Kinetic study of the acid hydrolysis of sucrose and lactose and kinetic determination of sucrose using a periodate-selective electrode

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%.

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Benzyl ethers of methyl α-D-glucopyranoside

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19801959 ◽

1980 ◽

Vol 45 (7) ◽

pp. 1959-1963 ◽

Cited By ~ 1

Author(s):

Dušan Joniak ◽

Božena Košíková ◽

Ludmila Kosáková

Keyword(s):

Kinetic Study ◽

Spectrophotometric Determination ◽

Reductive Cleavage ◽

Ether Bond ◽

Benzyl Ethers ◽

Acid Catalyzed ◽

Model Substances ◽

Hydrolysis Of

Methyl 4-O-(3-methoxy-4-hydroxybenzyl) and methyl 4-O-(3,5-dimethoxy-4-hydroxybenzyl)-α-D-glucopyranoside and their 6-O-isomers were prepared as model substances for the ether lignin-saccharide bond by reductive cleavage of corresponding 4,6-O-benzylidene derivatives. Kinetic study of acid-catalyzed hydrolysis of the compounds prepared was carried out by spectrophotometric determination of the benzyl alcoholic groups set free, after their reaction with quinonemonochloroimide, and it showed the low stability of the p-hydroxybenzyl ether bond.

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A kinetic study of the acid autoxidation of tryptophan

Australian Journal of Chemistry ◽

10.1071/ch9722139 ◽

1972 ◽

Vol 25 (10) ◽

pp. 2139 ◽

Cited By ~ 8

Author(s):

M Stewart ◽

CH Nicholls

Keyword(s):

Free Radical ◽

Amino Acid ◽

Kinetic Study ◽

Acid Hydrolysis ◽

Soda Glass ◽

Glass Containers ◽

Hydrolysis Of

The decomposition of tryptophan in aqueous HC1 at 100�C has been shown to proceed by a free-radical autoxidation mechanism. The acid functions by protonating the amino acid at either the 1- or 3-positions prior to autoxidation and so 1-methyltryptophan is also decomposed under these conditions. Impurities present in the soda glass containers used are shown to be responsible for the initiation of the reaction. The decomposition of tryptophan during the acid hydrolysis of proteins is considered in the light of these results.

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

Clinical Chemistry ◽

10.1093/clinchem/13.3.215 ◽

1967 ◽

Vol 13 (3) ◽

pp. 215-219 ◽

Cited By ~ 4

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.

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HPTLC determination of diosgenin in fenugreek seeds

Acta Pharmaceutica ◽

10.2478/acph-2018-0002 ◽

2018 ◽

Vol 68 (1) ◽

pp. 97-107 ◽

Cited By ~ 2

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 %.

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