A new sensitive method for the spectrophotometric determination of molybdenum using 3-hydroxy-2-(2'-thienyl)-4H-chromen-4-one

A spectrophotometric method has been developed for the determination of Molybdenum (VI) using 3-hydroxy-2-(2'-thienyl)-4H-chromen-4-one as a complexing agent. The complex formed was dissolved in water in the presence of Triton X-100 and exhibits an absorption maximum at 410 nm. A large number of metal ions like Co(II), Ni(II), Mn(II), Cr(III), Zn(II), Cu(II), Hg(II), Bi(III), Fe(II), Fe(III), Zr(IV), V(V) can be tolerated at an appreciable concentrations. Molar absorptivity and Sandell's sensitivity of the method is 2.80 x 10(5) l mol-1cm-1 and 3.42 x 10(-4) micrograms cm-2, respectively. Beer's law is obeyed in the concentration range of 0.01-0.4 ppm Mo(VI). Aliquots containing 0.2 ppm of Mo(VI) give a mean absorbance of 0.56 with a relative standard deviation of 1.3%.     

用聚合表面活性剂作增敏试剂分光光度测定钼和钨

采用表面活性剂的分光光度分析法应用日趋广泛。这方面的研究工作虽极活跃,但较多工作限于已有经典表面活性剂的研究与应用,为分析化学的特定需要设计与合成新型表面活性剂的研究尚少。作者曾用环氧氯丙烷和长链烷基叔胺合成了以聚乙二醇为主链含有若干个带长链烷基的季氮支链的低聚合表面活性剂——聚(氧化丙烯)-α-十八烷基二甲基氯化铵(PPOSA)。实验表明,这类表面活性剂兼有阳离子和非离子表面活性剂的某些特性。本文     

N,N-diethyl-N'-benzoylthiourea--a new spectrophotometric reagent for rhenium determination

The reagent N,N-diethyl-N'-benzoylthiourea produces a green complex with rhenium in hydrochloric acid medium in the presence of tin(II) chloride. The complex extracted into toluene shows an absorption maximum at 383 nm, obeys Beer's law from 1.5 to 22 micrograms ml-1 of rhenium while its molar absorptivity and Sandell sensitivity are 6.66 x 10(3) L mol-1 cm-1 and 0.028 microgram cm-2, respectively. It tolerates the presence of a large number of ions, including Mo(VI), W(VI) and some platinum metals. Job's and the mole ratio methods indicate that the rhenium metal and the chelating agent ratio of 1:2 in solution. The system has been applied to the determination of rhenium on synthetic samples and alumina based catalysts.     

Selective and sensitized spectrophotometric determination of trace amounts of Ni(II) ion using alpha-benzyl dioxime in surfactant media

Highly sensitive and interference-free sensitized spectrophotometric method for the determination of Ni(II) ions is described. The method is based on the reaction between Ni(II) ion and benzyl dioxime in micellar media in the presence of sodium dodecyl sulfate (SDS). The absorbance is linear from 0.1 up to 25.0 microg mL-1 in aqueous solution with repeatability (RSD) of 1.0% at a concentration of 1 microg mL-1 and a detection limit of 0.12 ng mL-1 and molar absorption coefficient of 68,600L mol-1 cm-1. The influence of reaction variables including type and amount of surfactant, pH, and amount of ligand and complexation time and the effect of interfering ions are investigated. The proposed procedure was applied to the determination of trace amounts of Ni(II) ion in tap water, river water, chocolate and vegetable without separation or organic solvent extraction.     

Simultaneous determination of gallium and indium with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol in cationic micellar medium using derivative spectrophotometry.

A new derivative spectrophotometric method for rapid and selective trace analysis of Ga3+ and In3+ and for their simultaneous determination using 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol in a cationic micellar medium is reported. Molar absorptivity and Sandell's sensitivity of 1:1 Ga+ and In3+ complexes at their lambda(max) 553 nm and 558 nm are: 7.22 x 10(4) l mol(-1) cm(-1) and 5.85 x 10(4) l mol(-1) cm(-1), and 0.96 ng cm(-2) and 1.96 ng cm(-2), respectively. Linearity is observed in the concentration range 0.023-0.700 microg ml(-1) for gallium and 0.076-1.52 microg ml(-1) for indium; IUPAC detection limit is 0.012 and 0.035 ng ml(-1), respectively. These metal ions interfere with the determination of each other. However, 0.07-0.70 microg ml(-1) Ga3+ and 0.115-1.150 microg ml(-1) In3+ could be determined simultaneously when present together by the derivative method without any prior separation. The proposed procedures have been successfully applied for the individual and simultaneous determination of gallium and indium in synthetic binary mixtures, standard reference materials and environmental samples.     

