scholarly journals The polarimetric determination of sucrose. The effect of clarification with basic lead acetate on the optical activity and copper reducing power of sugar solutions

1908 ◽  
Vol 27 (2) ◽  
pp. 53-58 ◽  
Author(s):  
Francis Watts ◽  
H. A. Tempany
Keyword(s):  
Optical Activity ◽  
Lead Acetate ◽  
Reducing Power

COMPARISON OF VARIOUS METHODS FOR THE CHEMICAL ASSAY OF CORTICOIDS IN URINE

1955 ◽  
Vol 18 (4) ◽  
pp. 374-378
Author(s):  
Mogens Sprechler
Keyword(s):  
Calibration Curve ◽  
Periodic Acid ◽  
Reducing Power ◽  
Standard Technique ◽  
Phosphomolybdic Acid ◽  
Florisil Column ◽  
Chemical Assay ◽  
Chromatographic Procedure ◽  
Acid Reagent

SUMMARY Since 1949 about 10,000 urinary corticoid analyses have been performed routinely in our laboratory. The method used for this purpose was described in 1950 (Sprechler). We determine the corticoids which can be extracted from the urine with chloroform immediately after acidification to pH 1. The extract is washed with sodium hydroxide and water, a Girard separation is performed, and finally the reducing power of the ketonic fraction is measured by means of the phosphomolybdic acid reagent reaction. During the last few years two other chemical reactions have been used for comparison: The formaldehyde and the Porter-Silber method. After a thorough examination of the above methods a standard technique was followed. In the formaldehyde method a microdiffusion in a Conway unit was used instead of distillation of the formaldehyde following the oxidation with periodic acid. The calibration curve was corrected for loss of material by taking the standard doses of DOC through all the procedures of the method. A micromodification of the Porter-Silber method was chosen. Furthermore attempts were made to determine how specific the chromatographic procedure is in the determination of steroids in urinary extracts. For this purpose the Florisil column was used, and the technique described by Nelson & Samuels was followed. Finally we have investigated the glucuronide-bound corticoids in urine in a smaller series of objects.

Accurate measurement of the optical activity of alanine crystals and the determination of their absolute chirality

2017 ◽  
Vol 104 ◽  
pp. 257-266 ◽  
Author(s):  
Kazuhiko Ishikawa ◽  
Yukana Terasawa ◽  
Masahito Tanaka ◽  
Toru Asahi
Keyword(s):  
Optical Activity ◽  
Absolute Chirality

Rapid Thin Layer Chromatographic Method for Determination of Zearalenone and Zearalenol in Grains and Animal Feeds

1984 ◽  
Vol 67 (3) ◽  
pp. 580-582 ◽  
Author(s):  
Steven P Swanson ◽  
Richard A Corley ◽  
Donald G White ◽  
William B Buck
Keyword(s):  
Thin Layer ◽  
Ethyl Acetate ◽  
Salt Solution ◽  
Lead Acetate ◽  
High Performance ◽  
Chromatographic Method ◽  
Inexpensive Method ◽  
Animal Feeds ◽  
Better Than

Abstract A rapid and inexpensive method has been developed for the analysis of zearalenone and zearalenol in grains and animal feeds. The method involves extraction with 75% methanol, precipitation of pigments with lead acetate, and defatting with petroleum ether. The mycotoxins are subsequently partitioned into toluene–ethyl acetate, chromatographed on high performance thin layer chromatographic plates, and detected after treatment with Fast Violet B salt solution. Sensitivity of the method is better than 80 ng/g for zearalenone and 200 ng/g for zearalenol. Ten samples can be completed in less than 2 h. The method is applicable for zearalenone in corn, wheat, barley, millet, and swine feeds.

Quantitative Determination of L-Ascorbic Acid by Gas-Liquid Chromatography

1974 ◽  
Vol 57 (6) ◽  
pp. 1346-1348
Author(s):  
Janis E Schlack
Keyword(s):  
Ascorbic Acid ◽  
Lead Acetate ◽  
Chromatographic Method ◽  
Ethanol Solution ◽  
Lead Salt ◽  
Gas Liquid Chromatography ◽  
Trimethylsilyl Derivative ◽  
Liquid Chromatographic Method ◽  
Liquid Chromatographic

Abstract A gas-liquid chromatographic method for L-ascorbic acid in foods and food products has been devised. Ascorbic acid is extracted into an ethanol solution, precipitated with lead acetate, regenerated from the lead salt as its trimethylsilyl derivative, and chromatographed on an SE- 30 column. Recoveries averaged 100.1%; the standard deviation was ±0.23%.

Determination of absolute configurations from vibrational raman optical activity: Trans-2,3-dimethylthiirane

Talanta ◽  
1993 ◽  
Vol 40 (4) ◽  
pp. 545-549 ◽  
Author(s):  
Prasad L. Polavarapu ◽  
Simeon T. Pickard ◽  
Howard E. Smith ◽  
Thomas M. Black ◽  
Laurence D. Barron ◽  
...  
Keyword(s):  
Optical Activity ◽  
Raman Optical Activity

scholarly journals Determination of the Absolute Stereochemistry of Limonene and α-Santalol by Raman Optical Activity Spectroscopy

2012 ◽  
Vol 7 (4) ◽  
pp. 1934578X1200700 ◽  
Author(s):  
Akira Sakamoto ◽  
Nao Ohya ◽  
Toshio Hasegawa ◽  
Hiroaki Izumi ◽  
Nakako Tokita ◽  
...  
Keyword(s):  
Organic Compounds ◽  
Optical Activity ◽  
Absolute Configuration ◽  
Natural Compounds ◽  
Vibrational Circular Dichroism ◽  
Raman Optical Activity ◽  
The Absolute ◽  
Circular Dichroïsm ◽  
Absolute Stereochemistry

Determining the absolute stereochemistry of organic compounds in solution remains a challenge. We investigated the use of Raman optical activity (ROA) spectroscopy to address this problem. The absolute configurations of (+)-( R)- and (-)-( S)-limonene were determined by ROA spectroscopy, which can be applied to smaller amounts of sample as compared with vibrational circular dichroism (VCD) spectroscopy. This ROA method was also applied to (+)-( E)-α-santalol and shown to be successful in the determination of the absolute configuration of this compound. ROA spectroscopy shows promise as a useful tool for determining the absolute stereochemistry of many natural compounds.

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