摘要:

Previous polarographic and voltammetric studies have led to conflicting statements regarding the reversibility or irreversibility of the 2-electron reduction of pyrazine in the range 3 > pH > 7, with no numerical estimates available describing the rates of electron exchange (k). This paper discusses the current-voltage behavior at the foot of the polarographic wave. Since the DME prevents continuous buildup of surface reductant (C*R), and since solution of the planar diffusion equations suggests that C*R/C*o> 1.0 (n=2) at the foot of the step, it is plausible that the forward reduction term in the Butler-Volmer Equation predominates. Our linear log plots were consistent with this and yieldedk= 3.1 × 10−3cm sec−1andα≃ 1.7, indicating the second step is rate limiting.

ISSN:0003-2719    

DOI:10.1080/00032717908055694

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

The dynamic hydrogen electrode can be used as a versatile reference when smooth platinum is exchanged for platinized platinum, although the H+/H2system is non nernstian with the former kind of electrode.

ISSN:0003-2719    

DOI:10.1080/00032717908055695

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

The reagent ethyl cyanoglyoxalate phenyl-2-carboxyllc acid hydrazone has been developed for the selective amperometric determination of thorium. Commonly associated ions like UO2+2, Pe3+, La3+, Ce4+, and Zr4+do not interfere even when present in ten fold molar excess. 23μg to 4.6mg thorium can be determined within an error of ±1.5 percent.

ISSN:0003-2719    

DOI:10.1080/00032717908055696

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

The extraction was studied of complex of palladium with N-heterocyclic bases (2, 2′-dipyridyl, 1, 10-phenanthroline, 4, 7-dipb. enyl-1, 10-phenanthroline bathophenantroline). Complex compounds are quantitatively extracted by chloroform on the interval of concentrations of hydrogen ions: pH> 6.0 to 1.75 M HCl Dipy; pH> 3.5 to 5.0 M HCl – Phen; pH> 2.5 to 10 M HCl – BPhen. According to UV spectra, the composition of the extracted complex is PdAmCl2(Am=Dipy, Phen, BPhen).

ISSN:0003-2719    

DOI:10.1080/00032717908055697

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

A new chemiluminescence detector for gas chromatography with selectivity for iodinated hydrocarbons is described. Emission from electronically excited iodine monofluoride formed in the reaction of the eluting compounds with the microwave discharge decomposition products of SF6is detected by photon counting. The detector was found to have no significant response to a variety of aliphatic and aromatic compounds containing C, H, O, N, Cl and Br atoms; the only observed interference being a small response to olefinic hydrocarbons. It is expected that the detection limit of one microgram for alkyl iodides can be greatly improved by use of a cooled red-sensitive photomultiplier tube.

ISSN:0003-2719    

DOI:10.1080/00032717908055698

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

The synthetic food dyes separation is described using the paired-ion chromatography. The method used allows the separation of the most permitted food colours and the orange GGN (CI 15980). Differentiation of this dye from its isomer, the sunset yellow (CI 15985), using the usual chromatographic methods still now remains unsuccessful.

ISSN:0003-2719    

DOI:10.1080/00032717908055699

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

Two methods for the determination of available trace metals CCd, Pb, and Cu) in sea water are compared. One method employs anodic stripping voltammetry at controlled pH (8.1, 5.3, and 2); the other method involves sample pretreatment with Chelex-100 resin before ASV analysis. Differences in the results are discussed in terms of the definition of available metal and differences in the analytical methods.

ISSN:0003-2719    

DOI:10.1080/00032717908055700

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

A procedure involving ultraviolet (UV) irradiation followed by gas-liquid chromatographic (GLC) detection of photodecomposition products to confirm the identity of selected organochlorine pesticides is described. The Irradiation intensity was standardized by determining the position relative to the UV source which resulted in equal GLC peak heights for the parent compound and major photo-decomposition product after 8 minutes of exposure of a solution of heptachlor epoxide in isooctane. Chromatograms showing photo-decomposition patterns for 33 compounds are presented. Observations and comments on the applicability of this technique to organo-chlorine pesticide residue confirmation are reported.

ISSN:0003-2719    

DOI:10.1080/00032717908055701

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

The present work deals with the determination of vanadium in high grade carbons by the thermal neutron activation using a Van de Graaff Accelerator. In this study, gadolinium oxide is used as the internal standard material, and the detection limit of this method is c. a. 1 ppm.

ISSN:0003-2719    

DOI:10.1080/00032717908055702

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor

摘要:

A comparison has been made of various procedures for storing trace iodine solutions (10−6M) which were required as calibration standards for a sensitive chemiluminescent assay for iodine. Maximal stability was obtained when the solutions were stored in tightly capped sllanised glass tubes protected from the light.

ISSN:0003-2719    

DOI:10.1080/00032717908055703

出版商:Taylor & Francis Group    

年代:1979

数据来源: Taylor