的硫氰酸盐光度法更为快速、灵敏、简便,适于测定普碳钢及低合金钢中钼的含量。 1.主要试剂:(1)10％AK(现用现配);     

色层分离-溴邻苯三酚红-溴代十六烷基三甲胺光度法测定纯铁及钢中微量钼

我们在活性氧化铝色层分离的工作中,观察到活性氧化铝对MoO_4~(2-)的吸附作用,并研究了钼的色层分离条件。提出了使用小型活性氧化铝色层吸附柱(简称吸附柱)分离富集微量钼,并消除部份离子对“胶束增溶分光光度法测定钼”的干扰。本文以CTMAB作为阳离子活性剂,在酸性溶液中同溴邻苯三酚红与钼形成蓝色的三元络合物,研究了其光度测定条件。拟定了色层分离光度测定纯铁及钢中微量钼的方法。本法的灵敏度高、重现性与准确度良好,但不适用于含钨试样的     

在非离子表面活性剂存在下,孔雀绿-磷钼杂多酸缔合物分光光度法测定微量磷

文献报导了基于利用非离子表面活性剂胶束增溶离子对缔合物所建立的水相测磷、砷和锗的分光光度法,为发展此类高灵敏度的显色反应和扩大非离子表面活性剂在光度分析中的应用提供了新的途径。本文研究在乳化剂OP存在下,孔雀绿-磷钼杂多酸缔合物分光光度法测定微量磷。为非离子表面活性剂对离子对缔合物的增溶作用又提供了一例。     

CTAB—苯芴酮法测定微量钼

自阳离子表面活性剂应用于分析化学中以来,曾对许多显色剂在长链季铵盐存在下测定微量钼进行了一系列工作,但有色络合物的克分子吸收系数均未达到10~5数量级。本文在前报基础上对苯芴酮在溴化十六烷基三甲基铵(以下简称CTAB)存在下胶束增溶分光光度法测定微量钼进行了详细的研究,使测钼的克分子吸收系数达到1.03×10~5。比资料报导的在氯化十六烷基吡啶存在下,采用同     

二溴棓因分光光度法测定矿石、钢铁中的钼——以辛可宁-钨消除钨的干扰

二溴棓因分光光度法测定微量钼是近几年提出的一种较新的测定方法,方法灵敏度高,稳定性好,许多阴、阳离子都不干扰,操作简便。但是,钨的允存量仅20微克,对钛、锡及常见的铁等元素的干扰未     

Determination of selenium in water by electrothermal atomic absorption spectrometry

Summary The electrothermal atomization of selenium has been investigated for the accurate determination of selenium in water samples. Hydrogen seriously affects the atomization temperature of selenium in a molybdenum micro-tube atomizer. The atomization of selenium also suffers from serious interferences caused by salts and other elements. The extraction of selenium diethyldithiocarbamate complex serves to eliminate the interferences from the matrix. The addition of copper allows the suppression of interferences from elements extracted with selenium. The method permits the determination of selenium(IV) and selenium(VI) separately.This research was in part funded by the Ministry of Education, Science and Culture, Japan, under Grant-in-Aid for Scientific Research, for which we express our appreciation.     

Matrix modification by Cu(NO3)2 for the determination of gold by electrothermal atomic absorption spectrometry with a molybdenum tube atomizer

Matrix modification by copper nitrate in electrothermal atomic absorption Spectrometry (ETAAS) of gold with a molybdenum tube atomizer has been investigated. The addition of copper nitrate served to eliminate the interferences from 10⁴–10⁵-fold concentrations of foreign elements at the 890 °C pyrolysis temperature. The absolute characteristic mass (giving 0.0044 absorbance) of gold in the presence of copper nitrate with the Mo atomizer was 0.26 pg and the detection limit was 38 pg/ml. These values were several times better than those obtained with graphite atomizers. The recovery of spiked gold in biological materials was in the range 96–106%. A sensitive and accurate ETAAS method was developed for complex matrix samples.     

The rapid colorimetric determination of molybdenum with dithiol in biological, geochemical and steel samples.

A rapid method for the determination of molybdenum in botanical, biological, geochemical and steel samples with dithiol, is described. Botanical and biological samples are ashed at 550 °C before leaching with 4 M hydrochloric acid, while geochemical samples are fused with potassium hydrogensulphate, and steels are decomposed with nitric and hydrochloric acids. The dithiol complex of molybdenum is formed by the addition of an alkaline solution of dithiol to the sample solution, and then extracted into isoamyl acetate. Ascorbic acid and citric acid are used to eliminate interferences from iron and tungsten, and the addition of potassium iodide gives the procedure very high tolerance to copper. Up to 150 geochemical samples or ashed botanical or biological samples can be analysed per man-day. Sensitivity of the method is 0.05, 0.5 and 10 p.p.m. for biological, geochemical and steel samples, respectively. The relative standard deviation is better than ±7% over the standard range used, and recovery of added molybdenum is complete.     

Determination of gold in biological materials by electrothermal atomic absorption spectrometry with a molybdenum tube atomizer

Electrothermal atomic absorption spectrometry (ETA-ASS) of gold with a molybdenum tube atomizer has been investigated. A sensitive ETA-AAS method was developed. The gold absorption signal became higher with the heating rate of the tube atomizer and as the ratio of hydrogen in the argon purge gas decreased. The optimal heating rate and the optimal gas flow rate were 5.5 C/msec and Ar 480 ml/min + H(2) 20 ml/min, respectively. The absolute characteristic mass (the mass of element giving 0.0044 abs.) of gold by the atomizer was 1.8 pg and the detection limit was 130 pg/ml (3S/N). These values were > 10 times better than those obtained with graphite atomizers, ICP and ICP-MS. The interferences caused by large amounts of interferents were evaluated. The addition of thiourea served to eliminate severe interferences. The recovery of spiked gold in biological materials was in the range of 101-106%.     

