对氨基二乙基苯胺全差示光度法测定微量铬

详细实验了铬（Ⅵ）与对氨基二乙基苯胺氧化显色反应的条件。实验结果表明：铬（Ⅵ）与对氨基二乙基苯胺反应形成的红色产物在５５４ｎｍ处有最大吸收。表观摩尔吸收系数为３．３×１０＾４Ｌｍｏｌ＾－１．ｃｍ＾－１线性范围为０－１．６ｍｇ／Ｌ。实验了采用全差示光度法测定水中铬的条件，用于某湖水中４．０７μｇ／Ｌ的铬测定时，相对标准偏差为３．４％。测定结果与二苯胺基脲法的测定结果相比令人满意。     

N,N-diethylaniline as hydrogen donor for determination of hydrogen peroxide catalyzed by metalloporphyrins as enzyme mimetic of peroxidase

Various metalloporphyrins have been used as a catalyst instead of the peroxidase for the determination of hydrogen peroxide by formation of a dye from N,N-diethylaniline (DBA) and 4-aminoantipyrine. The difference of relative catalytic activity was investigated between enzyme and enzyme mimetics. FeT(4-TAP)P [5, 10, 15, 20-tetrakis (4-trimethyl-ammoniumphenyl)-21H, 23H-porphine] was shown as the best enzyme mimetic for horseradish peroxidase (HRP) among metalloporphyrins tested. 0 to 7.0 × 10^–5 mol/L hydrogen peroxide was determined with good accuracy and reproducibility, and giving recovery of 99.7–100.7%. DEA was certified as a sensitive color reagent in enzyme mimetic assay of hydrogen peroxide, with the apparent molar absorptivity for hydrogen peroxide was 1.37 × 10⁴ L/mol·cm.     

Spectrophotometric studies of transcurium element halides and oxyhalides in the solid state

The present state of a microscale spectrophotometric technique is described. The unique advantages of applying both spectrophotometric and X-ray powder diffraction methods on the sample, in order to identify and characterize newly synthesized compounds, are also discussed. Analytical Chemistry Division, ORNL. Research sponsored by the Division of Physical Research, United States Energy Research and Development Administration under contracts with Union Carbide Corporation and the University of Tennessee (Knoxville).     

Specific Spectrophotometric Determination of Palladium with N,N'-Diphenylbenzimidoylthiourea

ABSTRACT

A specific method for the spectrophotometric determination of palladium with N.N'-diphenylbenzimidoylthiourea (DPB1TU) is described. The method in new, simple, rapid and applicable over 0.3-1.0 M HC1 and free from interferences of the precious metals i.e.

Ag, Au, Pt, Ir, Rh, Ru, Os. The value of molar absorptivity of the complex in the term of Pd is (2.50)x10⁴ L mole^?1 cm^?1at λ_max 365 nm in chloroform. The detection limit of the method at 3 σ a is 80 ppb Pd. The composition of the complex and effect of diverse ions in the determination of Pd are discussed. The application of the method has been tested for the analysis of the metal in catalytic material.     

Fluorescence quenching of anthracene by N,N-diethylaniline in the O/W microemulsion

Photoinduced electron-transfer system of anthracene-N,N-di-ethylaniline (DEA) was studied in the oil in water (O/W) mi-croemulsions formed by SDS (sodium dodecyl sulfate),BA (benzyl alcohol) and H2O.The time-resolved fluorescence study showed that the fluorescence quenching of the excited anthracene by DEA occurs at the interface of the O/W mi-croemulsions.Besides as the quencher of the excited anthracene,N,N-diethylaniline could act as a cosurfactant to change the structures of the microemulsions,just as BA did.The quenching rate constants for the different structures of the system were determined.     

Spectrophotometric determination of aluminium with stilbazo

The use of stilbazo as a spectrophotometric reagent for aluminium has been investigated. The reagent forms a stable coloured complex with aluminium showing an absorption maximum at 500 mμ. The system obeys Beer's law from 0.1–0.8 p.p.m. aluminium. The molar extinction coefficient and the stoichiometric composition of the coloured complex have been determined.     

Spectrophotometric determination of scandium with arsenazo

Arsenazo is used for the spectrophotometric determination of scandium in the range 10 to 50 μg. The absorbance is measured at 570 mμ and pH 6.1. A method is proposed for the successive determination of scandium and thorium. Scandium is separated from magnesium, calcium, rare earths, zirconium, fluoride, phosphate, and some other metals by extraction with TTA in xylene. Copper, aluminum, and iron(III) are removed by 8-quinolinol-chloroform extraction. Uranium(VI) is removed by anion exchange using hydrochloric acid. Thorium is separated from scandium by anion exchange using nitric acid.     