人工神经网络吸光光度法同时测定钛和铌

确立了钛 4,5-二溴邻硝基苯基荧光酮 - CTMAB显色体系 ,在此基础上确立了钛和铌同时测定的显色体系 ,应用三层 ANN- BP网络解析钛和铌吸收光谱 ,吸光光度法同时测定铌和钛。方法选择性好 ,表观摩尔吸光系数 εTi557=1 .2 4× 1 0 5L· mol-1· cm-1,εNb54 0 =1 .63× 1 0 5L· mol-1·cm-1。对合金钢中铌和钛进行了同时测定 ,钛和铌的平均相对误差分别为 1 .30 %和 1 .0 8%。使用改进的 BP算法 ,避免了可能产生的麻痹现象。提出了便于网络参数选择的收敛评价函数。     

Development and application of spectrophotometric methods for the determination of citalopram hydrobromide in dosage forms

Study was carried out to develop two simple, fast, accurate and sensitive spectrophotometric methods (A and B) for the determination of citalopram hydrobromide in commercial tablet formulations. In method A, UV spectrophotometer determined the contents of citalopram hydrobromide in tablets at 240 nm in methanol solvent. The linear range was 5-40 microg ml-1 with molar absorptivity 1.4x10(4) l mol-1 cm-1. While the method B based on the reaction of citalopram base as n-electron donor with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone as pi-acceptors to give highly colored complex species that absorb maximally at 590 nm. Beer's law was obeyed in the concentration limit of 10-250 microg ml-1 with molar absorptivity 3.3x10(3) l mol-1 cm-1 for citalopram hydrobromide. The limits of detection and limit of quantification was calculated and found to be 5.2 microg ml-1 and 17.4 microg ml-1 respectively. The proposed methods were found to be rapid, accurate, precise and sensitive for the determination of citalopram hydrobromide in commercial tablet formulations with out interferences from common additives encountered.     

Simultaneous determination of uranium(VI) and thorium(IV) with carminic acid by derivative spectrophotometry

The reactions of uranium(VI) and thorium(IV) ions with carminic acid have been investigated. These ions react with carminic acid in neutral medium, forming colored complexes. The dark purple or red wine complexes show a high absorption in the visible region (597 nm U(VI) and 616 nm Th(IV)). Chemical variables that affect the reaction have been optimized. The spectral overlapping of the color of complexes has been resolved by first-derivative spectrophotometry. The simultaneous determination of uranium(VI) and thorium(IV) mixtures is accomplished by taking the derivative signal (zero crossing) at 597 nm for U(VI) determination and at 616 nm for Th(IV) determination, respectively. The method has been applied to Tyuyamonite ore, containing in the matrix both ions.     

Spectrophotometric determination of vanadium in different oxidation states with pyrogallol

Determination of vanadium at low concentrations is easily performed with pyrogallol as a ligand which forms a bluish-violet complex with vanadium(III), (IV) or (V). The colour of the bluish-violet complex (lambda(max) = 580 nm) contrasts well with the colour of both pyrogallol and vanadium. The complexes are stable for several hours. Beer's law is obeyed over the range 0-14 mug/ml vanadium at pH 6. The apparent molar absorptivity at 580 nm is (7.75 +/- 0.25) x 10(3)1.mole(-1).cm(-1). The effects of diverse ions on the determination of vanadium have been fully studied. Only Mo(VI) and W(VI) interfere seriously. The method is selective, sensitive and can be applied to the determination of total vanadium in a variety of samples.     

Simultaneous determination of zirconium and molybdenum by first-derivative spectrophotometry.

A first-derivative spectrophotometric method for the simultaneous determination of Zr and Mo with Alizarin Red S is described. Measurements were made at the zero-crossing wavelengths at 490.5 nm for Zr and 446.0 nm for Mo. The calibration graphs were linear at 0.5-20 and 0.5-13.0 microg ml(-1) for Zr and Mo, respectively. The possible interfering effects of various ions were studied. Only iron was interfered in this system. The validity of the method was examined by using some mixtures of Mo and Zr. The method was applied in different matrix in both presence and absence of some foreign metal ions.     

Test analysis method using ion pairs of pyrocatechol azo derivatives and trihydroxyfluorones with cetylpyridinium and their chelates with metal ions immobilized on paper

A two-stage procedure is proposed for the immobilization of ion pairs of pyrocatechol azo derivatives and trihydroxyfluorones and their chelates with metal ions on paper. It is demonstrated that ion pairs of phenylfluorone and thiazolylazopyrocatechol with cetylpyridinium can be used for the test determination of 0.01-10 mg/L Ti(IV), 0.05-20 mg/L Mo(VI), and 0.1–20 mg/L W(VI) and V(V) by the length of the colored zone of test strips after their contact with a test solution and for the determination of 0.01-0.5 mg/L Al and Mo(VI) and 0.001-0.1 mg/L Ti(IV) by the color intensity of reactive papers after passing a test solution. Chelates of Mo(VI) with tiazolylazopyrocatechol and of Sb(III) with phenylfluorone are used for the test determination of 0.01-1000 mg/L cationic surfactants. The selectivity of reactions is studied, and procedures are proposed for the determination of the above elements in different materials. The relative standard deviation of the results of analysis is no higher than 50%.     

