Solubility Determination of Cholesterol Polymorphs in Organic Solvents

1966 ◽  
Vol 12 (4) ◽  
pp. 206-210 ◽  
Author(s):  
Royce D Stauffer ◽  
Fritz Bischoff
Keyword(s):  
Olive Oil ◽  
Organic Solvents ◽  
Aqueous Phase ◽  
Higher Alcohols ◽  
Solubility Determination ◽  
Crystalline Forms

Abstract In a study of the solubility of crystalline forms of cholesterol in various solvents, the solubilities (per cent by weight) of cholesterol needles and hydrated plates at 38° were, respectively, 4.0 and 3.2% in olive oil; 2.6 and 1.9% in tetradecane; 26.2 and 9% in toluene; and 21.0 and 7% in cyclohexane. When these solvents are in equilibrium with an aqueous phase, needles are converted to plates. Pseudomorph ( dehydrated) plates in olive oil have the solubility of needles. These differences may have significance in studies involving cholesterol pathogenesis. The modified Zak reaction with ethanol could not be used for the assay of cholesterol in olive oil since the reaction product was turbid. Higher alcohols were studied as a substitute for ethanol; 2-propanol was satisfactory.

A simple method for the determination of 5-vinyloxazolidine-2-thione in rapeseed meal

1969 ◽  
Vol 47 (8) ◽  
pp. 817-818 ◽  
Author(s):  
A. Szewczuk ◽  
P. Mastalerz ◽  
W. Nadwyczawski
Keyword(s):  
Organic Solvents ◽  
Aqueous Phase ◽  
Rapeseed Meal ◽  
New Method ◽  
Simple Method ◽  
Titrimetric Method ◽  
Azide Ion ◽  
The Family ◽  
Titrimetric Determination

5-Vinyloxazolidine-2-thione (VOT), a goitrogenic substance occurring in plants of the family Cruciferae, was found to catalyze the reduction of iodine by azide ion, the consumption of iodine being proportional to the amount of VOT. Based on these observations, a sensitive, titrimetric method of VOT determination was developed. The new method obviates the necessity of VOT extraction from the aqueous phase with organic solvents. Sensitivity and accuracy of titrimetric determination of VOT are comparable with those of spectrophotometric procedures.

UNTERSUCHUNGEN ÜBER DIE EXTRAKTION DES ROTEN KOBER-FARBSTOFFS DURCH ORGANISCHE LÖSUNGSMITTEL ZUR ÖSTROGENBESTIMMUNG IM HARN

1960 ◽  
Vol XXXV (I) ◽  
pp. 34-48 ◽  
Author(s):  
Gerd Ittrich
Keyword(s):  
Menstrual Cycle ◽  
Organic Solvents ◽  
Urine Sample ◽  
Phenol Derivatives ◽  
Organische Lösungsmittel ◽  
Colour Complex

ABSTRACT A series of organic solvents and phenol derivatives have been examined for the extraction of the pink Kober-colour complex. Optimal results could be achieved for fluorimetry by a solution of 2 % (w/v) p-nitrophenol and 1 % (v/v) ethanol in acetylenetetrabromide, when the green mercury line (546 mμ was used as primary light. The sensitivity, stability and specificity have been improved, compared with the previously described reaction. By changing the sequence of purification steps and by reducing the volume of the urine sample (5 ml) the method for the determination of total oestrogens has been simplified. Approximately 10 determinations can be done within 3–4 hours by one person. Recovery experiments and comparative determinations with a previously described method have been carried out. The excretion of total oestrogens in a complete menstrual cycle is determined with the described method.

Generic method for determination of volatile organic solvents in cosmetics

2014 ◽  
Vol 32 (11) ◽  
pp. 1251
Author(s):  
Jing DA ◽  
Xianglu HUANG ◽  
Gangli WANG ◽  
Jin CAO ◽  
Qingsheng ZHANG
Keyword(s):  
Organic Solvents ◽  
Volatile Organic

Determination of Dimetridazole and Ipronidazole in Feeds at Cross-Contamination Levels

1988 ◽  
Vol 71 (3) ◽  
pp. 474-477 ◽  
Author(s):  
Duane D Hughes
Keyword(s):  
Thin Layer ◽  
Rapid Method ◽  
Aqueous Phase ◽  
Borate Buffer ◽  
Cross Contamination ◽  
Chromatographic System ◽  
Arsanilic Acid ◽  
Contamination Levels ◽  
Benzene Extract

Abstract A rapid method for the determination of dimetridazole and ipronidazole in feeds is described. The compounds are extracted from a borate buffer (pH 8.65) with benzene, partitioned into IN HC1, and then partitioned back into benzene from a basic aqueous phase. The benzene extract is concentrated and injected onto a nonpolar (Apiezon L) gas chromatographic column for determination by 63Ni electroncapture detection. Recoveries from feeds of various composition, spiked at 0.2 ppm with both dimetridazole and ipronidazole, ranged from 70 to 115%; for the same feeds spiked at 1 ppm or more, the recoveries were greater than 80%. Carbadox, furazolidone, levamisole, oxytetracycline, chlortetracycline, sulfamethazine, sulfaquinoxaline, arsanilic acid, piperazine, penicillin, and commonly added vitamins and minerals do not interfere. A 2-dimensional thin layer chromatographic system is presented as a means of additional identification.

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