Spectrophotometric determination of titanium with salicylamidoxime

Summary A spectrophotometric method for determining small quantities of titanium by extraction of the yellow coloured titanium salicylamidoxime complex from an acetate buffer medium (Ph 4.5–7.0) with iso-butanol and measurement of the colour intensity at 400 m has been described. Beer's law is obeyed in the entire range of 0.25–15 g Ti per ml of the solvent. The effect of a large number of foreign anions and cations on the determination of titanium has been described.     

Spectrophotometric determination of platinum with o-phenylenediamine

Platinum(IV or II) reacts with o-phenylenediamine, at pH 6.5, to form light blue solutions having maximum absorption at 703 nm. The reaction, slow at room temperature, is complete in 3-4 min at temperatures near 100 degrees . Use of dimethylformamide in the solution prevents precipitation of the reaction product. The colour is stable for at least 24 hr. Effects of heating temperature and time, pH, reagent concentration, and other variables have been studied. The system conforms to Beer's law over the concentration range investigated. Optimum concentration range for measurement in 10-mm cells is 0.4-1.4 ppm of platinum; the molar absorptivity is 9.83 x 10(3) l. mole(-1). mm(-1). Interference from foreign ions has been evaluated, and methods for removal or masking of interferences have been tested. In the colour-forming reaction, platinum(IV) is reduced by the organic reagent to platinum(II), which is then complexed with the reagent. The metal : ligand ratio of 1 : 2 was indicated by solution spectrophotometric measurements, and was confirmed on the solid reaction product by elemental analysis and by mass spectrometric examination.     

Spectrophotometric determination of copper with cuproine

A study is devoted to the spectrophotometric determination of traces of copper with cuproine as reagent. After having determined the absorption spectrum of the complex, the authors have studied successively the partition coefficient water/ isoamyl alcohol ; the stability of the complex (colour); the influence of some factors: pH, foreign ions, temperature, the quality of isoamyl alcohol, excess reagent; and the validity of Beer's law. Two different calibration curves were determined, one based on complete extraction of the complex and the other based on an empirical method, which is very rapid. In both cases the mean square error is less than 1%.Finally, analysis methods were worked out for the determination of traces of copper in plants, animal tissues and blood, in water, in lamp-black and in steel.     

Spectrophotometric determination of molybdenum with lobeline

Lobeline hydrochloride has been tested as a reagent for molybdenum(V). Molybdenum(VI) is reduced with hydrazine sulfate in hydrochloric acid solution to Mo(V) only and complexed with thiocyanate and lobeline which is extracted with chloroform. In the paper experimental conditions for the formation of the ion pair of lobeline with molybdenum thiocyanate are described and the composition of this complex is given.     

Spectrophotometric determination of selenium with dithizone

Microgram amounts of selenium(IV) are determined by measuring the decrease in absorbance of dithizone in carbon tetrachloride solution at 620 nm. Relative standard deviations for samples containing 0.20 and 1.00 μg of selenium(IV) are 0.6% and 0.4%, respectively. Of several metals tested only copper (at the 1.0-μg level) and iron (at the 100-μg level) interfere but high concentrations of nitric or perchloric acid cause low results. A reinvestigation of the reaction of selenium(IV) with dithizone suggests a formula Se(HDz)₄ for the dithizonate.     

Spectrophotometric determination of hexafluoroarsenate with ferroin

A spectrophotometric method for the hexafluoroarsenate anion is described. The determination involves selective extraction of the tris(1,10-phenanthroline)iron(II) salt of the anion into n-butyronitrile, followed by measurement of the absorbance of the organic layer. The extracts give good Beer's law plots over a wide range of concentrations and more than 98% of the hexafluoroarsenate is removed in a single extraction. Interference studies were made on a number of anions.     

Spectrophotometric determination of molybdenum with phenylfluorone

Spectrophotometric studies on the reaction between molybdenum as molybdate (MoO₄^2?) and phenylfluorone are presented. The reaction conditions are optimized to develop an intense color (molar absorptivity is 3.8 × 10³) selective and sensitive for the Spectrophotometric determination of molybdenum. The absorbance is measured at 560 nm, at a pH of 1.5–3. The colored complex is stable for up to 24 hr, Beer's law is obeyed, over the concentration range of 1 to 4 μg/25 ml. The relative standard deviation is 2% and the sensitivity of the method is 1.60 × 10^?4 mg/ml.     

Spectrophotometric determination of nickel with p-acetylarsenazo

A spectrophotometric method for the determination of trace amounts of nickel is described. At pH 6, nickel reacts with p-acetylarsenazo to form a 1:2 coloured complex with an absorption maximum at 630 nm. The apparent molar absorptivity is 6.5 x 10(4) l.mol(-1) . cm(-1) . Beer's law is obeyed over the concentration range of 0-0.8 microg/ml. The proposed method is selective, sensitive and can be applied to the determination of nickel in aluminum alloy.