Simultaneous derivative spectrophotometric determination of zinc and cadmium with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol in the presence of cetylpyridinium chloride.

A selective and sensitive derivative photometric method has been developed for the determination of trace amounts of Zn2+ with 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol in the presence of cetylpyridinium chloride, a cationic surfactant. The molar-absorption coefficient and analytical sensitivity of the 1:2 complex at 554 nm are 1.19 x 10(5) L mol(-1) cm(-1) and 0.56 ng mL(-1), respectively. The detection limit is 1.96 x 10(-2) ng mL(-1) and Beer's law is valid in the 0.02-0.66 microg mL(-1) range of Zn2+. The developed derivative procedure, using the zero-crossing measurement approach, is applied for the rapid and selective simultaneous determination of Zn2+ and Cd2+ in the range of 0.06-0.66 and 0.20-1.60 microg mL(-1), respectively. Complex matrices, including reference materials, environmental and biological samples and synthetic mixtures, have been successfully analyzed for trace amounts of the two metal ions.     

Spectrophotometric determination of vanadium in biological materials with N-benzylbenzohydroxamic acid

A spectrophotometric method for the determination of vanadium in biological materials with N-benzylbenzohydroxamic acid is proposed. The method is highly selective for vanadium and is free from rigid control of reaction conditions. No separation of iron prior to the determination of vanadium is necessary. Cu(II), Co(II), Ni, Mn(II), Cr(III), Ce(IV), Zr, Mo(VI), Ca, Sr, Ba, UO(2)(II) and many others metal ions do not interfere. Fairly large quantities of Ti(IV) and W(VI) are tolerated.     

新试剂5-(5-碘-2-吡啶偶氮)-2,4-二氨基甲苯高选择性分光光度法测定微量Pd(Ⅱ)

研究了新试剂5-(5-碘-2-吡啶偶氮)-2,4-二氨基甲苯(5-I-PADAT)与Pd(Ⅱ)的显色反应。实验结果表明,在0.6～1.8mol/L高氯酸介质中,于室温下放置10min,Pd(Ⅱ)与5-I-PADAT可形成1∶1蓝紫色络合物,其最大吸收波长位于583nm,表观摩尔吸光系数ε为7.2×104L·mol-1·cm-1,Pd(Ⅱ)的浓度在0～1.0μg·mL-1符合比耳定律。由于反应直接在强酸性介质中进行,而在此酸度下,其它金属离子几乎不能反应,因此具有极高的选择性。所拟方法操作简单、快速,可应用于合金、矿样和分子筛中微量钯的测定。     

Spectrophotometric study and extraction of niobium(V) complexes with catechol and its derivatives as ion-pairs with quaternary ammonium ions: Application to the separation of niobium from other refractory metal ions

The reactions of niobium(V) with catechol and several substituted derivatives were studied. Optimal conditions for colour development in the niobium(V)-catechol system are: pH 6.7–8.0, and heating at 85° for at least 6 min; the wavelength of maximal absorption is 365 nm, and the molar absorptivity is 1.02·10⁴. Catechol derivatives require lower temperatures and develop colours with niobium(V) in neutral or slightly acidic solutions. The best of the derivatives studied were 3-methyl-catechol and 4-chlorocatechol. Extraction of the ion-pairs formed between niobium-(V)-catechol and different quaternary ammonium ions, was studied with representative solvents. Similar studies were made on other refractory metal ions, i.e., Ti(IV), V(V), Mo(VI) and W(VI), under the optimal conditions for the reaction with niobium(V). Separations of binary (1:1) mixtures of niobium(V) with Ti(IV), V(V), Mo(VI) or W(VI) at the 5·10^-5M level were shown to be possible under the predicted conditions.     

Extractive-spectrophotometric determination of molybdenum with 4-unsubstituted-5-pyrazolones

A fairly sensitive and selective method for rapid determination of tracer amounts of molybdenum(V) as mixed-ligand complexes with thiocyanate and 4-unsubstituted-5-pyrazolones is described. The red complexes are extractable into chloroform from 1-5M hydrochloric or perchloric acid or 1-3M sulphuric arid media. The molar absorptivities are in the range 1.72-2.15 x 10(4)l.mole(-1).cm(-1) at 455 nm (lambda(max)). The method has been applied to the estimation of molybdenum in various synthetic and alloy-steel samples. In presence of excess of the reagent, Cu(II), Co(II), Mn(II), Fe(II), Fe(III), Al(III), Cr(III), Cr(VI), Ti(III), Ti(IV), Zr(IV), Hf(IV), V(III), V(IV), V(V), Nb(V), Ta(V), W(VI) and U(VI) do not interfere.     