Direct determination of cadmium in biological material using electrothermal atomization atomic absorption spectrometry with a metal tube atomizer and a matrix modifier

A direct determination of cadmium by electrothermal atomization atomic absorption spectrometry with a molybdenum tube atomizer has been investigated. Direct calibration method with cadmium standard solutions and ultrasonic agitation method of a solution including sample powder were used. Sulfur served as a matrix modifier for removal of interferences. Though this direct analytical method for cadmium determination in biological materials had a relatively large standard deviation, the accuracy was similar or superior to those of a sample digestion method and the direct analysis without sulfur. The advantages of this method are its simplicity, low cost, high speed of analysis, and rapid calibration.     

Spectrophotometric reaction rate method for the determination of molybdenum by its catalytic effect on the oxidation of pyrogallol red with hydrogen peroxide

A kinetic spectrophotometric method for the determination of molybdenum is based on its catalytic effect on the oxidation of pyrogallol red with hydrogen peroxide. The decrease of the absorbance of pyrogallol red in the presence of hydrogen peroxide with time from 0.5 to 4.5 min is proportional to the concentration of Mo(VI) over the range 0.010–0.500 μg/mL. The limit of detection is 0.008 μg Mo/mL. The precision and the effect of the presence of more than forty ions on the molybdenum determination are reported. Probable interferences are completely removed by a cation exchange resin. The procedure was successfully applied to the determination of molybdenum in plant materials and steels. Received: 28 April 1997 / Revised: 16 June 1997 / Accepted: 18 June 1997     

Spectrophotometric reaction rate method for the determination of molybdenum by its catalytic effect on the oxidation of pyrogallol red with hydrogen peroxide

A kinetic spectrophotometric method for the determination of molybdenum is based on its catalytic effect on the oxidation of pyrogallol red with hydrogen peroxide. The decrease of the absorbance of pyrogallol red in the presence of hydrogen peroxide with time from 0.5 to 4.5 min is proportional to the concentration of Mo(VI) over the range 0.010–0.500 μg/mL. The limit of detection is 0.008 μg Mo/mL. The precision and the effect of the presence of more than forty ions on the molybdenum determination are reported. Probable interferences are completely removed by a cation exchange resin. The procedure was successfully applied to the determination of molybdenum in plant materials and steels. Received: 28 April 1997 / Revised: 16 June 1997 / Accepted: 18 June 1997     

Enhanced sensitivity for the differential pulse polarographic determination of Mo(VI) based on adsorption catalytic current

A differential pulse polarographic (DPP) method based on the adsorption catalytic current in a medium containing chlorate and 8-hydroxyquinoline (oxine) is suggested for the determination of molybdenum(VI). Experimental conditions such as pH and the composition of supporting electrolyte have been optimized to get a linear calibration graph at trace levels of Mo(VI). The sensitivity for molybdenum can be considerably enhanced by this method. The influence of possible interferences on the catalytic current has been investigated. The sensitivity of the method is compared with those obtained for other DPP methods for molybdenum. A detection limit of 1.0 × 10^–8 mol/L has been found.     

New method for removal of spectral interferences for beryllium assay using inductively coupled plasma atomic emission spectrometry

Beryllium (Be) has been used widely in specific areas of nuclear technology. Frequent monitoring of air and possible contaminated surfaces in U.S. Department of Energy (DOE) facilities is required to identify potential health risks and to protect U.S. DOE workers from beryllium-contaminated dust. A new method has been developed to rapidly remove spectral interferences prior to beryllium measurement by inductively coupled plasma atomic emission spectrometry (ICP-AES) that allows lower detection limits. The ion exchange separation removes uranium (U), plutonium (Pu), thorium (Th), niobium (Nb), vanadium (V), molybdenum (Mo), zirconium (Zr), tungsten (W), iron (Fe), chromium (Cr), cerium (Ce), erbium (Er) and titanium (Ti). A stacked column consisting of Diphonix Resin and TEVA Resin reduces the levels of the spectral interferences so that low level Be measurements can be performed accurately. If necessary, an additional anion exchange separation can be used for further removal of interferences, particularly chromium. The method has been tested using spiked filters, spiked wipe samples and certified reference material (CRM) standards with high levels of interferences added. The method provides very efficient removal of spectral interferences with very good accuracy and precision for beryllium on filters or wipes. This new method offers improvements over other separation methods that have been used by removing large amounts of all the significant spectral interferences with greater simplicity and effectiveness. The effective removal of spectral interferences allows lower method detection limits (MDL) using inductively coupled atomic emission spectrometry. A vacuum box system is employed to reduce analytical time and reduce labor costs.     

铈量法快速测定镍钼矿硫酸介质加压浸出液中的钼

镍钼浸出液中的大量Fe^2＋和Fe^3＋,采用氢氧化钠沉淀分离,以消除铈量法在测定钼时产生的干扰。通过在钼标准中加入Ni试验证明,测定体系中存在大量Ni^2＋时,不干扰钼的测定。用草酸一硫酸联氨将Mo^6＋还原至Mo^5＋,用次甲基蓝作氧化促进剂,加快了滴定时的反应速度,终点突跃明显。拟定方法的样品加标回收率为95．0％～103．5％,相对标准偏差均〈1％。在实际测定中,方法快速准确,值得推荐。