The hydrolysis of aspirin. A determination of the thermodynamic dissociation constant and a study of the reaction kinetics by ultra-violet spectrophotometry

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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EINE CHEMISCHE METHODE ZUR BESTIMMUNG VON 16-EPI-ÖSTRIOL IM URIN DES MENSCHEN

Acta Endocrinologica ◽

10.1530/acta.0.0440047 ◽

1963 ◽

Vol 44 (1) ◽

pp. 47-66 ◽

Cited By ~ 2

Author(s):

W. Nocke ◽

H. Breuer

Keyword(s):

Melting Point ◽

Phosphoric Acid ◽

Aqueous Alkali ◽

Percentage Error ◽

Organic Layer ◽

Maximum Percentage ◽

Chemical Determination ◽

Routine Assay ◽

Hydrolysis Of

ABSTRACT A method for the chemical determination of 16-epi-oestriol in the urine of nonpregnant women with a qualitative sensitivity of less than 0.5 μg/24 h is described. The separation of 16-epi-oestriol and oestriol is accomplished by converting 16-epi-oestriol into its acetonide, a reaction which is stereoselective for cis-glycols and therefore not undergone by oestriol as a trans-glycol. Following partition between chloroform and aqueous alkali, the acetonide of 16-epi-oestriol is completely separated with the organic layer whereas oestriol as a strong phenol remains in the alkaline phase. 16-epi-oestriol is chromatographed on alumina as the acetonide and determined as a Kober chromogen. This procedure can easily be incorporated into the method of Brown et al. (1957 b) thus making possible the simultaneous routine assay of oestradiol-17β, oestrone, oestriol and 16-epi-oestriol from one sample of urine. The specificity of the method was established by separation of 16-epi-oestriol from nonpregnancy urine as the acetonide, hydrolysis of the acetonide by phosphoric acid, isolation of the free compound by microsublimation and identification by micro melting point, colour reactions and chromatography. The accuracy of the method is given by a mean recovery of 64% for pure crystalline 16-epi-oestriol when added to hydrolysed urine in 5–10 μg amounts. The precision is given by s = 0.24 μg/24 h. For the duplicate determination of 16-epi-oestriol the qualitative sensitivity is 0.44 μg/24 h, the maximum percentage error being ± 100% The quantitative sensitivity (±25% error) is 1.7 μg/24 h.

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INDIREKTE PAPIERCHROMATOGRAPHISCHE METHODE ZUR BESTIMMUNG DER HARNOESTROGENE

Acta Endocrinologica ◽

10.1530/acta.0.0380545 ◽

1961 ◽

Vol 38 (4) ◽

pp. 545-562 ◽

Cited By ~ 2

Author(s):

L. Kecskés ◽

F. Mutschler ◽

I. Glós ◽

E. Thán ◽

I. Farkas ◽

...

Keyword(s):

Pregnant Women ◽

Granulosa Cell ◽

Iron Content ◽

List Type ◽

Granulosa Cell Tumour ◽

Hydrolysis Of ◽

Phenol Fraction ◽

Qualitative Determination

ABSTRACT 1. An indirect paperchromatographic method is described for separating urinary oestrogens; this consists of the following steps: acidic hydrolysis, extraction with ether, dissociation of phenol-fractions with partition between the solvents. Previous purification of phenol fraction with the aid of paperchromatography. The elution of oestrogen containing fractions is followed by acetylation. Oestrogen acetate is isolated by re-chromatography. The chromatogram was developed after hydrolysis of the oestrogens 'in situ' on the paper. The quantity of oestrogens was determined indirectly, by means of an iron-reaction, after the elution of the iron content of the oestrogen spot, which was developed by the Jellinek-reaction. 2. The method described above is satisfactory for determining urinary oestrogen, 17β-oestradiol and oestriol, but could include 16-epioestriol and other oestrogenic metabolites. 3. The sensitivity of the method is 1.3–1.6 μg/24 hours. 4. The quantitative and qualitative determination of urinary oestrogens with the above mentioned method was performed in 50 pregnant and 9 non pregnant women, and also in 2 patients with granulosa cell tumour.

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Determination of δ-hexadecansultone in sodium α-olefinesulphonates and liquid detergents using gas chromatography-mass spectrometry (GC/MS)

Industrial laboratory Diagnostics of materials ◽

10.26896/1028-6861-2019-85-7-16-21 ◽

2019 ◽

Vol 85 (7) ◽

pp. 16-21

Author(s):

Liliya R. Mubarakova ◽

German K. Budnikov

Keyword(s):

