Kinetic order with respect to solvent: Acid hydrolysis and preferential solvation of the Reineckate ion

1967 ◽  
Vol 45 (24) ◽  
pp. 3049-3053 ◽  
Author(s):  
Cooper H. Langford ◽  
John F. White
Keyword(s):  
Acid Hydrolysis ◽  
Preferential Solvation ◽  
Solvation Shell ◽  
Resonance Technique ◽  
Kinetic Order ◽  
Solvent Water ◽  
Acetone Water ◽  
Magnetic Resonance Technique ◽  
Hydrolysis Of

The nuclear magnetic resonance technique of preferential solvation analysis developed by Frankel, Stengle, and Langford is applied to determination of the composition of the solvation shell about trans-[Cr(NH3)2(NCS)4]− in acetone–water mixtures. The composition of the solvation shell is correlated with the rate of acid hydrolysis of the chromium complex. It emerges that the solvolysis reaction is second order with respect to the solvolytically reactive solvent, water. The mechanistic implications of the rate law are considered as is the significance of analysis of preferential solvation for the determination of kinetic order of solvolytic reactions.

DETERMINATION OF MICRO-AMOUNTS OF 5β-PREGNAN-3α-OL-20-ONE IN URINE USING INFRARED-SPECTROMETRY

1962 ◽  
Vol 41 (2) ◽  
pp. 234-246 ◽  
Author(s):  
H. J. van der Molen
Keyword(s):  
Infrared Spectrum ◽  
Quantitative Determination ◽  
Acid Hydrolysis ◽  
Chromatographic Separation ◽  
Pure Form ◽  
Infrared Spectrometry ◽  
Hydrolysis Of

ABSTRACT A procedure for the quantitative determination of 5β-pregnan-3α-ol-20-one in urine is described. After acid hydrolysis of the pregnanolone-conjugates in urine, the free steroids are extracted with toluene. Pregnanolone is isolated in a pure form as its acetate; after chromatographic separation of the free steroids on alumina, the fraction containing pregnanolone is acetylated and rechromatographed on alumina. Quantitative determination of the isolated pregnanolone-acetate is carried out with the aid of the infrared spectrum recorded by a micro KBr-wafermethod. The reliability of the method under various conditions is discussed under the headings, specificity, accuracy, precision and sensitivity. It is possible to determine 30–40 μg pregnanolone in a 24-hours urine portion with a precision of 25%.

Determination of Unconjugated and Total N-Acetyl-p-aminophenol (NAPA) in Urine and Serum

1967 ◽  
Vol 13 (3) ◽  
pp. 215-219 ◽  
Author(s):  
Karel P M Heirwegh ◽  
Johan Fevery
Keyword(s):  
Liver Disease ◽  
Acid Hydrolysis ◽  
Azo Dye ◽  
Acidic Medium ◽  
Diazonium Salt ◽  
Accurate Method ◽  
Total N ◽  
Hydrolysis Of ◽  
Urine And Serum

Abstract A sensitive and accurate method is described for the determination of N-acetyl-p-aminophenol (NAPA) and its metabolites in urine and serum. In strongly acidic medium, p-aminophenol (PAP) resulting from differential extraction and acid hydrolysis of total NAPA and unconjugated NAPA, is diazotized and the diazonium salt coupled with N-(1-naphthyl)ethylenediamine (NED) in the presence of ethanol. The blue azo dye formed is determined spectrophotometrically. Application to liver disease is briefly reported.

scholarly journals HPTLC determination of diosgenin in fenugreek seeds

2018 ◽  
Vol 68 (1) ◽  
pp. 97-107 ◽  
Author(s):  
Barbara Król-Kogus ◽  
Khenifi Mohammed Lamine ◽  
Piotr Migas ◽  
Messaoud Boudjeniba ◽  
Mirosława Krauze-Baranowska
Keyword(s):  
Ethyl Acetate ◽  
Acid Hydrolysis ◽  
Methanolic Extract ◽  
Soxhlet Extraction ◽  
African Origin ◽  
Fenugreek Seeds ◽  
Hydrolysis Products ◽  
Hydrolysis Of

Abstract A new HPTLC-densitometric method for diosgenin determination in fenugreek seeds was established after optimization of the conditions for efficient saponin extraction and acid hydrolysis. Several procedures were tested, the best of which was a three-step Soxhlet extraction, followed by hydrolysis of the obtained methanolic extract with 2 mol L-1 H2SO4. Best diosgenin separation from other hydrolysis products was obtained on HPTLC Si60F254 plates u sing a mixture of n-heptane/ethyl acetate (7:3, V/V) and modified anisaldehyde as a spraying reagent. The method was preliminarily validated and the determined amounts of diosgenin in fenugreek seeds of Polish and African origin were found to be similar and ranged from 0.12-0.18 %.

Comparison of the structure of Aβ(1-40) amyloid with the one in complex with polyphenol ε-viniferin glucoside (EVG)

2018 ◽  
Vol 14 (2) ◽  
Author(s):  
Dawid Dułak ◽  
Mateusz Banach ◽  
Zdzisław Wiśniowski ◽  
Leszek Konieczny ◽  
Irena Roterman
Keyword(s):  
Nuclear Magnetic Resonance ◽  
3D Structure ◽  
Soluble Form ◽  
Hydrophobic Core ◽  
Nuclear Magnetic Resonance Technique ◽  
Resonance Technique ◽  
Magnetic Resonance Technique ◽  
Gauss Function ◽  
The One

Abstract The analysis of amyloid structures is much easier recently due to the availability of the solid-state nuclear magnetic resonance technique, which allows the determination of the 3D structure of amyloid forms. The amyloidogenic polypeptide Aβ(1-40) (PDB ID 2M9R, 2M9S) in its soluble form is the object of analysis in this paper. The solubility of this polypeptide is reached due to the presence of a complexed ligand: polyphenol ε-viniferin glucoside. Two forms of complexes available in the PDB were taken for analysis with respect to the presence of a hydrophobic core in the 3D structure of these complexes. The idealized hydrophobic core structure assumed to be accordant with the 3D Gauss function distribution was taken as the pattern. The aim of this analysis is the possible further comparison to the structures of the hydrophobic core present in amyloids. It is shown that the discordant (versus the 3D Gauss function) fragments present in amyloids appear accordant in the discussed complexes.

Determination of 5-methylcytosine by acid hydrolysis of DNA with hydrofluoric acid

1987 ◽  
Vol 167 (2) ◽  
pp. 347-351 ◽  
Author(s):  
J. Catania ◽  
B.C. Keenan ◽  
G.P. Margison ◽  
D.S. Fairweather
Keyword(s):  
Acid Hydrolysis ◽  
Hydrofluoric Acid ◽  
Hydrolysis Of ◽  
Hydrolysis Of Dna
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