Efficiency of decomposition procedures for the determination of some elements in soils by atomic spectroscopic methods

1998 ◽  
Vol 360 (2) ◽  
pp. 219-224 ◽  
Author(s):  
J. Medved' ◽  
Vladim�r Stre?ko ◽  
Jana Kubov� ◽  
Jozefa Polakovi?ov�
Keyword(s):  
Spectroscopic Methods

The protonation of the ethylenediphosphinetetraacetate anion and the crystal structure of the bis (hydrogen bromide) of ethylenediphosphinetetraacetic acid

1981 ◽  
Vol 46 (12) ◽  
pp. 3063-3073 ◽  
Author(s):  
Jana Podlahová ◽  
Bohumil Kratochvíl ◽  
Vratislav Langer ◽  
Josef Šilha ◽  
Jaroslav Podlaha
Keyword(s):  
Crystal Structure ◽  
Hydrogen Bonds ◽  
Structure Determination ◽  
Free Acid ◽  
Hydrogen Bromide ◽  
Carboxyl Groups ◽  
Spectroscopic Methods ◽  
X Ray ◽  
Partial Formation

The equilibria and mechanism of addition of protons to the ethylenediphosphinetetraacetate anion (L4-) were studied in solution by the UV, IR, 1H and 31P NMR spectroscopic methods. A total of six protons can be bonded to the anion. They are added stepwise, first with partial formation of zwitterions containing P-H bonds, which then dissociate with formation of the free acid, H4L, where all four protons are bonded in carboxyl groups. The formation of zwitterions is strongly dependent on the concentration. In the final stage, the acid bonds two additional protons to form the bis-phosphonium cation, H6L2+. A number of isostructural salts containing this cation, H4L.2 HX (X = Cl, Br, I), have been prepared. The X-ray crystal structure determination of the bromide confirmed the expected arrangement. The bromide crystals are monoclinic, a = 578.2, b = 1 425.0, c = 1 046.7 pm, β = 103.07° with a space group of P21/c, Z = 2. The final R factor was 0.059 based on 1 109 observed reflections. The structure consists of H6L2+ cations containing protons bonded to phosphorus atoms (P-H distance 134 pm) and of bromide anions, located in gaps which are also sufficiently large for I- anions in the isostructural iodide. The interbonding of phosphonium cations proceeds through hydrogen bonds, C-OH...O=C, in which the O...O distance is 275.3 pm.

scholarly journals Electrochemical design of a new nanosensor based on cobalt nanoparticles, chitosan and MWCNT for the determination of daclatasvir: a hepatitis C antiviral drug

RSC Advances ◽  
2017 ◽  
Vol 7 (2) ◽  
pp. 1118-1126 ◽  
Author(s):  
Shereen M. Azab ◽  
Amany M. Fekry
Keyword(s):  
Hepatitis C ◽  
Health System ◽  
Antiviral Drug ◽  
Cobalt Nanoparticles ◽  
Essential Medicines ◽  
World Health ◽  
Spectroscopic Methods ◽  
Basic Health ◽  
The World

Daclatasvir (DAC) is listed on the World Health Organization's list of essential medicines needed in a basic health system, therefore, electrochemical and impedance spectroscopic methods are necessary.

The Power of Spectroscopic Methods in the Determination of the Relative Orientation of Guest Molecules in a Stretched Polyethylene (PE) Matrix

1985 ◽  
Vol 39 (6) ◽  
pp. 976-979 ◽  
Author(s):  
Joanna Konwerska-Hrabowska
Keyword(s):  
Interaction Energy ◽  
Relative Orientation ◽  
Spectroscopic Methods ◽  
Guest Molecules ◽  
Spectroscopic Measurements ◽  
Host Molecules

Comparison of values for the relative orientation of pyrene guest molecules and PE host macromolecules obtained by spectroscopic measurements and by calculations of the minimum of the interaction energy between the guest and host molecules is presented. Accordance between both results as well as with the Groszek model is found.

scholarly journals SPECTROSCOPIC METHODS TO DETERMINATION OF GEOTHITE IN KAOLINITE

2020 ◽  
Vol 17 (35) ◽  
pp. 303-314
Author(s):  
Marcelo Kehl; ; ; ; DE SOUZA ◽  
Marcos Antônio KLUNK ◽  
Soyane Juceli Siqueira XAVIER ◽  
Mohuli DAS ◽  
Sudipta DASGUPTA
Keyword(s):  
Spectroscopic Methods ◽  
Industrial Minerals ◽  
X Ray Diffraction ◽  
Simple Shape ◽  
X Ray ◽  
Spectroscopic Monitoring ◽  
Partial Release ◽  
Primary Minerals

One of the main contaminants of kaolinite, the iron, directly impacts quality in its commercial value. The spectroscopic monitoring, measured the depth of absorption of kaolinite, is compared with the literature in order to identify possible contaminants. The occurrence of kaolinite is due to the formation of primary minerals after the partial release of cations and silicon. This clay-mineral has a simple shape, with variable crystallographic imperfections, especially in the presence of iron, which replaces aluminum in the mineral chain, causing various structural disorganizations. The extraction of industrial minerals combined with geological studies, allows the development of new sources of energy, such as clay minerals, in particular kaolinite. Depending on the origin of the kaolinites, the presence of iron oxides in its structure, Fe2O3 and FeO(OH), are common. By comparing the results of spectroscopy (X-ray fluorescence, X-ray diffraction, RAMAN) and imaging using SEM-EDS, it was possible to identify kaolinite, with a higher determination coefficient, when the proportion of kaolinite reaches 60% or more in the mix. Kaolinite can be identified and quantified with a high correlation in the mixture from the sample absorption. Thus, the method has great potential to assist in quantifying and, consequently, in discriminating the quality of kaolinite.

scholarly journals Comparison of two modern infrared spectroscopic methods for the determination of orientation in drawn bulk polymers

2000 ◽  
Vol 19 (2) ◽  
pp. 205-212 ◽  
Author(s):  
Pavel Schmidt ◽  
Miroslav Raab ◽  
Jan Kolařı́k ◽  
Klaus J Eichhorn
Keyword(s):  
Spectroscopic Methods ◽  
Infrared Spectroscopic ◽  
Bulk Polymers

TLC Determination of Aquatic Humic Acids

1992 ◽  
Vol 26 (9-11) ◽  
pp. 2567-2570 ◽  
Author(s):  
M. Kaštelan-Macan ◽  
Š. Cerjan-Stefanovic ◽  
D. Jalšovec
Keyword(s):  
Thin Layer ◽  
Quantitative Determination ◽  
Humic Acids ◽  
Visible Spectrum ◽  
Solvent System ◽  
Spectroscopic Methods ◽  
Precise Method ◽  
Adsorption Resin ◽  
Layer Chromatography

Humic acids are mostly determined by spectroscopic methods, although they are not accurate enough, because humic acids possess no maximum absorption at any wavelength in the ultraviolet and visible spectrum. In this contribution the accurate and precise method for aquatic humic acids determination, using thin layer chromatography, was worked out. Previously, humic acids were separated and preconcentrated -from the river water, using macroreticular adsorption resin Amberlite XAD-4, and subsequently determined by TLC. The Chromatographie system was: silicagel HF254(Merck, precoated plates 20 × 20 cm) and NH3 -acetone (60:40,v/v) as a solvent system. Quantitative determination was made by Camag– Turner 111 Fluorimeter, by measuring UV–quenching.

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