Multicomponent Mixture ◽

Operating Mode ◽

Complete Separation ◽

Gas Chromatography Mass Spectrometry ◽

Liquid Detergent ◽

Cyclic Esters ◽

Alcohol Water ◽

Household Chemicals ◽

Hydrolysis Of

Sultones are cyclic esters of hydroxysulfonic acids, which are formed in the process of sulfonation of α-olefins with sulfur trioxide gas. More stable sultones may be present in the final product — an anionic surfactant — sodium α-olefin sulfonate (AOC-Na). AOC-Na is widely used in the production of household chemicals and cosmetic products, including liquid dishwashing detergents. Sultones are strong skin sensitizers, their level in AOC-Na should be strictly controlled and not exceed 5 ppm. Operational and strict control of the sultone content upon AOC-Na production allows timely adjustment at the stage of hydrolysis, which leads to a more complete disclosure of the sultone cycle with the formation of the corresponding olefin sulfonates and hydroxyalkanesulfonates. We propose a method for determining δ-hexadecansultone in liquid dishwashing detergents and sodium α-olefinsulfonates obtained on the basis of α-olefins of C14 – C16 fractions using GC/MS, which provides shortening of sample preparation and keeps the sensitivity with a detection limit of 0.02 mg/kg. The effect of various weakly polar and non-polar organic solvents used for Sultone extraction from AOC-Na and liquid detergent on liquid extraction based on the dispersion of the extractant in an alcohol/water phase is studied. When selecting the solvent we have shown that the use of diethyl ether provided the best extraction of the analyte. Determination of the analyte extraction recovery was performed using the reaction of hydrolysis of the extracted mixture. We specified the operating mode of the device which provided complete separation of the components of the analyzed compounds including the samples of liquid detergent for dishes being a multicomponent mixture of complex composition.

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Rubber and plastics hoses. Determination of ultra-violet resistance under static conditions

10.3403/00580307 ◽

1989 ◽

Keyword(s):

Ultra Violet ◽

Static Conditions

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Polarographic study of hydrolysis of [8-lysine]vasopressin and its derivatives with blood serum of pregnant women

Collection of Czechoslovak Chemical Communications ◽

10.1135/cccc19801099 ◽

1980 ◽

Vol 45 (4) ◽

pp. 1099-1108 ◽

Cited By ~ 1

Author(s):

Mikuláš Chavko ◽

Michal Bartík ◽

Evžen Kasafírek

Keyword(s):

Blood Serum ◽

Pregnant Women ◽

Degree Of Hydrolysis ◽

Polarographic Study ◽

Ph Optimum ◽

Lysine Vasopressin ◽

Rate Of Hydrolysis ◽

Hydrolysis Of ◽

Vasopressin Analogues

A polarographic study of the hydrolysis of [8-lysine]vasopressin and some hormonogens of the vasopressin series with the blood serum of women in the last week of pregnancy was studied. The dependence of hydrolysis on pH (pH optimum: 7.4-7.50, substrate concentration (Km 1.2 . 10-5M), pH stability and thermal stability were determined. The rate of hydrolysis of individual vasopressin analogues decreases in the order: [8-lysine]vasopressin > Nα-glycyl-prolyl[8-lysine]-vasopressin > Nα-leucyl-[8-lysine]vasopressin > Nα-alanyl-[8-lysine]vasopressin > Nα-phenyl alanyl-[8-lysine]vasopressin > Nα-diglycyl-[8-lysine]vasopressin > Nα-prolyl-[8-lysine]vasopressin > Nα-triglycyl-[8-lysine]vasopressin > Nα-sarcosyl-glycyl-[8-lysine]vasopressin. The degree of hydrolysis gradually increases to a multiple with the length of the pregnancy in consequence of the presence of oxytocine. However, vasopressin is also hydrolysed to a small extent with the enzymes from the blood sera of non-pregnant women. Under similar analytical conditions oxytocin was not hydrolysed with the sera of non-pregnant women and therefore oxytocin is a more suitable substrate than vasopressin for polarographic determination of serum oxytocinase.

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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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Enzymatic colorimetry of lecithin and sphingomyelin in aqueous solution.

Clinical Chemistry ◽

10.1093/clinchem/29.8.1513 ◽

1983 ◽

Vol 29 (8) ◽

pp. 1513-1517 ◽

Cited By ~ 10

Author(s):

M W McGowan ◽

J D Artiss ◽

B Zak

Keyword(s):

Aqueous Solution ◽

Hydrogen Peroxide ◽

Amniotic Fluid ◽

Enzymatic Reaction ◽

Detergent Solution ◽

Enzymatic Determination ◽

Red Color ◽

Hydrolysis Of ◽

Zwitterionic Detergent

Abstract A procedure for the enzymatic determination of lecithin and sphingomyelin in aqueous solution is described. The phospholipids are first dissolved in chloroform:methanol (2:1 by vol), the solvent is evaporated, and the residue is redissolved in an aqueous zwitterionic detergent solution. The enzymatic reaction sequences of both assays involve hydrolysis of the phospholipids to produce choline, which is then oxidized to betaine, thus generating hydrogen peroxide. The hydrogen peroxide is subsequently utilized in the enzymatic coupling of 4-aminoantipyrine and sodium 2-hydroxy-3,5-dichlorobenzenesulfonate, an intensely red color being formed. The presence of a non-reacting phospholipid enhances the hydrolysis of the reacting phospholipid. Thus we added lecithin to the sphingomyelin standards and sphingomyelin to the lecithin standards. This precise procedure may be applicable to determination of lecithin and sphingomyelin in amniotic fluid.

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