Fluorescence quenching method for determination of trace tungsten in environmental samples with dibromohydroxyphenylfluorone

A highly sensitive and selective fluorescence quenching method has been developed for the determination of trace tungsten in environmental samples using dibromohydroxyphenylfluorone (DBHPF) as an emission reagent. In the presence of 0.04?mol/L of sulphuric acid and acetyltrimethylammonium bromide, tungsten(VI) reacts with DBHPF to form a 1?:?3 red complex within 5.0?min. In order for the DBHPF–tungsten(VI) complex to form, the fluorescence intensity of the reagent solution was quenched linearly by adding 0.1 to 1.0?µg of tungsten(VI) in 25?mL of solution. This was measured at 528?nm with excitation at 495?nm. In this work, a standard addition method was investigated and used for sample analysis. The decrease in fluorescence intensity of the reagent solution (ΔF) was linear for 0?～?0.9?µg of tungsten(VI) in 25?mL of solution, and the detection limit (3?s) of the standard addition method was found to be 0.012?ng/mL of tungsten(VI). The effects of various metal and nonmetal ions were studied in detail. The experiments clearly showed that most foreign ions can be tolerated in considerable amounts; in particular, 50-fold Mo(VI), V(V), Zr(VI) and Ti(IV) do not interfere, and the selectivity of the proposed method is better than other previously described methods. Moreover, the method proposed here is very stable and simple, the fluorescence intensity of the solution can remain almost unchanged for 2.0?h at room temperature, and the method has been used successfully to determine tungsten in environmental samples.     

Successive determinations of platinum(II) and selenium(IV) with 1,4-dibromo-2,3-diaminonaphthalene in aqueous micellar solutions.

Highly sensitive successive determinations for PtII and SeIV ions have been developed based upon reactions with 1,4-dibromo-2,3-diaminonaphthalene (Br2DAN), which forms a near-infrared (NIR) absorbing complex (epsilon = 1.2 x 10(5) l mol-1 cm-1 at 800 nm) and an emissive complex (ex. 386 nm, em. 604 nm) for PtII and SeIV ions, respectively, in acidic aqueous micellar solutions. In the presence of a cationic surfactant, cetyltrimethylammonium chloride, the detection limits for PtII and SeIV ions are 1.2 ng ml-1 (3 sigma) and 0.98 ng ml-1 (S/N = 3), respectively. Hydrobromic acid plays a key role to enhance the color development of the NIR-absorbing PtII complex. The influences of CuII and ZnII ions at the normal human serum levels are readily tolerated, and interference from FeIII ion at 35 mumol l-1 is circumvented by the addition of 50 mumol l-1 of polyaminocarboxylates, such as EDTA.     

Simultaneous capillary electrophoretic separation and detection of P(V) and As(V) As heteropoly-blue complexes

A capillary electrophoretic (CE) method was developed for the simultaneous determination of P(V) and As(V). A Mo(VI)-ascorbic acid reagent reacted with a mixture of trace amounts of P(V) and As(V) to form the corresponding heteropoly-blue complexes in 0.05 M acetate buffer (pH 3.5). When 0.05 M malonate buffer was used as a migration buffer, the peaks due to their migrations were well separated in the electropherogram, and the pre-column complex-formation reaction was applied to the simultaneous CE determination of P(V) and As(V) with direct UV detection at 220 nm. With the proposed method, the calibration curves were linear in the concentration range of 5 x 10(-7) - 1 x 10(-4) M, with a detection limit of 1 x 10(-7) M (a signal-to-noise ratio of 3). Interference from foreign ions was also discussed.     

Untersuchungen zur anwendung ternärer komplexe in der photometrie—I Die bestimmung des Titan(IV) mit Tiron in gegenwart von äthylendiamintetraessigsäure

Two model systems and three analytical procedures based on them have been investigated analytically and characterized statistically with the aim of evaluating the application of ternary complexes in photometry. From measurements on the systems Ti(IV), Tiron (TiR^8?₃, procedure I), Ti(IV), Tiron, EDTA (TiR^8?₃, procedure II), Ti(IV), Tiron, EDTA [TiO(HY)R^5?, procedure III], the molar absorptivities, standard deviations, coefficients of variation, calibration data, limits of detection and determination have been calculated, and the possible interferences of 45 ions have been examined. Procedure III is shown to be the least sensitive of the three, but to offer a higher selectivity towards titanium in the presence of Cr(III), Cu(II), Fe(III), Mn(II), Mo(VI), Ni(II), U(VI) and W(VI). The reasons for this are discussed, and some suggestions are offered concerning the intended application of ternary complexes.