摘要:

Emission spectra of water samples stored in polyethylene botles show the pressence of impurities whose concentration roughly parallels the length of storage. With excitation at 280 nm, water stored for 3 months in polyethylene gave a blank signal equivalent to the emission of 10−7Mbovine serum albumin. Caution should be exercised in using plastic bottles for fluorometric reagents.

ISSN:0003-2719    

DOI:10.1080/00032717208064346

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

The possibility of formation of mixed complex compound niobium(V)-pyrocatechol (PC)-thenoyltrifluoracetone (TTA) has been shown. Optimum conditions for the formation of such a compound have been found (7.5MHCI, 0.3MTTA, 0.4MPC) and the molar ratio Nb (V):PC:TTA=1:2:2 has been established by the equilibrium shift method. The absorption spectrum of the chloroform extract of the Nb-PC-TTA compound has a maximum at 414 nm, ϵ= (7.7±0.2) × 103. The influence of other ions on extraction-photometric determination of niobium (V) with PC and TTA is discussed.

ISSN:0003-2719    

DOI:10.1080/00032717208064347

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

The characteristic p.m.r. signal at τ 8.4–8.6 given by the CH3-C group of a pyruvic acid ketal (1-carboxyethylidene derivative)may be used to demonstrate the presence of such a substituent in polysaccharides. Similar signals are given when the pyruvic acid ketal is methylated or reduced. The method is convenient for monitoring purification procedures and chemical transformations of polysaccharides such as are involved in structural studies. In certain cases the molar ratio of pyruvic acid may be estimated.

ISSN:0003-2719    

DOI:10.1080/00032717208064348

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

A rapid method for the determination of alky1 mercury compounds in fish tissue is presented. The method is based on gasliquid chromatographic separation, combustion of the column effluent in a furnace and measurement of the resulting atomic vapor by atomic absorption spectrophotometry.

ISSN:0003-2719    

DOI:10.1080/00032717208064349

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

Phenylfuorone is widely used as an analytical reagent for the determination of a number of elements. Commercially available phenylfluorone has been spectroscopically examined, and the main impurity interfering with the reagent has been found.

ISSN:0003-2719    

DOI:10.1080/00032717208064350

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

Evidence for the formation of Fe(III) and Fe(II) complexes with pyruvate ion is presented. Complexes with a 1:2 ratio of Fe(II) to pyruvate and 1:1 ratio of Fe(III) to pyruvate were identified by spectrophotometry. The complexation results in partial kinetic control of the electrochemical oxidation of Fe(II) in citrate buffer. In addition, Fe(III) was found to be chemically reduced by pyruvate. The apparent first order rate constant at 25[ddot]C is 7.12 × 10−2s−1in pH 4.0 pyruvate buffer and 1.24 × 10−1s−1in pH 3.2 pyruvate buffer. In pH 4.0 citrate buffer the reaction is not first order and is significantly slower.

ISSN:0003-2719    

DOI:10.1080/00032717208064351

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

The sensitivity for selenium determination with atomic absorption spectrophotometry is enhanced to a large extent by introducing hydrogen selenide gas into an argon-hydrogen flame. As a reducing agent, zinc granular and stannous chloride is successfully used for quantitative and rapid productions of hydrogen selenide from selenium(IV) solution. The sensitivity for 1 % absorption of the signal is estimated to be about 0.02 ppm of selenium.

ISSN:0003-2719    

DOI:10.1080/00032717208064352

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

A new method for the end-point detection in complexometric titration using a tensammetric wave of organic reagents such as oxine and alizarin complexone (ALC) was studied. The tensammetric wave of these reagents disappears by their chelate formation and reappears by the liberation of free indicator during the exchange reaction between indicator chelate and EDTA. This mechanism is utilized for the end-point detection in complexometric titration of metals. Since the sensitivity of tensammetric wave is extremely high, very sharp end-point can be obtained for the titration of metals even in the concentration of 10−5M.

ISSN:0003-2719    

DOI:10.1080/00032717208064353

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

A novel “electrochemical ionic distribution coefficient”, i is defined based on Guggenheim's electrochemical potential concept. i correlates the activities of a given ion in different solvents. The definition of i is entirely consistent with the practice to interrelate chemical equilibrium constants in various solvents via the classical ionic distribution coefficient i.

ISSN:0003-2719    

DOI:10.1080/00032717208064354

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor

摘要:

A procedure which combines electrochemical deposition and ESCA measurements for the determination of trace levels of metals in solution is described. The method is demonstrated by an experiment in which microgram quantities of Pb, Cd, and Bi are deposited on a mercury-coated platinum electrode and then detected by ESCA measurements.

ISSN:0003-2719    

DOI:10.1080/00032717208064355

出版商:Taylor & Francis Group    

年代:1972

数据来源: Taylor